Regulation of Gene Expression Lecture Outline Overview: Differential Expression of Genes • Both prokaryotes and eukaryotes alter their patterns of gene expression in response to changes in environmental conditions. • Multicellular eukaryotes also develop and maintain multiple cell types. ○ Each cell type contains the same genome but expresses a different subset of genes. ○ During development, gene expression must be carefully regulated to ensure that the right genes are expressed only at the correct time and in the correct place. • Gene expression in eukaryotes and bacteria is often regulated at the transcription stage. ○ Control of other levels of gene expression is also important. • RNA molecules play many roles in regulating eukaryotic gene expressions. • Disruptions in gene regulation may lead to cancer. Concept 18.1 Bacteria often respond to environmental change by regulating transcription • Natural selection favors bacteria that express only those genes whose products are needed by the cell. ○ A bacterium in a tryptophan-rich environment that stops producing tryptophan conserves its resources. • Metabolic control occurs on two levels. • First, cells can adjust the activity of enzymes already present. ○ This may happen by feedback inhibition, in which the activity of the first enzyme in a pathway is inhibited by the pathway’s end product. ○ Feedback inhibition, typical of anabolic (biosynthetic) pathways, allows a cell to adapt to short-term fluctuations in the supply of a needed substance. • Second, cells can vary the number of specific enzyme molecules they make by regulating gene expression. ○ The control of enzyme production occurs at the level of transcription, the synthesis of messenger RNA coding for these enzymes. ○ Genes of the bacterial genome may be switched on or off by changes in the metabolic status of the cell. • The basic mechanism for the control of gene expression in bacteria, known as the operon model, was described by Francois Jacob and Jacques Monod in 1961. The operon model controls tryptophan synthesis. • Escherichia coli synthesizes tryptophan from a precursor molecule in a series of steps, with each reaction catalyzed by a specific enzyme. • The five genes coding for the subunits of these enzymes are clustered together on the bacterial chromosome as a transcription unit, served by a single promoter. • Transcription gives rise to one long mRNA molecule that codes for all five polypeptides in the tryptophan pathway. • The mRNA is punctuated with start and stop codons that signal where the coding sequence for each polypeptide begins and ends. • A key advantage of grouping genes with related functions into one transcription unit is that a single on-off switch can control a cluster of functionally related genes. ○ In other words, these genes are coordinately controlled. • When an E. coli cell must make tryptophan for itself, all the enzymes are synthesized at one time. • The switch is a segment of DNA called an operator. • The operator, located within the promoter or between the promoter and the enzyme-coding genes, controls the access of RNA polymerase to the genes. • The operator, the promoter, and the genes they control constitute an operon. ○ The trp operon (trp for tryptophan) is one of many operons in the E. coli genome. • By itself, an operon is turned on: RNA polymerase can bind to the promoter and transcribe the genes of the operon. • The operon can be switched off by a protein called the trp repressor. ○ The repressor binds to the operator, blocks attachment of RNA polymerase to the promoter, and prevents transcription of the operon’s genes. • Each repressor protein recognizes and binds only to the operator of a particular operon. • The trp repressor is the protein product of a regulatory gene called trpR, which is located at some distance from the operon it controls and has its own promoter. • Regulatory genes are transcribed continuously at slow rates, and a few trp repressor molecules are always present in an E. coli cell. • Why is the trp operon not switched off permanently? • First, binding by the repressor to the operator is reversible. ○ An operator vacillates between two states, with and without a repressor bound to it. ○ The relative duration of each state depends on the number of active repressor molecules around. • Second, repressors contain allosteric sites that change shape depending on the binding of other molecules. ○ The trp repressor has two shapes: active and inactive. ○ The trp repressor is synthesized in an inactive form with little affinity for the trp operator. ○ Only if tryptophan binds to the trp repressor at an allosteric site does the repressor protein change to the active form that can attach to the operator, turning the operon off. • Tryptophan functions in the trp operon as a corepressor, a small molecule that cooperates with a repressor protein to switch an operon off. • When concentrations of tryptophan in the cell are high, more tryptophan molecules bind with trp repressor molecules, activating them. ○ The active repressors bind to the trp operator and turn the operon off. • At low levels of tryptophan, most of the repressors are inactive, and transcription of the operon’s genes resumes. There are two types of operons: repressible and inducible. • The trp operon is an example of a repressible operon, one that is inhibited when a specific small molecule (tryptophan) binds allosterically to a regulatory protein. • In contrast, an inducible operon is stimulated (induced) when a specific small molecule interacts with a regulatory protein. • The classic example of an inducible operon is the lac operon (lac for lactose). • Lactose (milk sugar) is available to E. coli in the human colon if the host drinks milk. ○ Lactose metabolism begins with hydrolysis of lactose into its component monosaccharides, glucose and galactose. ○ This reaction is catalyzed by the enzyme ß-galactosidase. • Only a few molecules of b-galactosidase are present in an E. coli cell grown in the absence of lactose. ○ If lactose is added to the bacterium’s environment, the number of ß-galactosidase molecules increases by a thousandfold within 15 minutes. • The gene for ß-galactosidase is part of the lac operon, which includes two other genes coding for enzymes that function in lactose metabolism. • The regulatory gene, lacI, located outside the operon, codes for an allosteric repressor protein that can switch off the lac operon by binding to the operator. • Unlike the trp operon, the lac repressor is active all by itself, binding to the operator and switching the lac operon off. ○ An inducer inactivates the repressor. ○ When lactose is present in the cell, allolactose, an isomer of lactose, binds to the repressor. ○ This inactivates the repressor, and the lac operon can be transcribed. • Repressible enzymes generally function in anabolic pathways, synthesizing end products from raw materials. ○ When the end product is present in sufficient quantities, the cell can allocate its resources to other uses. • Inducible enzymes usually function in catabolic pathways, digesting nutrients to simpler molecules. ○ By producing the appropriate enzymes only when the nutrient is available, the cell avoids making proteins that are not needed. • Both repressible and inducible operons demonstrate negative control of genes because active repressors switch off the active form of the repressor protein. ○ It may be easier to see this for the trp operon, but it is also true for the lac operon. ○ Allolactose induces enzyme synthesis not by acting directly on the genome, but by freeing the lac operon from the negative effect of the repressor. Some gene regulation is positive. • Positive gene control occurs when a protein molecule interacts directly with the genome to switch transcription on. • The lac operon is an example of positive gene regulation. • When glucose and lactose are both present, E. coli preferentially uses glucose. ○ The enzymes for glucose breakdown in glycolysis are always present in the cell. • Only when lactose is present and glucose is in short supply does E. coli use lactose as an energy source and synthesize the enzymes for lactose breakdown. • When glucose levels are low, cyclic AMP (cAMP) accumulates in the cell. • The regulatory protein catabolite activator protein (CAP) is an activator of transcription. • When cAMP is abundant, it binds to CAP, and the regulatory protein assumes its active shape and can bind to a specific site at the upstream end of the lac promoter. ○ The attachment of CAP to the promoter increases the affinity of RNA polymerase for the promoter, directly increasing the rate of transcription. ○ Thus, this mechanism qualifies as positive regulation. • If glucose levels in the cell rise, cAMP levels fall. ○ Without cAMP, CAP detaches from the operon and lac operon is transcribed only at a low level. • The lac operon is under dual control: negative control by the lac repressor and positive control by CAP. ○ The state of the lac repressor (with or without bound allolactose) determines whether or not the lac operon’s genes are transcribed. ○ The state of CAP (with or without bound cAMP) controls the rate of transcription if the operon is repressor-free. ○ The operon has both an on-off switch and a volume control. • CAP works on several operons that encode enzymes used in catabolic pathways. It affects the expression of more than 100 E. coli genes. ○ If glucose is present and CAP is inactive, then the synthesis of enzymes that catabolize other compounds is slowed. ○ If glucose levels are low and CAP is active, then the genes that produce enzymes that catabolize whichever other fuel is present are transcribed at high levels. Concept 18.2 Eukaryotic gene expression is regulated at many stages • Like unicellular organisms, the tens of thousands of genes in the cells of multicellular eukaryotes turn on and off in response to signals from their internal and external environments. • Gene expression must be controlled on a long-term basis during cellular differentiation. Differential gene expression is the expression of different genes by cells with the same genome. • A typical human cell probably expresses about 20% of its genes at any given time. ○ Highly specialized cells, such as nerves or muscles, express a tiny fraction of their genes. ○ Although all the cells in an organism contain an identical genome, the subset of genes expressed in the cells of each type is unique. • The differences between cell types are due to differential gene expression, the expression of different genes by cells with the same genome. • The function of any cell, whether a single-celled eukaryote or a particular cell type in a multicellular organism, depends on the appropriate set of genes being expressed. ○ Problems with gene expression and control can lead to imbalance and disease, including cancer. • Our understanding of the mechanisms that control gene expression in eukaryotes has been enhanced by new research methods, including advances in DNA technology. • In all organisms, a common control point for gene expression is at transcription, often in response to signals coming from outside the cell. ○ For this reason, the term gene expression is often equated with transcription. • With their greater complexity, eukaryotes have opportunities for controlling gene expression at additional stages. Chromatin modifications affect the availability of genes for transcription. • The DNA of eukaryotic cells is packaged with proteins in a complex called chromatin. ○ The basic unit of chromatin is the nucleosome. • The location of a gene’s promoter relative to nucleosomes and to the sites where the DNA attaches to the chromosome scaffold or nuclear lamina affect whether the gene is transcribed. • Genes of densely condensed heterochromatin are usually not expressed. • Chemical modifications of the histone proteins and DNA of chromatin play a key role in chromatin structure and gene expression. • The N-terminus of each histone molecule in a nucleosome protrudes outward from the nucleosome. ○ These histone tails are accessible to various modifying enzymes, which catalyze the addition or removal of specific chemical groups. • Histone acetylation (addition of an acetyl group, —COCH3) and deacetylation of lysines in histone tails appear to play a direct role in the regulation of gene transcription. • Acetylation of lysines neutralizes their positive charges and reduces the binding of histone tails to neighboring nucleosomes, easing access for transcription proteins. ○ Some of the enzymes responsible for acetylation or deacetylation are associated with or are components of transcription factors that bind to promoters. • Thus, histone acetylation enzymes may promote the initiation of transcription not only by modifying chromatin structure but also by binding to and recruiting components of the transcription machinery. • Other chemical groups, such as methyl and phosphate groups, can be reversibly attached to amino acids in histone tails. ○ The attachment of methyl groups (—CH3) to histone tails leads to condensation of chromatin. ○ The addition of a phosphate group (phosphorylation) to an amino acid next to a methylated amino acid has the opposite effect. • The recent discovery that modifications to histone tails can affect chromatin structure and gene expression has led to the histone code hypothesis. ○ This hypothesis proposes that specific combinations of modifications, as well as the order in which they have occurred, determine chromatin configuration. ○ Chromatin configuration in turn influences transcription. DNA methylation reduces gene expression. • While some enzymes methylate the tails of histone proteins, other enzymes methylate certain bases in DNA itself, usually cytosine. ○ DNA methylation occurs in most plants, animals, and fungi. • Inactive DNA is generally more highly methylated than actively transcribed regions. ○ For example, the inactivated mammalian X chromosome is heavily methylated. ○ Individual genes are usually more heavily methylated in cells where they are not expressed. Removal of extra methyl groups can turn on some of these genes. • In some species, DNA methylation is responsible for the long-term inactivation of genes during cellular differentiation. ○ Deficient DNA methylation leads to abnormal embryonic development in organisms as different as mice and the plant Arabidopsis. • Once methylated, genes usually stay that way through successive cell divisions in a given individual. • Methylation enzymes recognize sites on one strand that are already methylated and correctly methylate the daughter strand after each round of DNA replication. • This methylation pattern accounts for genomic imprinting, in which methylation turns off either the maternal or paternal alleles of certain mammalian genes at the start of development. • The chromatin modifications just discussed do not alter the DNA sequence, and yet they may be passed along to future generations of cells. • Inheritance of traits by mechanisms not directly involving the nucleotide sequence is called epigenetic inheritance. • The molecular systems for chromatin modification may well interact with each other in a regulated way. ○ In Drosophila, experiments suggest that a particular histone-modifying enzyme recruits a DNA methylation enzyme to one region and that the two enzymes collaborate to silence a particular set of genes. ○ Working in the opposite order, proteins have also been found that bind to methylated DNA and then recruit histone deacetylation enzymes. ○ Thus, a dual mechanism, involving both DNA methylation and histone deacetylation, can repress transcription. • Researchers are amassing more and more evidence for the importance of epigenetic information in the regulation of gene expression. ○ Epigenetic variations may explain why one identical twin acquires a genetically based disease, such as schizophrenia, while another does not, despite their identical genomes. ○ Alterations in normal patterns of DNA methylation are seen in some cancers, where they are associated with inappropriate gene expression. • Enzymes that modify chromatin structure are integral parts of the cell’s machinery for regulating transcription. Transcription initiation is controlled by proteins that interact with DNA and with each other. • Chromatin-modifying enzymes provide initial control of gene expression by making a region of DNA more available or less available for transcription. • A cluster of proteins called a transcription initiation complex assembles on the promoter sequence at the upstream end of the gene. ○ One component, RNA polymerase II, transcribes the gene, synthesizing a primary RNA transcript or pre-mRNA. ○ RNA processing includes enzymatic addition of a 5¢ cap and a poly-A tail, as well as splicing out of introns to yield a mature mRNA. • Multiple control elements are associated with most eukaryotic genes. ○ Control elements are noncoding DNA segments that serve as binding sites for protein transcription factors. ○ Control elements and the transcription factors they bind are critical to the precise regulation of gene expression in different cell types. • To initiate transcription, eukaryotic RNA polymerase requires the assistance of proteins called transcription factors. • General transcription factors are essential for the transcription of all protein-coding genes. ○ Only a few general transcription factors independently bind a DNA sequence such as the TATA box within the promoter. ○ Others are involved in protein-protein interactions, binding each other and RNA polymerase II. • Only when the complete initiation complex has been assembled can the polymerase begin to move along the DNA template strand to produce a complementary strand of RNA. • The interaction of general transcription factors and RNA polymerase II with a promoter usually leads to only a slow rate of initiation and the production of few RNA transcripts. • In eukaryotes, high levels of transcription of particular genes depend on the interaction of control elements with specific transcription factors. • Some control elements, named proximal control elements, are located close to the promoter. • Distal control elements, grouped as enhancers, may be thousands of nucleotides away from the promoter or even downstream of the gene or within an intron. • A given gene may have multiple enhancers, each active at a different time or in a different cell type or location in the organism. ○ Eukaryotic gene expression can be altered by the binding of specific transcription factors, either activators or repressors, to the control elements of enhancers. • Two structural elements are common to many activator proteins: a DNA-binding domain and one or more activation domains. ○ Activation domains bind other regulatory proteins or components of the transcription machinery to facilitate transcription. • Protein-mediated bending of DNA brings bound activators in contact with a group of mediator proteins that interact with proteins at the promoter. ○ These interactions help assemble and position the initiation complex on the promoter. • Eukaryotic repressors can inhibit gene expression by blocking the binding of activators to their control elements or to components of the transcription machinery. ○ Other repressors bind directly to control-element DNA, turning off transcription even in the presence of activators. • Some activators and repressors act indirectly to influence chromatin structure. ○ Some activators recruit proteins that acetylate histones near the promoters of specific genes, promoting transcription. ○ Some repressors recruit proteins that deacetylate histones, reducing transcription or silencing the gene. • Recruitment of chromatin-modifying proteins seems to be the most common mechanism of repression in eukaryotes. The control of transcription in eukaryotes depends on the binding of activators to DNA control elements. • The number of different nucleotide sequences found in control elements is surprisingly small: about a dozen. • On average, each enhancer is composed of about ten control elements, each of which can bind to only one or two specific transcription factors. ○ The particular combination of control elements in an enhancer may be more important than the presence of a unique control element in regulating transcription of the gene. • Even with only a dozen control element sequences, a large number of combinations are possible. • A particular combination of control elements is able to activate transcription only when the appropriate activator proteins are present, at a precise time during development or in a particular cell type. • The use of different combinations of control elements allows fine regulation of transcription with a small set of control elements. • In prokaryotes, coordinately controlled genes are often clustered into an operon with a single promoter and other control elements upstream. ○ The genes of the operon are transcribed into a single mRNA and translated together. • In contrast, very few eukaryotic genes are organized this way. • More commonly, co-expressed genes coding for the enzymes of a metabolic pathway are scattered over different chromosomes. ○ Coordinate gene expression depends on the association of a specific control element or combination of control elements with every gene of a dispersed group. ○ A common group of transcription factors binds to all the genes in the group, promoting simultaneous gene transcription. • For example, a steroid hormone enters a cell and binds to a specific receptor protein in the cytoplasm or nucleus, forming a hormone–receptor complex that serves as a transcription activator. ○ Every gene whose transcription is stimulated by that steroid hormone has a control element recognized by that hormone–receptor complex. • Other signal molecules control gene expression indirectly by triggering signal-transduction pathways that lead to activation of transcription. ○ The principle of coordinate regulation is the same: Genes with the same control elements are activated by the same chemical signals. • Systems for coordinating gene regulation probably arose early in evolutionary history. • The nucleus has a defined architecture and regulated movements of chromatin. • Recent techniques allow researchers to cross-link and identify regions of chromosomes that associate with each other during interphase. • Loops of chromatin extend from individual chromosomal territories into specific sites in the nucleus. ○ Different loops from the same chromosome and loops from other chromosomes congregate in such sites, some of which are rich in RNA polymerases and other transcription-associated proteins. ○ These sites are likely areas specialized for a common function or transcription factories. Post-transcriptional mechanisms play supporting roles in the control of gene expression. • Regulatory mechanisms that operate after transcription allow a cell to rapidly fine-tune gene expression in response to environmental changes, without altering its transcriptional patterns. ○ RNA processing in the nucleus and the export of mRNA to the cytoplasm provide opportunities for gene regulation that are not available in prokaryotes. • In alternative RNA splicing, different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns. ○ Regulatory proteins specific to a cell type control intron-exon choices by binding to regulatory sequences within the primary transcript. • Alternative RNA splicing significantly expands the repertoire of a set of genes. ○ It may explain the surprisingly low number of human genes: similar to those of a soil worm, a mustard plant, or a sea anemone. ○ Between 75% and 100% of human genes that have multiple exons probably undergo alternative splicing. ○ The extent of alternative splicing increases the number of possible human proteins, likely correlated with complexity of form. • The life span of an mRNA molecule is an important factor in determining the pattern of protein synthesis. ○ Prokaryotic mRNA molecules are typically degraded after only a few minutes, while eukaryotic mRNAs typically last for hours, days, or weeks. ○ In red blood cells, mRNAs for hemoglobin polypeptides are unusually stable and are translated repeatedly. • Nucleotide sequences in the untranslated trailer region (UTR) at the 3¢ end affect mRNA stability. ○ Transferring such a sequence from a short-lived mRNA to a normally stable mRNA results in quick mRNA degradation. Translation presents an opportunity for the regulation of gene expression. • The initiation of translation of an mRNA can be blocked by regulatory proteins that bind to specific sequences within the 5¢ or 3¢ UTR of the mRNA, preventing ribosome attachment. • The mRNAs present in the eggs of many organisms lack poly-A tails of sufficient length to allow initiation of translation. ○ During embryonic development, a cytoplasmic enzyme adds more adenine nucleotides so that translation can begin at the appropriate time. • Translation of all the mRNAs in a eukaryotic cell may be regulated simultaneously by the activation or inactivation of the protein factors required to initiate translation. ○ This mechanism starts the translation of mRNAs that are stored in eggs. ○ Just after fertilization, translation is triggered by the sudden activation of translation initiation factors, resulting in a burst of protein synthesis. • Some plants and algae store mRNAs during periods of darkness. Light triggers the reactivation of the translational apparatus. The final opportunities for controlling gene expression occur after translation. • Often, eukaryotic polypeptides are processed to yield functional proteins. ○ For example, cleavage of pro-insulin forms the active hormone. • Many proteins must undergo chemical modifications before they are functional. ○ Regulatory proteins may be activated or inactivated by the reversible addition of phosphate groups. ○ Proteins destined for the surface of animal cells acquire sugars. • Regulation may occur at any of the steps involved in modifying or transporting a protein. • The length of time a protein functions before it is degraded is strictly regulated. ○ Proteins such as the cyclins that regulate the cell cycle must be relatively short-lived. • To mark a protein for destruction, the cell attaches a small protein called ubiquitin to it. ○ Giant protein complexes called proteasomes recognize and degrade the tagged proteins. • Mutations making specific cell cycle proteins impervious to proteasome degradation can lead to cancer. • The scientists worked out the regulated process of protein degradation won the 2004 Nobel Prize in Chemistry. Concept 18.3 Noncoding RNAs play multiple roles in controlling gene expression • Only 1.5% of the human genome codes for proteins. Of the remainder, only a very small fraction consists of genes for ribosomal RNA and transfer RNA. • Until recently, it was assumed that most of the rest of the DNA was untranscribed. Recent data have challenged that assumption, however. ○ Study of a region comprising 1% of the human genome found that over 90% of the region was transcribed. ○ Introns accounted for only a fraction of this transcribed, nontranslated RNA. • A significant amount of the genome may be transcribed into non–protein-coding RNAs (or noncoding RNAs or ncRNAs), including a variety of small RNAs. • A large, diverse population of RNA molecules may play crucial roles in regulating gene expression in the cell. MicroRNAs can bind to complementary sequences in mRNA molecules. • In the past few years, researchers have found small, single-stranded RNA molecules called microRNAs (miRNAs) that bind to complementary sequences in mRNA molecules. • miRNAs are formed from longer RNA precursors that fold back on themselves to form one or more short, double-stranded hairpin structures stabilized by hydrogen bonding. • An enzyme called Dicer cuts each hairpin into a short, double-stranded fragment of about 22 nucleotide pairs. • One of the two strands is degraded. The other strand (miRNA) associates with a protein complex and directs the complex to any mRNA molecules that have a complementary sequence of 7-8 nucleotides. • The miRNA–protein complex either degrades the target mRNA or blocks its translation. • Expression of up to one-half of all human genes may be regulated by miRNAs. • The phenomenon of inhibition of gene expression by RNA molecules is called RNA interference (RNAi). • Injecting double-stranded RNA molecules into a cell somehow turns off expression of a gene with the same sequence as the RNA. ○ This RNA interference is due to small interfering RNAs (siRNAs), similar in size and function to miRNAs and are generated by similar mechanisms in eukaryotic cells. • Both miRNAs and siRNAs can associate with the same proteins, with similar results. ○ The distinction between these molecules is the nature of the precursor molecules from which they are formed. ○ Each miRNA forms from a single hairpin in the precursor RNA, while multiple siRNAs form from a longer, double-stranded RNA molecule. • Cellular RNAi pathways lead to the destruction of RNAs and may have originated as a natural defense against infection by double-stranded RNA viruses. ○ The fact that the RNAi pathway can also affect the expression of nonviral cellular genes may reflect a different evolutionary origin for the RNAi pathway. • Many species, including mammals, possess long, double-stranded precursors to small RNAs that interfere with various steps in gene expression. Small RNAs can remodel chromatin and silence transcription. • Small RNAs can cause remodeling of chromatin structure. ○ In yeast, siRNAs are necessary for the formation of heterochromatin at the centromeres of chromosomes. • An RNA transcript produced from DNA in the centromeric region of the chromosome is copied into double-stranded RNA by a yeast enzyme and then processed into siRNAs. ○ The siRNAs associate with a protein complex, targeting the complex back to the RNA sequences made from the centromeric sequences of DNA. ○ The proteins in the complex recruit enzymes to modify the chromatin, turning it into the highly condensed centromeric heterochromatin. • A newly discovered class of small ncRNAs, called piwi-associated RNAs (piRNAs) also induce formation of heterochromatin, blocking expression of parasitic DNA elements in the genome known as transposons. ○ piRNAs, 24–31 nucleotides in length, are processed from single-stranded RNA precursors. ○ In germ cells of many animal species, piRNAs help re-establish appropriate methylation patterns in the genome during gamete formation. • Chromatin remodeling not only blocks expression of large regions of the chromosome; RNA-based mechanisms may also block the transcription of specific genes. ○ Some plant miRNAs have sequences that bind to gene promoters and can repress transcription; piRNAs can also block expression of specific genes. ○ In some cases, miRNAs and piRNAs activate gene expression. • Small ncRNAs regulate gene expression at multiple steps and in many ways. ○ Extra levels of gene regulation may allow evolution of a higher degree of complexity of form. ○ An increase in the number of miRNAs encoded in the genomes of species may have allowed morphological complexity to increase over evolutionary time. • A survey of species suggests that siRNAs evolved first, followed by miRNAs and later piRNAs, which are found only in animals. ○ While there are hundreds of types of miRNA, there appear to be many thousands of types of piRNAs, allowing the potential for very sophisticated gene regulation by piRNAs. • Many ncRNAs play important roles in embryonic development, the ultimate example of an elaborate program of regulated gene expression. Concept 18.4 A program of differential gene expression leads to the different cell types in a multicellular organism • In the development of most multicellular organisms, a single-celled zygote gives rise to cells of many different types. ○ Each type has a different structure and corresponding function. ○ Cells of different types are organized into tissues, tissues into organs, organs into organ systems, and organ systems into the whole organism. • Thus, the process of embryonic development must give rise not only to cells of different types but also to higher-level structures arranged in a particular way in three dimensions. A genetic program is expressed during embryonic development. • As a zygote develops into an adult organism, its transformation results from three interrelated processes: cell division, cell differentiation, and morphogenesis. • Through a succession of mitotic cell divisions, the zygote gives rise to many cells. ○ Cell division alone would produce only a great ball of identical cells. • During development, cells become specialized in structure and function, undergoing cell differentiation. • Different kinds of cells are organized into tissues and organs. • The physical processes that give an organism its shape constitute morphogenesis, the “creation of form.” • Cell division, cell differentiation, and morphogenesis have their basis in cellular behavior. ○ Morphogenesis can be traced back to changes in the shape and motility of cells in the various embryonic regions. ○ The activities of a cell depend on the genes it expresses and the proteins it produces. ○ Because almost all cells in an organism have the same genome, differential gene expression results from differential gene regulation in different cell types. • Why are different sets of activators present in different cell types? • One important source of information early in development is the egg’s cytoplasm, which contains both RNA and proteins encoded by the mother’s DNA, distributed unevenly in the unfertilized egg. • Maternal substances that influence the course of early development are called cytoplasmic determinants. ○ These substances regulate the expression of genes that affect the developmental fate of the cell. ○ After fertilization, the cell nuclei resulting from mitotic division of the zygote are exposed to different cytoplasmic environments. ○ The set of cytoplasmic determinants a particular cell receives helps determine its developmental fate by regulating expression of the cell’s genes during cell differentiation. • The other important source of developmental information is the environment around the cell, especially signals impinging on an embryonic cell from nearby cells. ○ In animals, these signals include contact with cell-surface molecules on neighboring cells and the binding of growth factors secreted by neighboring cells. • These signals cause changes in the target cells, a process called induction. ○ The molecules conveying these signals within the target cells are cell-surface receptors and other proteins expressed by the embryo’s own genes. ○ The signal molecules send a cell down a specific developmental path by causing a change in its gene expression that eventually results in observable cellular changes. Cell differentiation is due to the sequential regulation of gene expression. • During embryonic development, cells become visibly different in structure and function as they differentiate. • The earliest changes that set a cell on a path to specialization show up only at the molecular level. ○ Molecular changes in the embryo drive the process, called determination, which leads to the observable differentiation of a cell. • Once it has undergone determination, an embryonic cell is irreversibly committed to its final fate. ○ If a determined cell is experimentally placed in another location in the embryo, it will differentiate as if it were in its original position. • The outcome of determination—observable cell differentiation—is caused by the expression of genes that encode tissue-specific proteins. ○ These proteins give a cell its characteristic structure and function. • Differentiation begins with the appearance of cell-specific mRNAs and is eventually observable in the microscope as changes in cellular structure. • In most cases, the pattern of gene expression in a differentiated cell is controlled at the level of transcription. • Cells produce the proteins that allow them to carry out their specialized roles in the organism. ○ For example, liver cells specialize in making albumin, while lens cells specialize in making crystalline. ○ Skeletal muscle cells have high concentrations of proteins specific to muscle tissues, such as a muscle-specific version of the contractile proteins myosin and actin, as well as membrane receptor proteins that detect signals from nerve cells. • Muscle cells develop from embryonic precursors that have the potential to develop into a number of alternative cell types. ○ Although the committed cells are unchanged, they are now myoblasts. ○ Eventually, myoblasts begin to synthesize muscle-specific proteins and fuse to form mature, elongated, multinucleate skeletal muscle cells. • Researchers have worked out the events at the molecular level that lead to muscle cell determination by growing myoblasts in culture and analyzing them with molecular biology techniques. ○ Researchers isolated different genes, caused each to be expressed in a separate embryonic precursor cell, and looked for differentiation into myoblasts and muscle cells. ○ They identified several “master regulatory genes” that, when transcribed and translated, commit the cells to become skeletal muscle. • One of these master regulatory genes is called myoD. ○ myoD encodes MyoD protein, a transcription factor that binds to specific control elements in the enhancers of various target genes and stimulates their expression. ○ Some target genes for MyoD encode for other muscle-specific transcription factors. ○ MyoD also stimulates expression of the myoD gene itself, helping to maintain the cell’s differentiated state. • All the genes activated by MyoD have enhancer control elements recognized by MyoD and are thus coordinately controlled. • The secondary transcription factors activate the genes for proteins such as myosin and actin to confer the unique properties of skeletal muscle cells. • The MyoD protein is capable of changing fully differentiated fat and liver cells into muscle cells. • Not all cells can be transformed by MyoD, however. ○ Nontransforming cells may lack a combination of regulatory proteins in addition to MyoD. Pattern formation sets up the embryo’s body plan. • Cytoplasmic determinants and inductive signals contribute to pattern formation, the development of spatial organization in which the tissues and organs of an organism are all in their characteristic places. • Pattern formation begins in the early embryo, when the major axes of an animal are established. • Before specialized tissues and organs form, the relative positions of a bilaterally symmetrical animal’s three major body axes (anterior-posterior, dorsal-ventral, right-left) are established. • The molecular cues that control pattern formation, positional information, are provided by cytoplasmic determinants and inductive signals. ○ These signals tell a cell its location relative to the body axes and to neighboring cells and determine how the cell and its progeny will respond to future molecular signals. • Studies of pattern formation in Drosophila melanogaster have established that genes control development and have identified the key roles of specific molecules in defining position and directing differentiation. • Combining anatomical, genetic, and biochemical approaches in the study of Drosophila development, researchers have discovered developmental principles common to many other species, including humans. • Fruit flies and other arthropods have a modular construction. ○ An ordered series of segments make up the three major body parts: the head, thorax (with wings and legs), and abdomen. • Cytoplasmic determinants in the unfertilized egg provide positional information for two developmental axes (anterior-posterior and dorsal-ventral axis) before fertilization. • The Drosophila egg develops in the female’s ovary, surrounded by ovarian cells called nurse cells and follicle cells that supply the egg cell with nutrients, mRNAs, and other substances. • During fruit fly development, the egg forms a segmented larva, which goes through three larval stages. ○ The fly larva forms a pupal cocoon within which it metamorphoses into an adult fly. • In the 1940s, Edward B. Lewis used mutants to investigate Drosophila development. ○ Bizarre developmental mutations were on the fly’s genetic map, providing the first concrete evidence that genes somehow direct the developmental process. ○ These homeotic genes control pattern formation in the late embryo, larva, and adult. • In the late 1970s, Christiane Nüsslein-Volhard and Eric Weischaus set out to identify all the genes that affect segmentation in Drosophila. They faced three problems. • First, because Drosophila has about 13,700 genes, there could be either only a few genes affecting segmentation or so many that the pattern would be impossible to discern. • Second, mutations that affect segmentation are likely to be embryonic lethals, leading to death at the embryonic or larval stage. ○ Flies with embryonic lethal mutations never reproduce, and cannot be bred for study. ○ Nüsslein-Volhard and Wieschaus focused on recessive mutations that could be propagated in heterozygous flies. • Third, because of maternal effects on axis formation in the egg, the researchers also needed to study maternal genes. • After exposing flies to mutagenic chemicals, Nüsslein-Volhard and Wieschaus looked for dead embryos and larvae with abnormal segmentation. ○ Through appropriate crosses, they found heterozygotes carrying embryonic lethal mutations. • Nüsslein-Volhard and Wieschaus identified 1,200 genes essential for embryonic development. ○ About 120 of these were essential for normal segmentation. • The researchers grouped the genes by general function, mapped them, and cloned many of them. • In 1995, Nüsslein-Volhard, Wieschaus, and Lewis were awarded a Nobel Prize. Gradients of maternal molecules in the early Drosophila embryo control axis formation. • Cytoplasmic determinants produced under the direction of maternal effect genes are deposited in the unfertilized egg. • A maternal effect gene is a gene that, when mutant in the mother, results in a mutant phenotype in the offspring, regardless of the offspring’s own genotype. ○ In fruit fly development, maternal effect genes encode proteins or mRNA that are placed in the egg while it is still in the ovary. ○ When the mother has a mutation in a maternal effect gene, she makes a defective gene product (or none at all) and her eggs will not develop properly when fertilized. • Maternal effect genes are also called egg-polarity genes because they control the orientation of the egg and consequently the fly. ○ One group of genes sets up the anterior-posterior axis, while a second group establishes the dorsal-ventral axis. • One gene called bicoid affects the front half of the body. • An embryo whose mother has a mutant bicoid gene lacks the front half of its body and has duplicate posterior structures at both ends. ○ This suggests that the product of the mother’s bicoid gene is essential for setting up the anterior end of the fly and might be concentrated at the future anterior end. • This is a specific version of the morphogen gradient hypothesis, in which gradients of morphogens establish an embryo’s axes and other features. • Using DNA technology and biochemical methods, researchers were able to clone the bicoid gene and use it as a probe for bicoid mRNA in the egg. ○ As predicted, the bicoid mRNA is concentrated at the extreme anterior end of the egg cell. • After the egg is fertilized, bicoid mRNA is transcribed into protein, which diffuses from the anterior end toward the posterior, resulting in a gradient of proteins in the early embryo. ○ Injections of pure bicoid mRNA into various regions of early embryos resulted in the formation of anterior structures at the injection sites. • The bicoid research is important for three reasons. 1. It identified a specific protein required for some of the earliest steps in pattern formation. 2. It increased our understanding of the mother’s role in the development of an embryo. 3. It demonstrated a key developmental principle: a gradient of molecules can determine polarity and position in the embryo. • Maternal mRNAs are crucial during development of many species. ○ In Drosophila, gradients of specific proteins encoded by maternal mRNAs determine the posterior and anterior ends and establish the dorsal-ventral axis. • Later, positional information encoded by the embryo’s genes establishes a specific number of correctly oriented segments and triggers the formation of each segment’s characteristic structures. Concept 18.5 Cancer results from genetic changes that affect cell cycle control • Cancer is a set of diseases in which cells escape the control mechanisms that normally regulate cell growth and division. ○ The gene regulation systems that go wrong during cancer are the systems that play important roles in embryonic development and immune response. • The genes that normally regulate cell growth and division during the cell cycle include genes for growth factors, their receptors, and the intracellular molecules of signaling pathways. ○ Mutations altering any of these genes in somatic cells can lead to cancer. ○ The agent of such changes can be random spontaneous mutations or environmental influences such as chemical carcinogens, X-rays, and some viruses. Proto-oncogenes can become oncogenes, contributing to the development of cancer. • Cancer-causing genes, oncogenes, were initially discovered in viruses. ○ Close counterparts have been found in the genomes of humans and other animals.å • Normal versions of cellular genes, called proto-oncogenes, code for proteins that stimulate normal cell growth and division. • A proto-oncogene becomes an oncogene following genetic changes that lead to an increase in the proto-oncogene’s protein production or in the intrinsic activity of each protein molecule. ○ These genetic changes include movement of DNA within the genome, amplification of the proto-oncogene, and point mutations in a control element or the proto-oncogene itself. • Cancer cells frequently have chromosomes that have been broken and rejoined incorrectly. ○ A fragment may be moved to a location near an active promoter or other control element. • Amplification increases the number of copies of the proto-oncogene in the cell. • A point mutation in the promoter or enhancer of a proto-oncogene may increase its expression. • A point mutation in the coding sequence may lead to translation of a protein that is more active or longer-lived. • All of these mechanisms can lead to abnormal stimulation of the cell cycle, putting the cell on the path to malignancy. Mutations to tumor-suppressor genes may contribute to cancer. • The normal products of tumor-suppressor genes inhibit cell division. • Some tumor-suppressor proteins normally repair damaged DNA, preventing the accumulation of cancer-causing mutations. • Other tumor-suppressor proteins control the adhesion of cells to each other or to an extracellular matrix, which is crucial for normal tissues and often absent in cancers. • Still others are components of cell-signaling pathways that inhibit the cell cycle. ○ Decreases in the normal activity of a tumor-suppressor protein may contribute to cancer. • The proteins encoded by many proto-oncogenes and tumor-suppressor genes are components of cell-signaling pathways. • Mutations in the products of two key genes, the ras proto-oncogene and the p53 tumor-suppressor gene, occur in 30% and over 50% of human cancers, respectively. • The Ras protein, the product of the ras gene, is a G protein that relays a growth signal from a growth factor receptor on the plasma membrane to a cascade of protein kinases. ○ At the end of the pathway is the synthesis of a protein that stimulates the cell cycle. • Many ras oncogenes have a point mutation that leads to a hyperactive version of the Ras protein that trigger the kinase cascade in the absence of growth factor, resulting in excessive cell division. • The p53 gene, named for its 53,000-dalton protein product, is a tumor-suppressor gene. ○ The p53 protein is a specific transcription factor for the synthesis of several cell cycle-inhibiting proteins. ○ The p53 gene has been called the “guardian angel of the genome.” • Once activated by DNA damage, the p53 protein functions as an activator for several genes. ○ The p53 protein can activate the p21 gene, whose product halts the cell cycle by binding to cyclin-dependent kinases, allowing time for DNA repair. ○ p53 also activates expression of a group of miRNAs, which inhibit the cell cycle. ○ The p53 protein can also turn on genes directly involved in DNA repair. ○ When DNA damage is irreparable, the p53 protein can activate “suicide genes” whose protein products cause cell death by apoptosis. • A mutation that knocks out the p53 gene can lead to excessive cell growth and cancer. Multiple mutations underlie the development of cancer. • More than one somatic mutation is generally needed to produce the changes characteristic of a full-fledged cancer cell. • If cancer results from an accumulation of mutations, and if mutations occur throughout life, then the longer we live, the more likely we are to develop cancer. • Colorectal cancer, with 140,000 new cases and 50,000 deaths in the United States each year, illustrates a multistep cancer path. ○ The first sign is often a polyp, a small benign growth in the colon lining. ○ The cells of the polyp look normal but divide unusually frequently. ○ Through gradual accumulation of mutations that activate oncogenes and knock out tumor-suppressor genes, the polyp can develop into a malignant tumor. ○ A ras oncogene and a mutated p53 tumor-suppressor gene are usually involved. • About a half dozen DNA changes must occur for a cell to become fully cancerous. • These changes usually include the appearance of at least one active oncogene and the mutation or loss of several tumor-suppressor genes. ○ Because mutant tumor-suppressor alleles are usually recessive, mutations must knock out both alleles. ○ Most oncogenes behave like dominant alleles and require only one mutation. Cancer can run in families. • The fact that multiple genetic changes are required to produce a cancer cell helps explain the predispositions to cancer that run in families. ○ An individual inheriting an oncogene or a mutant allele of a tumor-suppressor gene is one step closer to accumulating the necessary mutations for cancer to develop. • Geneticists are devoting much effort to finding inherited cancer alleles so that a predisposition to certain cancers can be detected early in life. • About 15% of colorectal cancers involve inherited mutations. • Many of these mutations affect the tumor-suppressor gene adenomatous polyposis coli or APC. ○ Normal functions of the APC gene include regulation of cell migration and adhesion. ○ Even in patients with no family history of the disease, APC is mutated in about 60% of colorectal cancers. • Between 5% and 10% of breast cancer cases show an inherited predisposition. ○ Breast cancer is the second most common type of cancer in the United States, annually striking more than 180,000 women and leading to 40,000 deaths. • Mutations in one gene, BRCA1, increase the risk of breast and ovarian cancer. ○ Mutations in BRCA1 and the related gene BRCA2 are found in at least half of inherited breast cancers. • A woman who inherits one mutant BRCA1 allele has a 60% probability of developing breast cancer before age 50 (versus a 2% probability in an individual with two normal alleles). ○ Both BRCA1 and BRCA2 are considered tumor-suppressor genes because their wild-type alleles protect against breast cancer and their mutant alleles are recessive. • BRCA1 and BRCA2 proteins function in the cell’s DNA damage repair pathway. ○ BRCA2, in association with another protein, helps repair breaks that occur in both strands of DNA. • Because DNA breakage can contribute to cancer, the risk of cancer can be lowered by minimizing exposure to DNA-damaging agents, such as ultraviolet radiation in sunlight and the chemicals found in cigarette smoke. • In addition to mutations and other genetic alterations, a number of tumor viruses can cause cancer in various animals, including humans. ○ In 1911, Peyton Rous, an American pathologist, discovered a virus that causes cancer in chickens. ○ The Epstein-Barr virus, which causes infectious mononucleosis, has been linked to several types of cancer in humans, notably Burkitt’s lymphoma. ○ Papillomaviruses are associated with cancer of the cervix, and a virus called HTLV-1 causes a type of adult leukemia. • Worldwide, viruses seem to play a role in about 15% of the cases of human cancer. • Viruses can interfere with gene regulation in several ways if they integrate their genetic material into a cell’s DNA. ○ Viral integration may donate an oncogene to the cell, disrupt a tumor-suppressor gene, or convert a proto-oncogene to an oncogene. ○ Some viruses produce proteins that inactivate p53 and other tumor-suppressor proteins, making the cell more likely to become cancerous. Lecture Outline for Reece et al., Campbell Biology, 10th Edition, Copyright © 2014 Pearson Education, Inc

AULA DE MUTAÇÕES

Java Interlude 6: Mutable and Immutable Objects

znaczenie mitozy, mejozy i apoptozy

Philippine Movements for Nationalism: Gomburza, Cavite Mutiny, and Propaganda

Modul Mumtaz Tingkatan 5: Bidang Akhlak

GASP Refresher and Isolation of GASP Mutants

Los Mutantes Vocab

BSCI222 - mutants

Reading in Philippine History: The Two Faces of the Cavite Mutiny

Cavite Mutiny of 1872

Cavite Mutiny Accounts

Immutable vs. Mutable Objects and Scope of Variables

Charakterystyka materiałów: metali, ceramiki, polimerów i kompozytów

1 Introduction The search of one’s home, person or vehicle with or without a warrant may, depending on the circumstances, constitute a violation of the right to privacy. Our courts determine whether state action (police conduct) constitutes a violation of a complainant’s right to privacy or any other right by applying two tests. First, the courts must determine the scope of the right to privacy and consider whether the police conduct breached the complainant’s right to privacy; if not, that would be the end of the matter. However, if the police conduct did breach the complainant’s right to privacy, the courts would continue with the second test. The second test determines whether the police conduct is justified because they, for example, acted in terms of the provisions of the Criminal Procedure Act 51 of 1977 (as amended). This second test is referred to as the limitations analysis under s 36 of the Constitution. If the police conduct cannot be justified in terms of s 36 because the police officer, for example, exceeded the powers granted to him or her in terms of the Criminal Procedure Act, the complainant would have succeeded in establishing that his or her right to privacy has been violated. (Section 36 is included in the appendices at the end of this book.) Search, seizure, and matters related thereto are regulated by Chapter 2 (s 19 and sections that follow) of the Criminal Procedure Act. The Criminal Procedure Act embodies the general provisions with regard to searching; specific provisions are contained in many other acts. It is impossible to refer to all these acts. Section 19 of the Criminal Procedure Act states explicitly that Chapter 2 of the Act shall not derogate from any power conferred by any other Act to enter any premises or to search any person, container or premises or to seize any matter, to declare any matter forfeited or to dispose of any matter. 2 The scope and content of the right to privacy The right to privacy seeks to protect the right not to have one’s person or home searched, one’s property searched, one’s possessions seized, or the privacy of one’s communications infringed. The scope of the right to privacy is determined by the concept of a ‘legitimate expectation of privacy’ (Bernstein v Bester 1996 (2) SA 751 (CC) at [75]). Our courts do not define the right to privacy; instead, they apply the notion of a ‘spectrum’ of privacy protection, consisting of a small circle, followed by a number of bigger circles surrounding the central circle. The small central circle represents the intimate core of privacy, relating to, for example, what one does in one’s bedroom, and wider circles beyond this central core represent social interactions of a less private nature such as, for example, travelling in public transport. Interferences with the central core may only be justified in exceptional circumstances, whereas interferences with the outer circles, which are far removed from the centre of privacy, are less demanding to defend (Minister of Police v Kunjana 2016 (2) SACR 473 (CC) [2016] ZACC 21 at [17]). In other words, the more a search and seizure interferes with the central core of privacy, the more challenging it will be to justify such interference. Privacy is also intrinsically linked to human dignity, which constitutes one of the most significant values our constitution seeks to uphold (Investigating Directorate: Serious Economic Offences v Hyundai Motor Distributors Page 192 (Pty) Ltd 2001 (1) SA 545 (CC) at [18]; Thint (Pty) Ltd v National Director of Public Prosecutions 2008 (2) SACR 421 (CC) [2008] ZACC 13 at [77]). 3 Articles that are susceptible to seizure The Criminal Procedure Act confers powers to search only where the object of the search is to find a certain person or to seize an article which falls into one of three classes of articles, including documents, which may be seized by the state in terms of the provisions of the Criminal Procedure Act. These are— (1) articles which are concerned in or are on reasonable grounds believed to be concerned in the commission or suspected commission of an offence, whether within the Republic or elsewhere—s 20(a); (2) articles which may afford evidence of the commission or suspected commission of an offence, whether within the Republic or elsewhere—s 20(b); or (3) articles which are intended to be used or are on reasonable grounds believed to be intended to be used in the commission of an offence—s 20(c). Under normal circumstances an article or document falling into one of the abovementioned categories may be seized by the state. The only exceptions relate to documents which are privileged and in respect of which the holder of the privilege has not yet relinquished his or her privilege. An example of this would be where the document consists of a communication between an attorney and his or her client. Such a document is subject to legal professional privilege and may not be handed in to the court without the consent of the client. If the state had the power to seize such a document the whole object of the privilege would be defeated. In Prinsloo v Newman 1975 (1) SA 481 (A) at 493F–G and SASOL III (Edms) Bpk v Minister van Wet en Orde 1991 (3) SA 766 (T) it was accordingly held that such a document may not be seized. 4 Search in terms of a search warrant 4.1 General rule Searches and seizures should, whenever possible, be conducted only in terms of a search warrant, issued by a judicial officer such as a magistrate or judge—cf the wording of s 21(1). This will ensure that an independent judicial officer stands between the citizen and the law enforcement official (police official)—Park-Ross v Director: Office for Serious Economic Offences 1995 (2) SA 148 (C) at 172. For this reason the provisions governing the issue of search warrants require that the judicial officer must himself or herself decide whether or not there are ‘reasonable grounds’ for the search. 4.2 The discretion of a judicial officer to issue a warrant In deciding whether there are reasonable grounds for the search, the judicial officer exercises a discretion similar to the discretion he or she exercises in granting bail, remanding a case or sentencing an accused, and so forth. This discretion must be exercised in a judicial manner. This simply means that the judicial officer must exercise the discretion in a reasonable and regular manner, in accordance Page 193 with the law and while taking all relevant facts into account—Minister of Safety and Security v Van der Merwe 2011 (5) SA 61 (CC). Before issuing a search warrant the judicial officer must therefore decide whether the article that will be searched for is one which may be seized in terms of s 20 and whether it appears from the affidavit that there are reasonable grounds to believe that the article is present at a particular place (Minister of Safety and Security v Van der Merwe, above). As far as the concept of ‘reasonable grounds’ is concerned, see the discussion of the requirement of reasonableness in Chapter 6. Government action is required to be objectively and demonstrably reasonable. This laudable principle was unfortunately undermined by the decision in Divisional Commissioner of SA Police, Witwatersrand Area v SA Associated Newspapers 1966 (2) SA 503 (A), where it was held that the merits of the decision by a justice of the peace, that there are objective grounds upon which a warrant may be issued, may not be contested in court (contrary to where a search without a warrant is conducted by the police). The decision to issue a search warrant may, in terms of this decision, be set aside only on administrative grounds (such as mala fides on the part of the judicial officer) and not on the merits. This decision was quoted with approval in Cresto Machines v Die Afdeling-Speuroffisier SA Polisie, Noord-Transvaal 1972 (1) SA 376 (A) 396; cf further Cine Films (Pty) Ltd v Commissioner of Police 1971 (4) SA 574 (W) 581. Mogoeng CJ, in Minister of Safety and Security v Van der Merwe 2011 (5) SA 61 (CC), held (at [55]) that a judicial officer must ensure that the following prerequisites are complied with before authorising a warrant: (a) the warrant must mention the statutory provision in terms of which it is authorised; (b) it must identify the searcher; (c) it must clearly describe the scope of the powers granted to the searcher; (d) it must identify the person, container or premises to be searched; (e) it must clearly describe the article to be searched for and seized; (f) it must mention the offence being investigated; (g) it must state the name of the person being investigated. 4.3 General search warrants The procedure with regard to search warrants is governed by s 21. Subsection (1) provides that, subject to ss 22, 24 and 25 (see below), an article referred to in s 20 shall be seized only by virtue of a search warrant issued— (a) by a magistrate or justice, if it appears to such magistrate or justice from information on oath that there are reasonable grounds for believing that any such article is in the possession or under the control of any person, or upon or at any premises within his area of jurisdiction; or (b) by a judge or judicial officer presiding at criminal proceedings, if it appears to such judge or judicial officer that any such article in the possession or under the control of any person or upon or at any premises is required in evidence at such proceedings. Page 194 Section 21(2) stipulates that a warrant must direct a police official to seize the article in question and must to that end authorise such police official to search any person identified in the warrant, or to enter and search any premises identified in the warrant and to search any person found on or at such premises. See also Extra Dimension v Kruger NO 2004 (2) SACR 493 (T). In Minister of Safety and Security v Van der Merwe 2011 (5) SA 61 (CC) at [56] Mogoeng CJ set out the following guidelines that our courts must take into account when assessing the validity of search and seizure warrants. These are whether— (a) the person who authorised a warrant has authority to do so; (b) the person (mentioned in (a)) has jurisdiction to authorise a warrant; (c) the affidavit contains information regarding the existence of the jurisdictional facts (meaning a reasonable suspicion that a crime has been committed and reasonable grounds to believe that objects connected to crime may be found on the premises); (d) the scope (boundaries) of the search that must be conducted are clear and not overbroad or vague; (e) the searched person’s constitutional rights are not unnecessarily interfered with. Mogoeng CJ also mentioned that the terms of a warrant must be strictly interpreted, in order to protect the searched person against excessive interference by the state (Van der Merwe above at [56]; also Thint (Pty) Ltd v National Director of Public Prosecutions; Zuma v National Director of Public Prosecutions 2008 (2) SACR 421 (CC)). The decision in Goqwana v Minister of Safety and Security 2016 (1) SACR 384 (SCA) explained the importance of the prerequisites and guidelines mentioned in the Van der Merwe case above, by highlighting three important points: first, the reason why the identity of the searcher must be mentioned in a warrant is to ensure accountability in case the searcher abuses his or her power (at [25]; secondly, where the search is in connection with a statutory offence, as opposed to a common-law offence, the relevant statute and section must be mentioned, in order to enable both the searcher and the searched person to know exactly what the warrant has been authorised for (at [29]); and thirdly, the affidavit in support of the warrant should accompany the warrant and should be handed to the searched person in case he or she wants to challenge the validity of the warrant (at [31]). Even though s 21 does not require that the suspected offence be set out in the warrant, it is desirable to do so in order to facilitate the interpretation of the warrant— Minister of Safety and Security v Van der Merwe above at [56]. The powers conferred by s 21 constitute grave infringements of the privacy of the individual. To limit this infringement, s 21(3)(a) provides that a search warrant must be executed (ie acted upon) by day, unless the judicial officer who issues it gives written authorisation for it to be executed by night. A warrant may be issued and be executed on a Sunday, as on any other day, and remains in force until it is executed or is cancelled by the person who issued it or, if such person is not available, by a person with like authority—s 21(3)(b). Page 195 4.4 Warrants to maintain internal security and law and order 4.4.1 Background In Wolpe v Officer Commanding South African Police, Johannesburg 1955 (2) SA 87 (W) members of the police entered a hall in which a conference was being held by the ‘South African Congress of Democrats’ in co-operation with other organisations. The chairman requested the police to leave the meeting and explained that it was a private meeting. The police refused to do so. Members of the Congress of Democrats thereupon brought an urgent application to the court for an interdict prohibiting the police from attending the meeting. They argued that the police do not have greater powers than any other individual, except in so far as they are vested with wider powers by statute. The application was refused. Rumpff J held that the basic duties of the police are not confined to those mentioned in statutes. The basic duties of the police flow from the nature of the police as a civil force in the state. According to him it was not the intention of the legislature by s 7 of the (previous) Police Act to revoke the basic duties of the police and to supplant them with statutory duties. The judge dealt fully with the duties of the police and came to the conclusion that if there were a suspicion that as a result of the holding of a meeting, a disturbance of public order would occur on the same day, the police are entitled to attend the meeting in order to prevent a disturbance of order, even though the meeting was private. If the police had reasonable grounds for suspecting that seditious speeches would be made at such meeting, and that their presence would prevent them from being made, it would be a reasonable exercise of their duty for the police to attend the meeting, notwithstanding the fact that there would be no immediate disturbance of the peace. According to Rumpff J the liberty of the individual must in such circumstances give way to the interests of the state. He suggested, however, that the legislature should define the duties and powers of the police in connection with the combating of what the state from time to time considered to be dangerous. This eventually led to the inclusion of s 25 in the current Criminal Procedure Act. 4.4.2 Warrant in terms of s 25 Section 25(1) stipulates that if it appears to a magistrate or justice from information on oath that there are reasonable grounds for believing— (a) that the internal security of the Republic or the maintenance of law and order is likely to be endangered by or in consequence of any meeting which is being held or is to be held in or upon any premises within his area of jurisdiction; or (b) that an offence has been or is being or is likely to be committed or that preparations or arrangements for the commission of any offence are being or are likely to be made in or upon any premises within his area of jurisdiction, he may issue a warrant authorising a police official to enter the premises in question at any reasonable time for the purpose— (i) of carrying out such investigations and of taking such steps as such police official may consider necessary for the preservation of the internal security of Page 196 the Republic or for the maintenance of law and order or for the prevention of any offence; (ii) of searching the premises or any person in or upon the premises for any article referred to in s 20 and which such police official on reasonable grounds suspects to be in or upon or at the premises or upon such person; and (iii) of seizing any such article. A warrant under sub-s (1) may be issued on any day and shall remain in force until it is executed or is cancelled by the person who issued it or, if such person is not available, by a person with like authority—sub-s (2). A warrant issued in terms of s 25(1)(i) confers wide powers on the police. The fact that a police official who acts in terms thereof may take any steps that he or she ‘may consider necessary’ for the preservation of the internal security of the Republic or for the maintenance of law and order or for the prevention of any offence means that the police official’s discretion in this respect will have to be considered subjectively. The question will therefore not be whether the steps the police officer took were really necessary, but whether such officer subjectively thought that he or she had reason to believe that they were necessary. Moreover, this provision sets no legal boundaries within which such discretion powers may be exercised, thus leaving ample room for the abuse of power (see Minister of Police and Others v Kunjana 2016 (2) SACR 473 (CC)). 4.5 General information requirements with regard to warrants When law enforcement officials act in terms of a warrant, it is desirable that the subject involved has access to the document which authorises an infringement upon his or her private rights. The effective execution of legal remedies, such as an interdict, mandament van spolie, or even the institution of the rei vindicatio, is to a large extent dependent on this (see Tsegeya v Minister of Police (unreported, Mthatha High Court case no 2746/2018 21 August 2018). Section 21(4) therefore stipulates that a police official who executes a warrant in terms of ss 21 or 25 must, once the warrant has been executed and upon the request of any person whose rights are affected by the search or seizure of an object in terms of the warrant, provide such a person with a copy of the warrant (see Goqwana v Minister of Safety and Security, above, which goes even further by requiring that the supporting affidavit to the warrant be handed to the person whose property forms the subject of the search). We are of the opinion that two objections may be raised against this subsection, which is laudable in other respects. In the first place a copy of the warrant should, whenever possible (ie if the subject is present at the time of the execution of the warrant), be provided before the search and/or seizure. Secondly, the delivery of a copy of the warrant should not be dependent on the request of the subject. Many subjects, through lack of knowledge of the law, will not make such a request and thus act to their potential detriment. Page 197 5 Search without a warrant 5.1 Introduction Although it is preferable, as mentioned above, that searches should only be conducted on the authority of a search warrant issued by a judicial officer, it is quite conceivable that circumstances may arise where the delay in obtaining such warrant would defeat the object of the search. It is therefore necessary that provision be made for the power to conduct a search without a warrant. However, police officials intending to conduct a search and seizure should always be conscious of the cautionary remark made by Madlala J in Minister of Police v Kunjana 2016 (2) SACR 473 (CC) at [27]: It should not be forgotten that exceptions to the warrant requirement should not become the rule. While search warrants empower only police officials to conduct searches and to seize objects, both private persons and police officials are empowered to conduct searches or to seize objects without a warrant. 5.2 Powers of the police 5.2.1 Consent to search and/or to seize In terms of s 22(a) a police official may search any person, container or premises for the purpose of seizing any article referred to in s 20, if the person concerned consents to the search for and the seizure of the article in question, or if the person who may consent to the search of the container or premises consents to such search and the seizure of the article in question. 5.2.2 Search and seizure where a delay would defeat the object thereof In terms of s 22(a) a police official may search any person, container or premises for the purpose of seizing any article referred to in s 20, if the police official believes on reasonable grounds that— (1) a search warrant will be issued to him or her under s 21(1)(a) if he or she applies for such warrant; and (2) the delay in obtaining such warrant would defeat the object of the search. The belief of the police official must be objectively justified on the facts—NDPP v Starplex 47 CC [2008] 4 All SA 275 (C). Section 25(3) allows a police official to act without a warrant if he or she believes on reasonable grounds that— (1) a warrant will be issued to him or her under s 25(1)(a) or (b) if he applies for such warrant; and (2) the delay in obtaining such warrant would defeat the object thereof. A police official’s powers in terms of s 25(3) are the same as the powers he or she would have had by virtue of a warrant (cf (i) to (iii) above and NDPP v Starplex 47 CC above. In Starplex a search warrant was issued to search certain premises under s 33(5) of the Immigration Act, on the grounds that information had been received that a group of foreign nationals issued false documents and permits. During the search a significant amount of foreign currency was discovered and Page 198 consequently seized. The seizure of the money was challenged on the ground that the search warrant did not authorise its seizure. The court rejected this contention on the basis that suspects could quickly hide away the money from the authorities in order to prevent its seizure, and the money was reasonably suspected as being illegal foreign currency. Expecting the police to obtain a new warrant under those circumstances would defeat the object of the search. In the result, the court held that the money was lawfully seized in terms of s 22(2).) 5.2.3 Search and seizure for the purposes of border control Section 13(6) of the South African Police Service Act 68 of 1995 empowers a police official, for the purposes of border control or to control the import or export of any goods, to search without a warrant any person, premises, other place, vehicle, vessel, ship, aircraft or any receptacle of whatever nature, at any place in the Republic within ten kilometres or any reasonable distance from any border between the Republic and any foreign state, or from any airport or at any place in the territorial waters of the Republic or inside the Republic within ten kilometres from such territorial waters, and to seize anything found upon such person or upon or at or in such premises, other place, vehicle, vessel, ship, aircraft or receptacle which may lawfully be seized. 5.2.4 Search and seizure in a cordoned-off area The National or a Provincial Commissioner of the South African Police Service may, in terms of s 13(7) of the South African Police Service Act 68 of 1995, where it is reasonable in the circumstances in order to restore public order or to ensure the safety of the public in a particular area, authorise that the particular area or any part thereof be cordoned off. This is done by issuing a written authorisation which must also set out the purpose of the cordoning off. Any member of the Service may, in order to achieve the purpose set out in the authorisation, without a warrant, search any person, premises, vehicle or any receptacle or object of whatever nature in that area and seize any article referred to in s 20 of the Criminal Procedure Act found by him or her upon such person or in that area: provided that a member executing a search in terms of s 13(7) must, upon demand of any person whose rights are or have been affected by the search or seizure, exhibit to him or her a copy of the written authorisation by such commissioner. 5.2.5 Search and seizure at a roadblock or checkpoint The National or a Provincial Commissioner of the South African Police Service may, in terms of s 13(8) of the South African Police Service Act 68 of 1995, where it is reasonable in the circumstances in order to exercise a power or perform a function of the Service, in writing authorise a member under his or her command to set up a roadblock or roadblocks on any public road in a particular area or to set up a checkpoint or checkpoints at any public place in a particular area. Any member of the Service may, without a warrant, search any vehicle and any person in or on such vehicle at such a roadblock or checkpoint and seize any article referred to in s 20 of the Criminal Procedure Act found by him or her upon such person or in or on such vehicle. A member executing a search in terms of s 13(8) Page 199 must, upon demand by any person whose rights are or have been affected by the search or seizure, exhibit to him or her a copy of the written authorisation by such commissioner. Section 13(8)(d) authorises any member of the Service to set up a roadblock on a public road without a written authorisation in certain specified circumstances where the delay in obtaining a written authorisation would defeat the object of the setting up of the roadblock. 5.2.6 Search and seizure in terms of the Drugs and Drug Trafficking Act 140 of 1992 Search for and seizure of substances in terms of the Drug and Drug Trafficking Act was, until recently, controlled by s 11 of the Act. Prior to the declaration of constitutional invalidity in Minister of Police v Kunjana 2016 (2) SACR 473 (CC), s 11(1) of the Act read as follows: (1) A police official may— (a) if he has reasonable grounds to suspect that an offence under this Act has been or is about to be committed by means or in respect of any scheduled substance, drug or property, at any time— (i) enter or board and search any premises, vehicle, vessel or aircraft on or in which any such substance, drug or property is suspected to be found; (ii) search any container or other thing in which any such substance, drug or property is suspected to be found; (b) if he has reasonable grounds to suspect that any person has committed or is about to commit an offence under this Act by means or in respect of any scheduled substance, drug or property, search or cause to be searched any such person or anything in his possession or custody or under his control: Provided that a woman shall be searched by a woman only; (c) if he has reasonable grounds to suspect that any article which has been or is being transmitted through the post contains any scheduled substance, drug or property by means or in respect of which an offence under this Act has been committed, notwithstanding anything to the contrary in any law contained, intercept or cause to be intercepted either during transit or otherwise any such article, and open and examine it in the presence of any suitable person; (d) question any person who in his opinion may be capable of furnishing any information as to any offence or alleged offence under this Act; (e) subject to s 15 of the Regulation of Interception of Communications and Provision of Communication-related Information Act, 2002, require from any person who has in his or her possession or custody or under his or her control any register, record or other document which in the opinion of the police official may have a bearing on any offence or alleged offence under this Act, to deliver to him or her then and there, or to submit to him or her at such time and place as may be determined by the police official, any such register, record or document; (f) examine any such register, record or document or make an extract therefrom or a copy thereof, and require from any person an explanation of an entry in any such register, record or document; (g) seize anything which in his opinion is connected with, or may provide proof of, a contravention of a provision of this Act. The constitutional validity of the entire s 11 was challenged by the applicant in Kunjana v Minister of Police [2015] ZAWCHC 198 (High Court judgment). On consideration the High Court, per Veldhuizen J, concluded that the application directed at the entire s 11 was too broad and restricted the relief to s 11(1)(a) and (g). The High Court declared the provisions invalid and the matter was placed before Page 200 the Constitutional Court for confirmation of the order of invalidity (Minister of Police v Kunjana 2016 (2) SACR 473 (CC). The Constitutional Court applied the limitation clause to s 11(1)(a) and (g). On consideration of the nature and extent of the limitation the court remarked: The impugned provisions are broad. Section 11(1)(a) and (g) of the Drugs Act does not circumscribe the time, place nor manner in which the searches and seizures can be conducted. . . (at [21]). Further, section 11(1)(a) grants police officers the power to search warrantless at ‘any time’ ‘any premises, vehicle, vessel or aircraft’ and ‘any container’ in which substances or drugs are suspected to be found (at [22]). I agree with the applicants’ contention that the impugned provisions leave police officials without sufficient guidelines with which to conduct the inspection within legal limits (at [23]). The court next considered whether there are less restrictive means to achieve the purpose of s 11(1)(a) and (g) and reasoned that— [s]ection 11(1)(a) implies that warrantless searches of private homes may be conducted pursuant to it. The more a search intrudes into the ‘inner sanctum’ of a person (such as their home) the more the search infringes their privacy right. The provisions are also problematic as they do not preclude the possibility of a greater limitation of the right to privacy than is necessitated by the circumstances, with the result that police officials may intrude in instances where an individual’s reasonable expectation of privacy is at its apex. The court contended that constitutionally adequate safeguards must exist to justify circumstances in which legislation allows for warrantless searches. These safeguards are clearly provided by s 22 of the Criminal Procedure Act, which provides less restrictive means to restrict the right to privacy during search and seizure procedures. The Constitutional Court accordingly confirmed the constitutional invalidity of ss 11(1)(a) and (g). Warrantless search and seizure should not be a norm of criminal procedure, which is confirmed by the various court interventions in, for example, the Customs and Excise Act 91 of 1964, Estate Agency Affairs Act 112 of 1976 and Financial Intelligence Centre Act 38 of 2001, wherein the validity of warrantless search and seizure provisions were challenged (see also Estate Agency Affairs Board v Auction Alliance (Pty) Ltd 2014 (3) SA 106 (CC) and Gaertner v Minister of Finance 2014 (1) SA 442 (CC)). Search and seizure under the provisions of a warrant should form the basis of any such action because— [a] warrant is not a mere formality. It is a mechanism employed to balance an individual’s right to privacy with the public interest in compliance with and enforcement of regulatory provisions. A warrant guarantees that the State must be able, prior to an intrusion, to justify and support intrusions upon individuals’ privacy under oath before a judicial officer. Further, it governs the time, place and scope of the search. This softens the intrusion on the right to privacy, guides the conduct of the inspection, and informs the individual of the legality and limits of the search. Our history provides evidence of the need to adhere strictly to the warrant requirement unless there are clear and justifiable reasons for deviation (Gaertner at [69]). The above notwithstanding, there are instances where warrantless search and seizure is clearly indicated, but they must be conducted under the prescriptions of s 22 of the Criminal Procedure Act where there is a need for swift action. Page 201 5.3 Powers of the occupiers of premises In terms of s 24 of the Criminal Procedure Act any person who is lawfully in charge or occupation of any premises and who reasonably suspects that— (1) stolen stock or produce, as defined in any law relating to the theft of stock or produce, is on or in the premises concerned, or that (2) any article has been placed thereon or therein or is in the custody or possession of any person upon or in such premises in contravention of any law relating to— (a) intoxicating liquor, (b) dependence-producing drugs, (c) arms and ammunition, or (d) explosives, may at any time, if a police official is not readily available, enter such premises for the purpose of searching such premises and any person thereon or therein, and if any such stock, produce or article is found, he shall take possession thereof and forthwith deliver it to a police official. 5.4 Search for the purpose of effecting an arrest In the event of a search of premises in order to find and arrest a suspect, exactly the same powers are conferred on police officials and private persons. In terms of s 48, a peace officer or private person who is authorised by law to arrest another in respect of any offence and who knows or reasonably suspects such other person to be on any premises may, if he or she first audibly demands entry into such premises and states the purpose for which he or she seeks entry and fails to gain entry, break open and enter and search such premises for the purpose of effecting the arrest. A number of court decisions on the forerunner of s 48 still apply to s 48. These include the following: In Jackelson 1926 TPD 685 it was held that persons who had ejected a police official who had entered premises without first demanding and being refused admission could not be convicted of obstructing such police official in the execution of his duty. In Rudolf 1950 (2) SA 522 (C) a police official had seen a man drinking wine in a public place and wished to arrest him. The man ran into a house pursued by the constable and was arrested at the foot of the stairs. The two accused attempted to rescue the wine-drinker from the custody of the police official. It was contended, inter alia, that the wine-drinker had not been in ‘lawful custody’ because the police official had made an unlawful entry when he entered the premises without first demanding admission in terms of the predecessor to the present s 48. The court held, however, that the constable had been justified, in the circumstances of the case, in entering the house to arrest the wine-drinker and consequently the arrest was a lawful one. The court distinguished Jackelson mainly on the ground that the accused in Jackelson had ejected the constable before he had effected an arrest, while in Rudolf the arrest had been effected when the accused attempted to rescue the wine-drinker— cf also Andresen v Minister of Justice 1954 (2) SA 473 (W). Page 202 5.5 Review of the actions of the person conducting the search In cases where action is taken without a warrant, the actions of the person conducting the search may be reviewed by a court of law on the merits—cf eg LSD Ltd v Vachell 1918 WLD 127. 6 Search of an arrested person This matter is governed by s 23. That section provides that on the arrest of any person, the person making the arrest may, provided that he or she is a peace officer, search the person arrested and seize any article referred to in s 20 which is in the possession or under the control of the arrested person. If the person making the arrest is not a peace officer, he or she has no power to search the arrested person. The person making the arrest does, however, have the power to seize an article referred to in s 20 which is in the possession or under the control of the arrested person. Such a private person must forthwith hand the seized article to a police official. (This also applies to a peace officer who is not a police official). On the arrest of any person, the person effecting the arrest may place in safe custody any object found on the arrested person which may be used to cause bodily harm to himself or herself or to others—s 23(2). 7 The use of force in order to conduct a search The use of force is regulated by s 27 as far as this chapter is concerned. In terms of s 27(1), a police official who may lawfully search any person or any premises may use such force as may be reasonably necessary to overcome any resistance against such search or against entry of the premises, including the breaking of any door or window of such premises. In terms of a proviso to this subsection, such a police official shall first audibly demand admission to the premises and state the purpose for which he or she seeks to enter such premises. This proviso does not apply where the police official concerned is, on reasonable grounds, of the opinion that any article which is the subject of the search may be destroyed or disposed of if the proviso is first complied with—s 27(2). The latter is known as the ‘no-knock clause’ and is particularly helpful to the police where the search will be for small objects which may easily be swallowed or flushed down a toilet. 8 General requirement of propriety with regard to searching Section 29 stipulates that a search of any person or premises shall be conducted with strict regard to decency and order, and a woman shall be searched by a woman only, and if no female police official is available, the search shall be made by any woman designated for the purpose by a police official. In order to comply with the requirement of propriety in terms of s 29, it can certainly be assumed, in terms of the general principles of the interpretation of statutes, that a male person should be searched by a male only. We suggest that any divergence from these provisions would be unlawful and that ‘consent’ by Page 203 the person being searched by the opposite sex would be invalid as it would be contra bonos mores. 9 Unlawful search The provisions of the law of criminal procedure which regulate searching are ‘double- functional’: From a substantive law viewpoint they constitute grounds of justification, while in formal law they regulate the procedural steps whereby an eventual legal decision may validly be reached. In the latter case the principle of legality (cf Chapter 1) and the concept of ‘legal guilt’ are of paramount importance in that, unless a ‘factually guilty’ person can be brought to justice within the bounds of the provisions of the law of criminal procedure (ie in strict compliance with the prescribed rules and limitations), he or she must, according to law, go free—see Chapter 1. The question now arises as to what the effect is of unlawful action by the authorities with regard to these pre-trial procedural rules. As these provisions are double- functional, it is necessary to differentiate between the substantive and formal law consequences: 9.1 Formal-law consequences of unlawful action by the authorities In terms of s 35(5) of the Constitution, evidence obtained in a manner that violates any right in the Bill of Rights must be excluded if the admission of that evidence would render the trial unfair or otherwise be detrimental to the administration of justice. This so-called ‘exclusionary rule’ gives a clear signal to all state officials that it is futile to gather evidence in an unlawful manner, since evidence so obtained will not be taken into account by the court in reaching a verdict. (See Motloutsi 1996 (1) SA 584 (C) and Mayekiso 1996 (2) SACR 298 (C).) Evidence obtained in terms of an invalid search warrant may be excluded under s 35(5) of the Constitution. Heaney 2016 JDR 0806 (GP) is an appeal where the accused, in his capacity as a member of a close corporation, challenged the validity of a search warrant. This challenge was based on the grounds that the affidavit in support of the authorisation of the warrant was unsigned and not commissioned; it authorised the station commander (and not a specific police officer) to conduct the search (without mentioning a police station); and the offence and article which had to be seized was not clearly identified. On appeal, the court declared the warrant invalid. The court held that the execution of this invalid warrant violated the right to privacy of the accused. The right to privacy is a right guaranteed under s 14 of the Constitution and the evidence was accordingly obtained in a manner that violated a right guaranteed in the Bill of Rights. This, the court held, triggered s 35(5) of the Constitution, calling upon a court to determine whether the admission of the evidence obtained in this manner would render the trial unfair or otherwise be detrimental to the administration of justice. In the result, the evidence seized was excluded under s 35(5) and the appeal was upheld (see also Oforah 2013 JDR 1956 (GSJ). The admissibility of evidence under s 35(5) must, in general, be determined during a trial within a trial (Tandwa 2008 (1) SACR 613 (SCA). Page 204 The exclusionary rule is discussed in more detail in handbooks dealing with the law of evidence and was briefly dealt with in Chapter 1. 9.2 Substantive-law consequences of unlawful action by the authorities This aspect is governed partly by s 28. In terms of sub-s (1), a police official commits an offence and is liable on conviction to a fine or to imprisonment for a period not exceeding six months— (1) when he acts contrary to the authority of a search warrant issued under s 21 or a warrant issued under s 25(1); or (2) when he, without being authorised thereto, (a) searches any person or container or premises or seizes or detains any article; or (b) performs any act contemplated in s 25(1). Subsection (2) stipulates that where any person falsely gives information on oath for the purposes of ss 21(1) or 25(1) and a warrant is issued and executed on such information, and such person is in consequence of such false information convicted of perjury, the court convicting such person may, upon the application of any person who has suffered any damage in consequence of the unlawful entry, search or seizure, or upon the application of the prosecutor acting on the instructions of such a person, award compensation in respect of such damage, whereupon the provisions of s 300 shall mutatis mutando of ownership. The object is therefore no longer regarded as stolen property and may then be restored to the person from whom it was forfeited, if he or she bought it from another. The former person is then considered as ‘the person who may lawfully possess it’—Mdunge v Minister of Police 1988 (2) SA 809 (N); Datnis Motors (Midlands) (Pty) Ltd v Minister of Law and Order 1988 (1) SA 503 (N). After the conviction of an accused, the court has, in terms of s 35(1) and in certain circumstances, the power to forfeit to the state certain objects which were used in the commission of the particular crime. Section 36 deals with the circumstances under which, and the manner in which, articles may be delivered to the police of another country. There are also various other laws that make provision for search, seizure and the forfeiture of articles, eg s 29(5) of the National Prosecuting Authority Act 32 of 1998 (cf Thint (Pty) Ltd v National Director of Public Prosecutions; Zuma v National Director of Public Prosecutions 2008 (2) SACR 421 (CC)) and the Prevention of Organised Crime Act 121 of 1998, which provides for confiscation, preservation and forfeiture orders: A confiscation order (s 18) consists therein that a court, convicting an accused of an offence, may, on the application of the public prosecutor, enquire into any benefit which the accused may have derived from that offence (or any other offence of which the accused has been convicted at the same trial or any criminal activity sufficiently related to those offences) and may, in addition to any punishment which it may impose in respect of that offence, make an order against the accused for the payment to the state of any amount it considers appropriate. A preservation order (s 38) prohibits a person from dealing in any manner with any property which is an instrumentality of an offence—ie any property concerned Page 205 in the commission or suspected commission of an offence. Property only qualifies as an instrumentality if it is used to commit the offence and its use must be such that it plays a real and substantial part in the actual commission of the offence. The fact that a crime is committed at a certain place does not by itself make that place an instrumentality of the offence—Singh v National Director of Public Prosecutions 2007 (2) SACR 326 (SCA). A forfeiture order (s 48) is an order forfeiting to the state all or any of the property subject to a preservation of property order and is applied for by the national director of public prosecutions. An order of forfeiture may be made only if the deprivation in a particular case is proportionate to the ends at which the legislation is aimed, and distinctions between different classes of offence will feature heavily in that part of the enquiry. Although an order of forfeiture operates as both a penalty and a deterrent, its primary purpose is remedial. Forfeiture is likely to have its greatest remedial effect where crime has become a business. The Supreme Court of Appeal, accordingly, did not consider a motor vehicle driven whilst under the influence of alcohol ‘an instrumentality of an offence’ as contemplated under the Prevention of Organised Crime Act 121 of 1998—National Director of Public Prosecutions v Vermaak [2008] 1 All SA 448 (SCA). See also Shaik 2008 (1) SACR 1 (CC). Restitution should be distinguished from forfeiture. Restitution is dealt with in Chapter 19

5.2 Gene Mutations

HISTORY | CAVITE MUTINY

In the Round Tower at Jhansi (Indian Mutiny) Quotes

RPH cavite mutiny

BIO3060 #5 DNA Mutability: Mutation Types