Biology 1002 Study Guide Pt2

Topics Covered from Midterm to Final Bio 1002

Gene Expression

The process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs

Operator

A segment of DNA that is a regulatory “switch”. Usually located within the promoter

Operon

The entire stretch of DNA that includes the operator, promotor, and the genes that they control

Regulatory Gene

Produces protein repressors

Repressor

Prevents gene transcription by binding to the operator and blocking RNA polymerase. (They can switch off Operons)

Inducer

inactivates the repressor to turn lac operon on

Corepressor

A molecule that cooperates with a repressor protein to switch an operon off

Repressible Operon

Usually on; binding of repressor to the operator shuts off transcription

Inducible Operon

Usually off; an inducer inactivates the repressor and turns transcription on

Tryptophan (trp) Operon

A set of genes in bacteria that code for enzymes needed to produce the amino acid Tryptophan

Lactose (lac) Operon

an inducible operon that contains genes encoding enzymes for hydrolysis and metabolism of lactose

Allolactose Operon

Present is lactose is present in the body. Acts as an Inducer

Activator

A protein that binds to an enhancer and stimulates transcription

cAMP (cyclic AMP)

A ring-shaped molecule made from ATP that is a common intracellular molecule (second messenger) in eukaryotic cells. It is a regulator of some bacterial operons.

CAP

When glucose is scarce, this is activated by binding cAMP. When it is activated, it attaches to the promotor of lac operon and increases the affinity of RNA polymerase, thus accelerating transcription

Histone Acetylation

When Acetyl groups are attached to positively charged lysine in histone tails. This loosens chromatin structure, promoting initiation of transcription

Methylation

Addition of methyl groups. This can condense chromatin

Epigenetic Inheritance

The transmission of information from on generation to the next that affects gene expression without altering the underlying DNA sequence

Transcription Initiation Complex

The completed assembly of transcription factors and RNA polymerase bound to a promotor

Control Elements

Segments of noncoding DNA that serve as transcription factor binding sites

Enhancers

A group of Distal control elements. May be far away from gene or located in an intron

Alternative RNA Splicing

Different mRNA molecules are produced from same primary transcript, depending on which segments are treated as exons and introns

Protein Degradation

A biological process in which cells break down old, damages proteins into smaller parts (amino acids) to be recycled or disposed of

Regulatory Sequences

A segment of DNA (or RNA) that acts as a control switch for a specific gene

Transposons

Move by means of a DNA intermediate and require a transposase enzyme

Retrotransposons

Move by means of an RNA intermediate, using a reverse transcriptase

Viruses

Infectious particles consisting of nucleic acid enclosed in a protein coat and, in some cases a membranous envelope

Capsids

The protein shell that encloses the viral genome. Built from protein subunits called Capsomeres

Viral Envelope

Derived from host cell membranes, contain a combination of viral and host cell molecules

Bacteriophage /// Phages

Viruses that infect bacteria

Lytic Cycle

Produces new phages and lyses the host cell (kills the host cell), releasing the progeny virus particles

Lysogenic Cycle

Replicates the phage genome without destroying the host cell

Virulent Phages

A phage that reproduces only by the lytic cycle

Temperate Phages

Phages that use both lytic and lysogenic cycles

Prophage

The integrated viral DNA that is incorporated into the host cell’s chromosome

DNA Viruses

A microorganism that uses DNA as its genetic material and relies on a host cell’s machinery to replicate

RNA Viruses

A microorganism that uses RNA as its genetic material

Retroviruses

Uses reverse transcriptase to copy their RNA genome into DNA. An RNA virus that replicates by transcribing its RNA into DNA and then inserting the DNA into a cellular chromosome; an important class of cancer-causing viruses.

Reverse Transcriptase

An enzyme encoded by certain viruses (retroviruses) that uses RNA as a template for DNA synthesis

CRISPR-Cas

A type of bacterial immune system. A technique for editing genes in living cells, involving a bacterial protein called Cas9 associated with a guide RNA complementary to a gene sequence of interest.

Somatic Cells

Any cells that are not gametes (Humans have 23 Pairs)

Gametes

Sperm and egg cells

Clone

A group of genetically identical individuals from the same parent

Diploid

Has two chromosome sets (for humans; 2n=26)

Haploid

A single set of chromosomes (Humans: n=23)

Karyotype

An ordered display of he chromosome pairs from a cell

Homologous Chromosomes (Homologs)

The two chromosomes in each pair. They are the same length and shape, and carry genes that control the same inherited characters but may have different alleles

Sex Chromosomes

Determine the sex of an individual, they are called X and Y

Autosomes

All other pairs of chromosomes (NOT the pair of sex chromosomes)

Synapsis

When Homologous chromosomes loosely pair up, aligned gene by gene

Crossing over

Exchange of DNA segments, occurs between nonsister chromatids

Chiasmata

X-shaped regions where crossing over occured

Character

Distinct heritable features (i.e. flower color)

Trait

Each variant for a character (i.e. a purple flower)

Allele

Alternative versions of a gene that may produce distinguishable phenotypic effects

Dominent

An allele who’s fully expressed in the phenotype of a heterozygote

Recessive

An allele whose phenotypic effect is not observed in a heterozygote

Homozygous

Having two identical alleles for a given gene

Heterozygous

Having two different alleles for a given gene.

Phenotype

The observable physical and physiological traits of an organism, which are determined by its genetic makeup.

Genotype

The genetic makeup, or set of alleles, of an organism

True-breeding

Plants that produce offspring of the same variety as themselves when they self pollinate (Homozygous for purple flower color)

Punnett Square

A diagram used in the study of inheritance to show the predicted genotypic results of random fertilization in genetic crosses between individuals of known genotype.

Testcross

Breeding the mystery individual with a homozygous recessive individual

Complete Dominance

Occurs when the phenotypes of the heterozygote and dominant homozygote are identical

Incomplete Dominance

Occurs when the phenotype of F1 hybrids is in between the phenotype of the two parental varieties

Codominance

Two dominant alleles affect the phenotype in separate, distinguishable ways

Pleiotrophy

Genes with multiple phenotypic effects

Multiple Alleles

Three of more alternative forms of a gene at specific locus within a population

Epistasis

A gene at one locus alters the phenotypic expression of a gene at the second locus

Polygenic Inheritance

An additive effect of two or more genes on a single phenotype

Carriers

Heterozygous individuals who carry the recessive allele but are phenotypically normal

Phenotypic Range

The total spectrum of possible physical traits that a single genotype can express when exposed to different environmental conditions

Multifactorial Characters

Genetic and environmental factors collectively influence phenotype (pH of soil affecting the color of hydrangea)

P Generation

Parental Generations

F1 Generation

Filial Generation (Kids)

F2 Generation

Filial Generation 2 (Grandkids)

Wild Type

The phenotype most commonly observed in natural populations; also refers to the individual with that phenotype.

Linked genes

Genes located on the same chromosome that tend to be inherited together

Sex-linked genes

A gene located on either sex chromosome

X-linked genes

Genes on the X chromosome. Has genes for many characters unrelated to sex

Y-linked genes

Genes on the Y chromosome; there are relatively few but they mainly encode genes related to sex determination

Barr body

A dense object lying along the inside of the nuclear envelope in cells of female mammals, representing a highly condensed, inactivated X chromosome

Genetic recombination

The production of offspring with combinations of traits differing from either parent

Map units

A unit of measurement of the distance between genes. One is equivalent to a 1% recombination frequency.

Recombination frequencies

The number of recombinant offspring divided by the number of total offspring (Multiply by 100)

Recombinant offspring

Offspring with nonparental phenotypes (a new combination of traits)

Nondisjunction

Pairs of homologous chromosomes do not separate normally during meiosis

Aneuploidy

Results from fertilization of gametes in which nondisjunction occurred

Offspring have an abnormal number of a particular chromosome

Monosomic

Zygote has only one copy of a particular chromosome

Trisomic

Zygote has three copies of a particular chromosome

Polyploidy

A condition in which an organism has more than 2 complete sets of chromosomes

Triploidy (3n): 3 sets of chromosomes

Tetraploidy (4n): 4 sets of chromosomes

Deletion

Removes a chromosomal segment

Duplication

Repeats a chromosomal segment

Inversion

Reverses a chromosomal segment

Translocation

Moves a chromosomal segment from one chromosome to a nonhomologous chromosome.

Adaptations

Inherited characteristics of organisms that enhance their survival and reproduction in specific environments

Natural Selection

A process in which individuals with favorable inherited traits are more likely to survive and reproduce

Artificial Selection

A process in which humans have modified other species by selecting and breeding individuals with desired traits

Homology