What is a mutation?	A random change to the genetic material.
What is a gene mutation?	A random change to base sequence of a gene.
What is a mutagen?	A substance or radiation that can cause a mutation.
What is a triplet?	A set of the 3 bases in DNA.
What is a point mutation?	A substitution of one DNA nucleotide for another, changing the triplet.
What are the 3 types of point mutation?	Silent, missense, nonsense
What is a silent point mutation?	A change to the DNA base triplet sequence that has no effect on the amino acid sequence in a protein.
What is a missense point mutation?	A change to the DNA base triplet sequence that leads to a change in the amino acid sequence in a protein.
What is a nonsense point mutation?	A change to the DNA base triplet sequence resulting in a termination triplet that leads to a truncated protein.
What is an indel mutation?	Insertion or deletion of one DNA nucleotide causing a frameshift.
What is a frameshift?	A change to every DNA base triplet downstream of an indel mutation.
Give an example of chromosome mutations.	Deletion / duplication / translocation / inversion
What is translocation in chromosome mutations?	A section of a chromosome breaks off and joins another non-homologous chromosome
What is inversion in chromosome mutations?	A section of a chromosome breaks off and is reversed before joining back onto the chromosome
What is the main example of gene expression control in prokaryotic cells?	lac operon
What is the function of the enzyme lactose permease?	Allows lactose to enter a bacterial cell.
What is the function of the enzyme beta-galactosidase?	Hydrolyses lactose into glucose and galactose.
What are the 4 components of the lac operon?	promoter, operator, lacZ structural gene, lacY structural gene
What is a structural gene?	A gene that codes for a functional protein.
What is a regulatory gene?	A gene that codes for a transcription factor which initiates/inhibits transcription of structural genes
What does the gene lacI code for?	Repressor protein
What does the gene lacZ code for?	Beta-galactosidase
What does the gene lacY code for?	Lactose permease
Where does the repressor protein bind in the lac operon?	Operator
Where does RNA polymerase bind in the lac operon?	Promoter
What is the inducer for the lac operon?	Lactose
What is the effect of lactose on the repressor protein?	Binds to the repressor protein, altering its shape and preventing it from binding to the operator region of the lac operon.
What conditions are necessary for the lac operon to be switched off?	Glucose present, lactose absent
What conditions are necessary for the lac operon to be switched on?	Glucose absent, lactose present
How can the action of RNA polymerase in lac operon be up-regulated?	Binding of the CRP-cAMP complex to RNA polymerase
How does cAMP levels within the cell affect the rate of lactose metabolism? Explain with reference to the lac operon.	Move glucose into cell decreases cAMP levels --> less transcription of lac operon --> less lactose metabolised
Give one way of transcriptional control in eukaryotic cells.	Converting heterochromatin to euchromatin
What is heterochromatin?	Tightly wound DNA around histones during cell division, visible under light microscope
What is euchromatin?	Loosely wound DNA during interphase, invisible under light microscope
At which state would the DNA be during cell division - heterochromatin or euchromatin?	Heterochromatin
At which stage of cell division would gene expression occur?	Interphase (G1 + G2)
Why can gene expression only occur with euchromatin?	Loosely wound DNA, therefore RNA polymerase can access/bind to genes
Explain how heterochromatin is converted to euchromatin.	Aceylation or phosphorylation of histones --> decrease its positive charge so negatively charged DNA is less attracted to it
Explain how euchromatin is converted to heterochromatin.	Methylation of histones --> make histones more hydrophobic to bind to each other more, wounding up the DNA more tightly
Give one way of transcriptional gene regulation.	Transcription factors
What are transcription factors?	Proteins or non-coding RNA that regulate the transcription of genes.
What 2 areas do transcription factors bind to?	Promoters, enhancers
What has happened if a transcription factor has repressed a gene?	The TF has attached to the promoter, preventing the attachment of RNA polymerase and expression of the gene.
What has happened if a transcription factor has up-regulated a gene?	The TF has attached to the enhancer, aiding the attachment of RNA polymerase to the promoter and expression of the gene.
Give one way of post-transcriptional gene regulation.	Maturing of mRNA through removal of introns.
What is an intron?	A non-coding region of DNA / RNA.
What is an exon?	A coding region of DNA / RNA.
What is pre-mRNA?	mRNA containing both introns and exons.
What is mature mRNA?	mRNA containing only exons (introns have been removed).
What is alternative splicing?	The joining of exons in a region of mRNA in different combinations resulting in one gene encoding more than one protein.
Give one way of translational gene regulation that up-regulates translation.	Activating initiation factors (through phosphorylation by kinases) to help mature mRNA to bind to ribosomes
Give one way of translational gene regulation that inihibits translation.	Degrade mRNA / Inhibition proteins bind to mRNA to prevent it from binding to ribosomes
Give one way of post-translational gene regulation.	Cyclic AMP to activate CRP or kinases / protein modification or further folding
What enzyme catalyses the formation of cyclic AMP from ATP?	Adenyl cyclase
What activates protein kinase A (PKA)?	Cyclic AMP
What is the function of protein kinase A (PKA)?	Activate enzymes / transcription factor proteins by phosphorylation.
What is a homeobox gene?	A gene controlling the anatomical development of an animal, plant or fungus.
Why are homeobox genes highly conserved in plants, animals and fungi?	Highly conserved anatomical structure ensures survival and reproduction
What is the homeobox sequence?	A sequence of 180 DNA base pairs found in all homeotic / homeobox genes --> codes for the homeodomain of regulatory proteins
What is the homeodomain sequence?	A sequence of 60 amino acids encoded by the homeobox sequence.
What is a Hox gene?	A homeobox / homeotic gene found only in animals.
What type of genes are homeotic / homeobox / Hox genes?	Regulatory
How many Hox gene clusters are found in humans?	4
What is apoptosis?	Programmed cell death
How is apoptosis different to cell death due to trauma?	Apoptosis does not involve hydrolytic enzymes.
What is a bleb in terms of apoptosis?	A protusion from a cell early on in apoptosis.
What are 4 cell signals that can induce apoptosis?	Cytokines, hormones, growth factors, nitric oxide
What are 4 uses of apoptosis in plant and animal tissue development?	Separation of limbs and digits in embryonic development, removal of anti-self T/B lymphocytes, immune response to viral infection, prevent tumour growth

Genetic control and Gene Expression