The Control of Gene Expression Condensed Notes

The Control of Gene Expression
● Gene expression
○ Stem cells and totipotency
○ Regulation of protein synthesis
○ Gene expression and cancer
○ DNA-histone complex
○ Epigenetic control
○ Genome mutations
○ Genome project
■ DNA sequencing
■ Proteome
● Recombinant DNA technology


● Mutations are changes to the base sequence of DNA
○ Substitution
○ Deletion
○ Addition
○ Duplication
○ Inversion
○ Translocation
● Not all mutations affect the order of amino acids but some do
● Mutagenic agents increase the rate of mutation
○ High energy ionising radiation
○ Chemicals
● Stem cells
○ Multicellular organisms are made out of specialised cells
■ Totipotent (earliest)
■ Pluripotent
■ Multipotent
■ Unipotent (latest)
○ Stem cells differentiate to become specialised cells depending upon which genes
are expressed
○ Induced pluripotent stem cells (iPs)
● Regulating transcription and translation

, ○ Transcriptional factors




■ Bind to a promoter
■ Activators
■ Repressors
○ Oestrogen effect on gene transcription
○ RNA interference (RNAi) can inhibit translation of mRNA
■ siRNA (and miRNA in plants)
■ miRNA in mammals

● Epigenetics
○ Epigenetic control
○ Epigenetic marks
○ Epigenome
○ Acetylation
■ Addition of acetyl group means chromatin is less condensed so it's easier
for transcription factors and RNA polymerase to bind and for a gene to be
transcribed
■ Removal of acetyl group means chromatin is more condensed which
makes it more difficult for a gene to be transcribed
● Deacylation involves enzyme deacetylase
○ Methylation
■ Methyl group always attaches to CpG site
■ Increased methylation of DNA switches a gene off
● Epigenetics and cancer
○ Tumours
■ Cancerous/Malignant