The promoter region is the site where RNA polymerase binds to initiate transcription.
Transcription factors are proteins that regulate gene expression by binding to specific DNA sequences near genes, either enhancing or inhibiting their activity.
Gene mutations:
Substitution - where one base is replaced by another
Insertion - Where a base is added and can cause a frameshift
Deletion - Where a base is removed and can cause a frameshift
These are point mutations that only affect a single base
Mutations can cause a change in the amino acid sequence of a protein, which can result in a change in the function of the protein
Missense mutation: A type of mutation where a point mutation results in a different amino acid being encoded
Nonsense mutation: A point mutation creates a premature stop codon, causing premature termination of translation
Most mutations have no effect due to the nature of DNA being degenerate meaning multiple bases can code for the same amino acid
Mutation: Change in the base sequence of DNA
Point mutation: Mutation affecting a single base
Mutagenic agent: anything that increases the rate of mutations
Chromosomal mutations:
Translocation: Codon is relocated elsewhere on the chromosome
Inversion: Codon detaches and reattaches in the inversed order
Duplication: Another copy of the same codon is added right after that codon
Regulatory genes are genes that code for proteins that restricts the synthesis of a transcription gene
Proteins from transcription genes are called transcription factors and in eukaryotes they stimulate expression and in prokaryotes the inhibit expression of structural genes
Transcriptional control
A) Without transcription factor
B) with transcription factor
C) promoter
D) operator
E) inhibits
F) stimulates
G) Repressor protein
H) transcription factor
Gene expression in eukaryotes:
Hormone enters the cell and diffuses into the nucleusHormone binds onto an inactive transcription factor and activates it
