Gene Regulation. Structure and Function = Genetic Information + EXPRESSION of info! Ch’s 18 & 19 (347-372). Review (RNA synthesis - pgs 309-313). Define: Promoter – Terminator – TATA Box – Intron – Exon –. Expression of genetic information controls: Cell Products Metabolism
Structure and Function =
Genetic Information + EXPRESSION of info!
Ch’s 18 & 19 (347-372)
TATA Box –
Why not always express?
DNA Regulatory Sequences – stretches of DNA that interact with regulatory proteins to control transcription
Regulatory Gene – sequence of DNA encoding a regulatory protein that controls the transcription of another gene or genes
Small molecules involved:
NEGATIVE CONTROL – When regulatory proteins inhibit gene expression by binding to DNA and blocking transcription
Cyclic AMP (cAMP) – molecule that accumulates when glucose is scarce (the inducer)
cAMP Receptor Protein (CRP) – protein that activates transcription when cAMP binds to its allosteric site
trpoperon – a repressible operon (inhibited by tryptophan- a repressor molecule)
lac operon – an inducible operon (stimulated by lactose – an inducer molecule)
So why different types of cells?
Genes are expressed (turned on or off) at different points of protein synthesis:
Transcription Factors (TF’s)
DNA upstream of promoters FOLDS back on itself and activates RNA polymerase to make mRNA (make the “gene”)
Proto-oncogenes – genes that code for proteins that stimulate normal cell growth and division
Oncogene – cancer causing gene
Mutations can cause a Proto-onco gene to change into an oncogene = stimulates many TF’s which stimulates cells to divide cancer (uncontrolled cell division)
Tumor-Suppressor Protein – a TF that promotes synthesis of the cell cycle- INHIBITING proteins
EX: p53 gene (“guardian angel of the genome”)
No p53, no inhibition of excess cell growth = CANCER