Control of Gene Expression思维导图模板大纲
prokaryote
Gene expression
synthesis of a functional gene product
features
almost all cells contain a full DNA complement
selectively express
reason--changes in internal
and external signals
prolaction (from pituitary gland)
mammary gland, lactation stimulate
transcription of genes for milk proteins
housekeeping genes are expressed in all tissues
consistently expressed across tissues and
developmental stages
maintain basic cellular function
expression--tissue-dependent
could be changes in response to the same stimuli
could be changes in response to the multiple stimuli
Regulation
operon
basic mechanism for the control of gene expression in prokaryote
promoter
beginning of transcription of a gene by RNA polymerase
typically located directly upstram of the transcription initiation site
operon
transcribed from the same promoter
give a single mRNA carrying multiple coding sequences
operator
adjacent to the promoter of a bacterial operon
binds repressor/activator proteins
in response to controlling the rate of transcription of the operon
Negative/positive control system
tryptophan (trp) operon
regulation of enzyme activity
tryptophan present
repressor active
inhibt own production by activating the repressor protein
operon off
the tryptophan binds to the operator, blocking transcription
lac operon
lactose operon( inducible operon)
lactose present, glucose absent
E.Coli growth
on glucose and lactose
new enzymes are synthesized
isopropylthiogalactoside
no hydrolyzed by β-galactosidase
most commonly used in recombinant protein expression in E.Coli
eukaryote
transcription
histone binding
decrease the probability of RNA synthesis
histone modification
histone tails normally have positive charge
binding to negatively charged DNA on other nucleosomes
Acetylation cause his tone tails to lose positive charge
DNA methylation
DNA structure change
Decrease RNA synthesis probability
Methylation signals acetylation removal
Decrease RNA synthesis probability
Methylations can be inherited, causing epigenetic inheritance
post-transcriptional processing
5' cap and poly-A tail
Increase protein synthesis probability
Alternative splicing
May increase or decrease the protein synthesis probability
transcription initiation regulation
May increase or decrease the protein synthesis probability
post-transcriptional processing
cause RNA degradation
5' caps or poly-A tails not correct
miRNA
Decrease Protein synthesis probability
protein degradation
ubiquitination
Phosphoylated
Used to recruit the ubiquitous liase that adds ubiquitin
regulation of gene expression思维导图模板大纲
sugar metabolism in prokaryote思维导图模板大纲
cooperativity and allosteric effects思维导图模板大纲
allosteric activators ad inhibitors
transcript will be degraded思维导图模板大纲
Ways cell know what protein to degrade思维导图模板大纲
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