Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Bio Exam II
Gene Regulation
| Term | Definition |
|---|---|
| lac operon model- the basics | - e. coli: normal stomach bacteria, adjusts based on host - humans drink milk= e. coli digests lactose |
| Induction | Turning on gene expression |
| inducer | compound that stimulates gene expression |
| inducible enzyme | -coded for by inducer gene - produced in response to inducer - contrast w/ constitutive enzymes |
| Operon | - complex in DNA: group of genes with related functions - regulatory DNA sequences - promoter: RNA poly. binding site not transcribed - operator: "switch" sequence for gene expression - 3 genes: lac z, lac y, lac a |
| Negative regulation of lac operon | - no lactose= operon off, no expressed - with lactose= operon expressed |
| Involves Repressor | repressor gene: codes for repressor protein, regulates gene expression - always on constitutive expression - not always part of operon |
| Lac Repressor Activity | - no lactose: repressor binds to operator - RNA poly. can bind promoter, can't transcribe genes |
| Lactose affects lac expression | - lactose enters cell, converted to allolactose - binds 2nd site on repressor protein - inactive by changing structure= cannot bind operator - allolactose is a non-competitive inhibitor of repressor protein |
| Allolactose in the inducer | - induces lac operon genes by inactivating the repressor protein - allows transcription to occur - results in low levels of lac expression |
| What is transcribed? | - 1 long mRNA w/ all 3 genes - each gene w/ own start & stop codon |
| NO NUCLEUS | transcription and translation happens simultaneously |
| Positive Control of Lac Operon | - positive control: regulation by an activator that binds DNA to stimulate transcription (high expression when active) - lactose can be used for E - glucose present= use first - lac operon expression responds to lactose & glucose levels |
| Lac Promoter Inefficient | - low affinity for RNA pol. - Solution: CAP- catabolic activator protein - increases affinity of promoter for RNA pol - CAP inactive alone - CAP active when bound to cAMPT: cyclic AMP (adenosine monophosphate) |
| Effects of CAP-cAMP | - low glucose= cAMP increases - CAP-cAMP binds; CAP binding site next to RNA pol. binding site - increases RNA pol. binding - bonds double helix - = positive control ( increases expression) |
| Lac Operon Activity:4 Structures | - high glucose/ no lactose= no CAP, repressed, no expression - no glucose/ high glucose= CAP, induced, high expression - no glucose/ no lactose= CAP, released, no expression - high glucose/ high lactose= no CAP, induced, low expression |
| Eukaryotic gene regulation | - eukaryotic cells respond to envi. - multicellular: allows for specialization & organization - achieved through differential gene expression |
| Regulation of Transcription Initiation | - more complex than prokaryotes - involves DNA sequences & transcription factors ( proteins that bind DNA) (promote or inhibit transcription initiation) |
| Post- transcriptional regulation | - length of poly-a-tail affects level of expression |
| Alternative Splicing | - different polypeptides from same gene |
| Post-Transcriptional Regulation | - polypeptides often processed= final protein - must be folded correctly - often chemical modifications |
Created by:
tennadeleta.
Popular Biology sets