AP Bio - Ch.15: Regulation of Gene Expression

Operon Model

how Prokaryotes undergo gene regulation.

• promoter — where RNA polymerase binds

• operator — on/off switch for transcription

• related-transcription genes

feedback inhibition

Inhibiting the transcription of a product when there is enough product already → seen in repressible operons in prokaryotes

Repressible

_____ operons are turned ON produces end-product→ anabolic → turned off

eg. trp operons

co-repressor

what the product acts as in repressible operons → activates the repressor

Inducible

____ operons are turned OFF → catabolic → can be turned on to reduce accumulated end-product

eg. lac operons

inducer

what the product acts as in inducible operons → inactivates the repressor

Control elements

also known as enhancers, they’re non-coding segments of DNA where transcription factors attach.

How Eukaryotes undergo gene regulation alongside its chromatin structure

Acetylation

the loosening of the chromatin structure → promotes transcription in Eukaryotes

Methylation

the tightening of the chromatin structure → reduces transcription in Eukaryotes

• can be passed on to offspring → irreversible → epigenetic inheritance

ncRNAs

non-protein coding RNAs. Still play a crucial role in regulation gene expression (though not producing any proteins) via direct interference in the transcription process