Genetics Prokaryotic Regulation

Negative Regulation

The default state of transcription is "on" unless a repressor turns it "off"

Positive Regulation

The default state of transcription is "off" unless a repressor turns it "on"

Repressible Transcription

Genes are turned off in response to specific signals

Attenuation

the use of translation to regulate transcription (prominent in tryptophan & has 2 conformation)

Attenuation (high concentration)

Ribosome reaches region 2 & causes termination in regions 3&4

Attenuation (Low concentration)

Ribosome stays at region 1 & transcription isn't terminated in regions 3 & 4

Inducible transcription

Genes are turned on in response to specific signals

Autoregulation

regulation where the gene controls its own expression. Can be either positive or negative regulation and might involve a co-repressor

Lac Operon

A system of regulation that allows for transcription in prokaryotes with allolactose as the inducer.

Riboswitches

RNA elements that respond by changing conformation in response to small molecule binding (affects transcription and translation)

Off

The semi-production of mRNA even in unfavorable conditions

aporepressor

A repressor that activates and binds to the operator in response to the binding of a substrate.

SAM

A compound involved in Met and Cys synthesis. Prominent in Riboswitches

Termination Loop

a loop formed in mRNA in the presence of tryptophan that ceases transcription of the trp operon (Knocks the RNA polymerase off the DNA molecule... Ending the transcription)

Riboswitches (high concentration)

AAT Loop & T loop in the presence of SAM

Riboswitches (low concentration)

AT loop in the absence of SAM

S-box

When SAM is bound to a compound, this riboswitch leads the formation of termination structure & stops transcription