Transcriptional (vs. Posttranscriptional) Regulation

Only the regulation of transcription

Depends on how much of a PROTEIN is in the cell

Posttranscriptional regulation regulates the mRNA half-life, translation, and degradation of the protein

Multiple genes made as ONE mRNA from a SINGLE control region (promoter)

One mRNA from the same promoter to make different proteins

Only in prokaryotes because they can start translocation before transcription ends

Where the repressor protein binds to a binding site called the "operator" which is downstream of the promoter.

The repressor protein binding prevents mRNA synthesis.

Binding site where the repressor protein binds downstream of the promoter as a way of negative control

Blocks RNA pol to prevent transcription

Negative Control

Protein that binds to the operator binding site downstream of the promoter to prevent mRNA synthesis and creates negative control

Binds downstream of the promoter

Activator Protein

Binds upstream of the promoter

Enhances RNA pol binding to enhance transcription

Used for positive control

Binds to activating site

A small molecule or environmental signal that turns on an inducible gene

Can work with positive or negative control

Repressible

Allows the bacterium to respond to the environmental presence of lactose and glucose

When a bacterium has a lac operon that allows it to respond to the presence of lactose and glucose however there is no lactose present

So the lac operon is turned off by the repressor protein blocking transcription unless lactose (inducer) is available in the environment to use

Activator

Activator protein that allows for the transcription of the mRNA for lactose breakdown when it binds to the inducer cAMP

Inducer

Binds to catabolite activator protein to activate transcription for the production of mRNA for breakdown of lactose

Activator protein enhances transcription in the presence of cAMP (inducer)

cAMP increases if glucose decreases

cAMP decreases if glucose increases

Cells use this to reduce transcription of the lac operon in the presence of glucose (cAMP inducer not present)

1) Sensor Kinase

2) Response Regulator

Senses the environment

Its shape gets changed by getting phosphorylated

It then transfers its phosphate to the response regualtor

Usually an activator protein that regulates the cell's response to the environment

When it gets phosphorylated by the sensor kinase it turns on transcription of the gene because the cell needs to respond to the environment

Sence the presence and number of bacteria around them by by secreting quorumone (HSL)

The more bacteria in the environment, the more HSL present

HSL binds to the bacteria and activates response regualtors to produce genes that allow them to compete with the other bacteria

Triggers the two component regulartory system

Neisseria pili variation

Resistant to antibiotics because they can switch their promoters and take on a "new identity" to survive in different environments