Gene Regulation by Bacteria and Eukaryotes Flashcards
What are the two main ways in which bacteria regulates its gene expression
It can regulate its gene regulation by controlling the activity of the enzyme that produces product, or by turning off or on the gene that expresses the enzyme
How does bacteria control gene expression
Operon:P.O.G
The Operon is a cluster of different components that contribute to gene expression.
Promoter: is the location where RNA polymerase binds to DNA
Operator: controls the turning off or on the operon
Gene: structural genes that are expressed when the operon is turned on.
What controls the operator?
The presence of a repressor binded to the operator turns off the operon. This prevents RNA polymerase from binding to the promoter
What are the different types of Operons
There is the repressible and inducible operon
Repressible Operons
they are naturally always on, the repressor is not binded to the operator. The product that is catalyzed by the enzymes transcribed TURN OFF the operon by binding to the repressor
What is an example of an repressible operon
the trp operon.
What is the regulatory gene and where is it located
The regulatory operon encodes the gene for the repressor protein (regulatory protein), and it is located near the operon it is meant to control
What is the inducible operon
The inducible operon is usually turned off, it is not a primary need of the cell, used only during states of emergency. The inducible operon is turned off when an inducer binds to the repressor that is binding to the operator. This removes the repressor off the operator allowing transcription to occur.
What is meant by negative control of gene expression
Negative control is when a repressor is used to turn OFF the operon
What is meant by positive control of gene expression
Positive control means that the regulatory protein is purposed to promote gene expression not hinder it
Examples of positive control of gene expression
cAMP and CAP complex. cAMP binds to CAP which binds upstream to promoter–> RNA polymerase binds to promoter—> transcription increases
How does negative and positive control work in lac operons
LAC operons are naturally off, due to the repressor that binds to the operator. When there is a low glucose concentration and a high lactose concentration. The allocatose(inducer) binds to the repressor and removes it from the operator. This turns on the lac operon. The caMP and CAP complex increases the transcription rate.
