Lac Operon Flashcards
What is the function of the Lac Operon?
It regulates the expression of genes
The Lac Operon makes sure that
Only the proteins necessary are made
The Lac Operon makes sure that gene expression is
Regulated at transcription
The Lac Operon is found in
Bacterial E. Coli
Bacterial E. Coli uses what as its main energy source?
Glucose
What does Bacterial E. Coli use when glucose is not available?
Lactose
The Lac Operon has genes which
Will help E. Coli break down lactose
What are the three structural genes of the Lac Operon?
- Lac Z
- Lac Y
- Lac A
Lac Z is a gene which
Breaks lactose into Glucose + Galactose and codes for Beta Galacto
Lac Y is a gene which
Helps bring lactose into the cell and codes for Enzyme Lactose Permease
The operator site is found where?
After the promoter site
The operator site has which protein?
A repressor, which blocks RNA Pol by default
When does the conformation of a Repressor change?
After lactose binds
What happens to the repressor after the lactose binds?
The repressor falls off the operator site, allowing for the expression of the Lac Operon
Lactose is composed of
Glucose + Galactose
What is an Operon?
Unit of genomic DNA containing a cluster of genes which are controlled by a promoter
What is a promoter?
A single regulatory signal
Within the operon, a cluster of genes is transcribed into a
Single mRNA strand
What is the Lac Operon?
Inducible set of genes responsible for importing and breaking down lactose as a use of energy
What is the role of the Lactose in the Lac Operon?
It acts as an inducer, which induces the transcription of the Lac genes
Which structural genes are needed for lactose catabolism?
- Lac Z
- Lac Y
What is the function of the promoter of the Lac Operon?
It promotes transcriptional structural genes
What are two regulatory sequences which lie upstream of Lac Operon?
- Repressor Protein Genes
- Associated promoter for that repressor protein
The repressor protein is constitutively expressed when
Glucose is readily available to the cell
What does the repressor protein do on a regular basis?
It represses binding of RNA Pol whenever glucose is readily available
What happens when a regulatory protein binds to the lac operator?
It interferes with the operator and represses the binding of RNA Pol
What is the goal of the RNA Pol regarding the operon?
To bind with the lac operator in the promoter region
The binding of the regulatory protein allows for the
Prevention and repression of transcription of genes for lactose metabolism
What happens when lactose is available to the cell and not glucose?
Lactose passively enters the cell at a slow rate
What happens when the repressor falls off the operon?
RNA Pol is available to transcribe all 3 genes
Lactose permease allows for
More lactose to enter the cell
Beta Galact allows for the
Breaking down of lactose into galactose and glucose
What is the “Inducer Exclusion”?
A process in which the transport of glucose blocks the transport of lactose into the lac operon
The Lac Operon is the interaction between
The inducer and repressor molecules which mediate gene expression
The cell expands energy to
Make enzymes only when necessary
