-
In bacteria, gene expression is influenced primarily by WHAT?
Environment
-
Constitutive means what?
The gene is always on
-
Inducible means what?
Means that the gene is normally off, but it can be turned-on in response to a specific signal from the environment.
-
Repressible means what?
Means that the gene is normally on, but it can be turned-off in response to a signal from the environment.
-
If there is not sufficient glucose it its environment, E. coli can metabolize WHAT instead of glucose?
Lactose
-
E.coli only expresses the genes for Lactose metabolizing enzymes (at high levels) when what?
- Glucose is not available &
- Lactose is present in the environment
-
What is an Operon?
In bacteria, a cluster of adjacent genes that share a common operator & promoter & are transcribed into a single mRNA. All the genes in an Operon are regulated coordinately; that is, all are transcribed or non are transcribed.
-
The structural genes that encode lactose metabolizing enzymes are organised into what?
An operon
-
What Lac gene encodes Beta-galactosidase?
lacZ
-
What does Beta-galactosidase do?
Breaks down lactose
-
What Lac gene encodes Permease?
lacY
-
What does Permease do?
Transports lactose into the cell
-
What are the Structural Genes of the lac Operon?
lacZ, lacY, lacA
-
What comprises the Regulatory region?
Promoter & Operator
-
Transcription of the structural genes is controlled by what?
A WEAK promoter and an operator
-
What are the cis-elements of the lac Operon?
Promoter & Operator
-
What does it mean to be a cis element?
It means that in order to function the genes must be on the same DNA as the structural genes.
-
What is located nearby, but not a part of the Operon?
The regulatory gene lacI
-
What does the lacI gene encode?
lac repressor
-
What is the trans element of the lac Operon?
lac Repressor
-
What does it mean to be a trans element?
This means that it functions just as well when lacI is on a different DNA molecule
-
Lactose metabolism in E. coli is regulated by what kind of system?
an Inducible System
-
The lactose genes are transcribed at a SIGNIFICANT level only when what is present?
Lactose
-
What is the inducer of the lac Operon?
Lactose
|
|