BIO230H1 Lecture Notes - Lecture 3: Intron, Prokaryote

1.) What type of control best describes the lac operon when it is regulated by allolactose? Explain the features of this type of regulation using the lac operon as an example.

2.) What is positive gene regulation?

a) when an activator protein binds to the operator of a gene to turn expression off

b) when a repressor protein binds to the operator of a gene to turn expression off

c) when an activator protein binds to the operator of a gene to turn expression on

d) when a repressor protein binds to the operator of a gene to turn expression on

e) when a protein binds to DNA to change gene expression

3.) In the lactose operon of E. coli, what is the function of each of the following genes or sites: a) regulator, b) operator, c) promoter, d) structural gene Z and e) structural gene Y?

a) regulator gene

b) operator

c) promoter

d) structural gene Z

e) structural gene Y

4.) In a negative, repressible regulatory mechanism, transcription of the structural gene(s) occurs in

a) the presence of the co-repressor, but not in its absence.

b) the absence of the co-repressor, but not in its presence.

c) the presence of the inducer, but not in its absence.

d) the absence of the inducer but not in its presence.

e) the absence or presence of the co-repressor.

What are answers and can you explain them to me?

1. What is the term when the product of a biochemical pathway inhibits the activity of the first enzyme of a pathway?

2. Through control of gene expression, prokaryotes respond to changing __________ conditions.

3. A protein that negatively regulates transcription by binding to the operator is known as the

4. During attenutation, when tryptophan levels are high, the ________ stem-loop forms and transcription ________ the trpL gene.

5. The process of turning on the expression of a gene in response to a substance in the environment is called:

6. What is a function of some specific transcription factors?

7. How does exposing an E.coli cell to glucose affect the regulation of the lac operon via CAP?

8. The lac repressor protein works when mutations in the repressor gene and structural genes are: