Chapter 11: Regulation of Gene Expression

Question 1

What is gene expression?

Answer 1

Gene expression refers to the transcription and translation of a particular gene.

Question 2

What is the difference between constitutive, inducible, and repressible genes?

Answer 2

Constitutive genes are actively expressed all the time inside a cell(ex. proteins required for protein synthesis)

Inducible genes are normally off and are expressed only when their proteins are needed by the cell.

Repressible genes are normally on, but can be turned off when their products are not needed

Question 3

Genes can be regulated at th level of transcription. Transcription is initiated at the ______(1), a short stretch of DNA sequence that lies upstream of the transcription start site. _______________(2) must bind here to begin transcription.

Answer 3

(1) promoter
(2) RNA polymerase

Question 4

Transcriptional control can be negative or positive. What does positive and negative regulation involve?

Answer 4

Negative regulation involves repressor proteins that bind at or near the promoter and prevent RNA polymerase from binding to the promoter.

Positive regulation involves activator proteins that bind at or near the promoter to help facilitate or initiate transcription(often by helping RNA polymerase to stably bind to the promoter).

Question 5

The lac operon is an example of _________(1) expression in prokaryotes.

Answer 5

(1) inducible

Question 6

Describe the following difference in transcription in bacteria and eukaryotes:

1. Locations of functionally related genes
2. RNA polymerases
3. Promoters and other regulatory sequences
4. Imitation of transcription