Regulation of Gene Expression (Chapter 7)
Reading Guide
1. Why is it important for bacterial cells to be able to regulate gene expression? Provide
an example.
2. What is meant by the following:
constitutive enzymes
inducible enzymes
repressible enzymes
3. What is the role of repressor proteins and activator proteins in transcription? Where on
the DNA do they bind?
4. The lactose operon is a model of bacterial gene regulation. It consists of a collection of
genes which code for proteins that are necessary for the metabolism of lactose. Review
figure 7.19 in the text and then answer the following questions.
a. Under what conditions is the lactose operon “on”, meaning that the genes are
transcribed and translated.
b. Under what conditions is the lactose operon “off”?
c. If a cell is growing in a broth of glucose and lactose, which nutrient would be
metabolized first? Why? Which would be metabolized second? Why?
5. Provide an example of a situation in which an organism will alter gene expression.