16. Regulation of Expression

In eukaryotes, what allows only certain genes to be expressed in different types of cells?

Compare and contrast the items in each pair:

(c) general transcription factors and sigma.

Compare and contrast the items in each pair:

(a) enhancers and the E. coli CAP binding site

Compare and contrast the items in each pair:

(b) promoter-proximal elements and the operator of the lac operon

In the follow-up work to the experiment shown in Figure 19.6, the researchers used a technique that allowed them to see if two DNA sequences are in close physical proximity (association). They applied this method to examine how often an enhancer and the core promoter of the Hnf4a regulatory gene were near each other. A logical prediction is that compared with rats born to mothers fed a healthy diet, the Hnf4a gene in rats born to mothers fed a protein-poor diet would

a. Show no difference in how often the promoter and enhancer associated

b. Never show any promoter–enhancer association

c. Show a lower frequency of promoter–enhancer association

d. Show a higher frequency of promoter–enhancer association