chapter 18

Question 1

regulatory gene

Answer 1

gene from which the repressor is produced, located some distance from the operon it controls (regulates)

Question 2

repressor protein

Answer 2

protein that prevents gene transcription by binding to the operator and blocking RNA polymerase

Question 3

corepressor

Answer 3

molecule that cooperates with a repressor protein to switch a repressible operon off

Question 4

promoter

Answer 4

part of the DNA strand to which transcription factors and RNA polymerase bind

Question 5

operator

Answer 5

the part of the promoter that serves as the binding site for the repressor; the on/off switch of the operon

Question 6

gene of operon

Answer 6

the gene(s) whose expression is controlled by the operator

Question 7

Inducible operons

Answer 7

are usually off but can be turned on

Question 8

repressible operons

Answer 8

are usually on, but can be turned off

Question 9

What is differential gene expression?

Answer 9

the expression of different genes by cells with the same genome

Question 10

Why is differential gene expression important in multicellular eukaryotic organisms?

Answer 10

it leads to differences between cell types within the body

Question 11

What are control elements?

Answer 11

segments of noncoding DNA that serve as binding sites for transcription factors

Question 12

How do control elements influence gene expression?

Answer 12

they give the cell better control of gene expression by requiring additional steps for transcription

Question 13

What are cytoplasmic determinants?

Answer 13

substances in the egg that influence early development

Question 14

How do cytoplasmic determinants influence morphogenesis?

Answer 14

They are distributed unevenly in the unfertilized egg; As the zygote divides by mitosis, the daughter cells may contain different cytoplasmic determinants causing them to differentiate into separate cell types as well as giving shape and function