Biology

Robert J. Brooker

Chapter 14

Gene Expression at the Molecular Level III: Gene Regulation - all with Video Answers

Educators

Chapter Questions

Problem 1

Genes that are expressed at all times at relatively constant levels are known as ______ genes.
a. inducible
b. repressible
c. positive
d. constitutive
e. negative

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 2

Which of the following is not a level at which gene regulation occurs in bacteria?
a. transcription
b. RNA modification
c. translation
d. post-translation
e. All of the above are levels at which bacteria are able to regulate gene expression.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 3

Transcription factors that bind to DNA and stimulate transcription are
a. repressors.
b. small effector molecules.
c. activators.
d. promoters.
e. operators.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 4

In bacteria, the unit of DNA that contains multiple genes under the control of a single promoter is called _____ The mRNA produced from this unit is referred to as _____ $\mathrm{mRNA}.$
a. an operator, a polycistronic
b. a template, a protein-encoding
c. an operon, a polycistronic
d. an operon, a monocistronic
e. a template, a monocistronic

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 5

For the lac operon, what would be the expected effects of a mutation in the operator site that prevented the binding of the repressor protein?
a. The operon would always be turned on.
b. The operon would always be turned off.
c. The operon would always be turned on, except when glucose is present.
d. The operon would be turned on only in the presence of lactose.
e. The operon would be turned on only in the presence of lactose and the absence of glucose.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 6

The presence of ______ in a bacterium's environment prevents CAP from binding to the DNA, resulting in ______ in transcription of the $\operatorname{lac}$ operon.
a. lactose, an increase
b. glucose, an increase
c. cAMP, a decrease
d. glucose, a decrease
e. lactose, a decrease

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 7

The $t r p$ operon is considered _______ operon because the protein encoding genes necessary for tryptophan synthesis are not expressed when the level of tryptophan in the cell is high.
a. an inducible
b. a positive
c. a repressible
d. a negative
e. both $c$ and $d$

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 8

Regulatory elements that function to increase transcription levels in eukaryotes are called
a. promoters.
b. silencers.
c. enhancers.
d. transcriptional start sites.
e. activators.

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 9

The iron regulatory protein (IRP) binds to the iron regulatoty element (IRE) when iron levels are ______ and _______ translation of ferritin mRNA.
a. high, stimulates
b. high, inhibits
c. low, stimulates
d. low, inhibits
e. both a and d

Christina Sorrentino

Christina Sorrentino

Numerade Educator

Problem 10

_______ refers to the process that allows a single type of pre-mRNA to give rise to multiple types of mRNAs due to different patterns of intron and exon removal.
a. Spliceosomes
b. Variable expression
c. Alternative splicing
d. Polycistronic mRNA
e. Induced silencing

Christina Sorrentino

Christina Sorrentino

Numerade Educator