[Lec 8] Mastering Biology: Regulation of Eukaryotic Transcription

Question 1

Which statements about the modification of chromatin structure in eukaryotes are true?
Select all that apply.

a. Methylation of histone tails in chromatin can promote condensation of the chromatin.
b. DNA is not transcribed when chromatin is packaged tightly in a condensed form.
c. Acetylation of histone tails is a reversible process.
d. Some forms of chromatin modification can be passed on to future generations of cells.
e. Deacetylation of histone tails in chromatin loosens the association between nucleosomes and DNA.
f. Acetylation of histone tails in chromatin allows access to DNA for transcription.

Answer 1

a,b,c,d,f

Question 2

Which of the following protein domains would be most likely to recognize and bind to acetylated lysine residues on nucleosomes?

a. homeodomains
b. zinc fingers
c. chromodomains
d. bromodomains

Answer 2

d.

Question 3

Which of the following mechanisms illustrates a form of transcriptional repression that is unique to eukaryotes?

a. repressors recruiting enzymes to modify groups on histones to compact chromatin
b. repressors binding to a site near an activator binding site where they interact with and inhibit the activator
c. repressors recruiting enzymes to modify groups on histones to loosen chromatin
d. repressors blocking RNA polymerase by binding an operator site within the promoter

Answer 3

a.

Question 4

Which of the following best describes the mechanism by which steroid hormones control gene expression?

a. Steroid hormones enter a cell, bind directly to hormone response elements (HREs), and enhance transcription.
b. Chaperone proteins transport steroid hormones into the cell and guide them to their target genes.
d. Steroid hormones that enter the cell activate receptors. These hormone-receptor complexes then bind HREs and influence gene expression.
e. Steroid hormones transport mRNA from the nucleus into the cytoplasm, where it is translated into protein.

Answer 4

c.

Question 5

Which of the following best describes the role of chaperone proteins in the regulation of gene expression by steroid hormones?

a. Chaperone proteins enter the cell and bind receptor molecules.
b. Chaperone proteins directly enhance transcription.
c. Chaperone proteins maintain functionality of the receptor.
d. Chaperone proteins activate receptor proteins.

Answer 5

c.

Question 6

The reason some cells respond to the presence of a steroid hormone while others do not is that _______.

a. the receptors necessary for regulation differ among cells of various types
b. the specific HRE is present only in certain cells
only certain cells contain the gene that is targeted by a given steroid hormone
c. chaperone proteins block the hormone response elements (HREs) in some cells

Answer 6

a.