Deck 29: Regulation of Gene Expression

Question 1

In a histone protein, what modification to lysine marks the nucleosome as a transcription target?

A)phosphorylation
B)methylation
C)ubiquitylation
D)ADP-ribosylation
E)acetylation

Answer 1

E

Question 2

Which of the genes in the SOS regulon encodes a DNA polymerase?

A)recA
B)lexA
C)uvrA
D)uvrB
E)dinA

Answer 2

E

Question 3

Which of the following structural features of the trp leader sequence, trpL, explains why transcription of the full trp operon is prevented even when the repressor is not bound to the operon?

A)an A-rich region of the template strand acts as a factor-independent transcription terminator
B)there is a stop codon present as the 15^th codon of the trpL sequence
C)the ribosome is stalled at two adjacent Trp codons under conditions where Trp is low
D)a charged tRNA^Trp binds to one of the adjacent Trp codons to block ribosomal movement
E)none of the above

Answer 3

A

Question 4

Lysine methylation in a histone protein produces a form of chromatin known as ________ with the genes being transcriptionally __________.

A)euchromatin; active
B)euchromatin; inactive
C)heterochromatin; active
D)heterochromatin; inactive
E)none of the above

Question 5

Which of the following bacteriophage $\lambda$ proteins serves as both an activator and a repressor?

A)cI
B)cII
C)cIII
D)Cro
E)N

Question 6

The bromodomain of nucleosome remodeling complexes binds to ____________ histones while the chromodomain binds to ___________ histones.

A)acetylated; methylated
B)acetylated; phosphorylated
C)methylated; acetylated
D)methylated; phosphorylated
E)none of the above

Question 7

A short RNA that is complimentary to a specific mRNA and used for inhibition of translation is called ______________.

A)antisense RNA
B)missense RNA
C)nonsense RNA
D)senseless RNA
E)none of the above

Question 8

What is thought to occur when CRP binds to DNA?

A)formation of a hairpin that prevents progression of RNA polymerase
B)bending of DNA to facilitate RNA polymerase binding
C)blocking of promoter regions to prevent binding of RNA polymerase
D)forms non-covalent interactions with RNA polymerase to bind it to DNA
E)none of the above

Question 9

DNA methylation in eukaryotes plays a role in ____________.

A)methyl-directed mismatch repair
B)protection of restriction sites
C)chromatin remodeling
D)cancerous cell growth
E)gene silencing

Question 10

In prokaryotes, DNA methylation occurs on ______ while in eukaryotes, methylation occurs on _______.

A)adenine; thymine
B)adenine; cytosine
C)guanine; adenine
D)guanine; thymine
E)guanine; cytosine

Question 11

If both lactose and glucose are present in large amounts, which of the following scenarios would result?

A)lac repressor bound to promoter, CRP bound to promoter, no lac operon transcription
B)lac repressor bound to inducer, CRP bound to promoter, no lac operon transcription
C)lac repressor bound to inducer, CRP bound to promoter, lac operon transcribed
D)lac repressor bound to inducer, CRP not bound, no lac operon transcription
E)lac repressor bound to inducer, CRP not bound, lac operon transcribed

Question 12

Bacteriophage $\lambda$ establishment of lysogeny in E. coli cells requires a high concentration of _____. This is achieved by the ____ protein binding to the P_RE regulatory site.

A)Cro; cI
B)Cro; cII
C)Cro; cIII
D)cI; cII
E)cI; cIII

Question 13

Which of the following accounts for the greater complexity in eukaryotic transcriptional control when compared with prokaryotic control?

A)physical separation of transcription from translation
B)the presence of chromatin instead of naked DNA
C)the larger size of the chromosomes
D)the presence of introns
E)none of the above

Question 14

When bacteriophage $\lambda$ lysogeny terminates and lytic growth in E. coli cells begins, ____ is inactivated leading to unoccupied O_R sites. _____ is produced, ultimately resulting in DNA replication.

A)Cro; cI
B)cI; Cro
C)cII; Cro
D)cI; cII
E)none of the above

Question 15

At the transcriptional level, how does tryptophan control the production of genes within the trp operon?

A)the trp repressor contains a high percentage of Trp residues and is thus only produced when Trp levels are high
B)without sufficient Trp, the production of the trp repressor is truncated, thus producing a protein that cannot bind to the operon, ultimately resulting in structural gene expression
C)high levels of Trp cause the repressor to be proteolytically digested
D)the trp repressor binds to the operon only when bound to Trp
E)none of the above

Question 16

DNA damage that requires RecA to bind to a DNA gap activates proteolysis of _____, which then activates the transcription of genes within the SOS regulon.

A)cI
B)Cro
C)LexA
D)uvrA
E)uvrB

Question 17

What elements are contained within the promoter of the lactose operon?

A)operator and CRP site
B)operator and repressor
C)CRP site and repressor
D)operator, CRP site and repressor
E)none of the above

Question 18

Which of the following is the true inducer that binds to the lac repressor in vivo?

A)lactose
B)glucose
C)galactose
D)isopropyl- $\beta$ -thiogalactoside
E)allolactose

Question 19

On the polycistronic mRNA of bacteriophage MS2, the ability to translate multiple copies of the coat protein but only a single copy of the A protein is accomplished by _________.

A)regulatory RNA molecules
B)translational repression by protein binding to mRNA
C)antisense RNA
D)ribosome binding site occlusion
E)none of the above

Question 20

The phosphorylation of several RNA polymerase II serine residues has been identified as a key event in eukaryotic translation initiation. Which of the following is one of the enzymes responsible for this phosphorylation?

A)Mediator complex
B)Rap1
C)TFIIH
D)TATA box-binding protein
E)ACT

Question 21

Give the sequence and draw the first two residues of a morpholino oligo that would serve as an antisense RNA for the following mRNA sequence (you may use the letter A, C, G and U to denote the bases):
5'-CAUGUCC-3'

Question 22

An mRNA whose translation is controlled by binding of a metabolic end product such as flavin adenine dinucleotide or adenosylcobalamin is called a____________.

A)ribozyme
B)miRNA
C)riboswitch
D)regulatory RNA
E)none of the above

Question 23

Design an antisense RNA that prevents the start of translation for any mRNA in an E. coli cell.

Question 24

If an miRNA is completely complementary to an mRNA, what is the result of the pairing of these two molecules?

A)rapid translation of the mRNA
B)repeated translation as the miRNA prevents destruction of the mRNA
C)slowed translation of the mRNA
D)degradation of the mRNA
E)none of the above

Question 25

Show how glutamine interacts with an A-T base pair as seen in the cI and Cro repressors.