Question 1

Which of the following acts as a corepressor to block transcription of the trp operon?

Accepted Answer

A)  cAMP 
B)  Lactose 
C)  Methionine 
D)  Tryptophan 
E)  CRP

Question 2

Which change would lead to a decrease in the expression of a gene?

Accepted Answer

A)  More expression of an activator of the gene 
B)  More expression of an activator of a repressor of the gene 
C)  Less expression of a repressor of the gene 
D)  Less expression of an activator of a repressor for the gene 
E)  More expression of an activator of an activator for the gene

Question 3

Which enzyme is involved in epigenetic changes?

Accepted Answer

A)  DNA ligase 
B)  Maintenance methylase 
C)  Histone deacetylase 
D)  Maintenance deacetylase 
E)  DNA prophase

Question 4

Suppose that a certain enzyme is synthesized whenever the solution in which the cells are growing contains substance Y.When substance Y is not present,the enzyme is produced only under certain environmental conditions.This phenomenon would most likely be an example of _______ gene regulation.

Accepted Answer

A)  positive 
B)  inducible 
C)  repressible 
D)  negative 
E)  positive-negative

Question 5

Suppose that the hypothetical protein Hrt87 interferes with the ability of kjh6 mRNA (also hypothetical)to attach to the ribosome.One would conclude,therefore,that Hrt87 is a(n)

Accepted Answer

A)  transcription factor. 
B)  transcription repressor. 
C)  operon. 
D)  sigma factor. 
E)  translational repressor.

Question 6

CREB is a transcription factor that regulates gene expression.It binds to DNA and activates promoters of genes involved in addictive behaviors.Researchers who compared CREB levels in the brains of a strain of rats called P rats and wild-type rats found that when P rats consumed alcohol,

Accepted Answer

A)  the total levels of CREB increased. 
B)  the total levels of CREB decreased. 
C)  the total levels of CREB remained the same. 
D)  levels of phosphorylated CREB increased. 
E)  levels of phosphorylated CREB decreased.

Question 7

Which statement about epigenetics is false?

Accepted Answer

A)  One type of epigenetic change occurs via DNA methylation. 
B)  One type of epigenetic change occurs via chromosomal protein alterations. 
C)  Epigenetic changes can lead to gene expression changes. 
D)  Epigenetic changes do not change the DNA sequence. 
E)  Epigenetic changes cannot be inherited.

Question 8

Which statement about microRNAs is false?

Accepted Answer

A)  They inhibit the translation of specific mRNAs by causing their premature degradation. 
B)  They are small (less than 30 nucleotides in length). 
C)  Any particular microRNA can regulate the expression of many target genes. 
D)  They are transcribed. 
E)  They serve an important function in alternate splicing.

Question 9

Which statement about virions is true?

Accepted Answer

A)  They are produced only in the lysogenic phase. 
B)  They are produced only in the lytic phase. 
C)  They are the host genes shut down by the virus. 
D)  They are produced in the lysogenic and lytic phases. 
E)  They are short,unused pieces of RNA in the viral genome.

Question 10

If a mutation causes a decrease in the activity of histone acetyltransferases,histones will most likely have a _______ affinity for DNA,and there will be _______ in transcription rates.

Accepted Answer

A)  greater;an increase 
B)  greater;a decrease 
C)  reduced;an increase 
D)  reduced;no change 
E)  reduced;a decrease

Question 11

If an HIV lineage obtains a mutation that causes its Tat protein to be somewhat less able to bind to RNA,the most likely result will be

Accepted Answer

A)  more initiation of transcription. 
B)  less initiation of transcription. 
C)  the termination of more partial transcripts,and thus the making of fewer complete transcripts. 
D)  the termination of fewer partial transcripts,and thus the making of more complete transcripts. 
E)  a reduction in the stability of complete transcripts.

Question 12

TFIID is

Accepted Answer

A)  a promoter. 
B)  an enzyme. 
C)  part of the TATA box. 
D)  a promoter and a transcription factor. 
E)  a protein and a transcription factor.

Question 13

Suppose that in gene HY6 there is little correlation between the amount of its mRNA and the amount of protein it produces.Which regulatory mechanism would explain the lack of correlation?

Accepted Answer

A)  Transcription factor 
B)  MicroRNA 
C)  Translation promoters 
D)  Modification of the ribosomes 
E)  Modification of the 5' cap

Question 14

If each interphase nucleus in a preparation of normal rat epithelial cells is found to contain a single Barr body,one can conclude that

Accepted Answer

A)  the cells are in meiotic prophase. 
B)  all of the chromatin in these cells is inactive. 
C)  the DNA in these cells has replicated itself. 
D)  the cells are not transcribing any genes. 
E)  the cells came from a female rat.

Question 15

Recent studies of monozygotic twins have revealed that

Accepted Answer

A)  methylation patterns become more similar over time. 
B)  methylation patterns become less similar over time. 
C)  the environment does not have a large influence on the epigenome. 
D)  methylation patterns do not change over time. 
E)  methylation patterns have no effect on gene expression.

Question 16

If a virus is in the lysogenic phase,it will

Accepted Answer

A)  integrate its DNA into the host cell chromosome. 
B)  excise its DNA from the host cell chromosome. 
C)  lyse or cut open the host cell. 
D)  induce point mutations in the host cell. 
E)  activate the host cell DNA.

Question 17

Alternative splicing helps to explain

Accepted Answer

A)  the small number of genes in the human genome. 
B)  why there are more mRNAs than there are human genes. 
C)  the great variety in proteins. 
D)  why different proteins can be made from the same genes. 
E)  All of the above

Question 18

The expression of the gene that encodes cyclin A varies considerably across the cell cycle,reaching a peak at the G2 phase.No other gene is similarly expressed.Based on this information,one can conclude that cyclin A is

Accepted Answer

A)  a transcription factor. 
B)  encoded by a constitutive gene. 
C)  encoded by an inducible gene. 
D)  part of an operon. 
E)  part of a replicon.

Question 19

What is the primary mechanism (or timing)involved in the shutdown of the host gene expression that occurs in bacteria infected by phage T4?

Accepted Answer

A)  The host genes are turned off because the phage encodes repressors shutting off the host genes. 
B)  The host genes are turned off because the phage polymerase competes with the host polymerase. 
C)  The host genes are turned off because the phage interferes with activators required for production of host genes. 
D)  The shutdown of host gene expression occurs after transcription. 
E)  The shutdown of host gene expression occurs after translation.

Question 20

Based on the effects of lin-4 and lin-14 mutations in C.elegans,worms in which there is an overexpression of the lin-14 gene would

Accepted Answer

A)  keep repeating the first larval stage. 
B)  skip the first larval stage and move right onto the second. 
C)  methylate DNA inappropriately. 
D)  fail to methylate DNA when appropriate. 
E)  overexpress CREB.

Exam 11: Regulation of Gene Expression