Regulation of gene expression Flashcards
Cell types in a multicellular organism become different from one another because of which of the following?
A. They alter the sequence of their DNA to develop into different cell lines.
B. Large blocks of DNA are lost during vertebrate development.
C. They synthesize and accumulate
different sets of RNA and protein molecules.
D. None of the above is true.
C
In E. coli, the inability of the trp repressor to bind the promoter site would result in which of the following?
A. No substantial synthesis of the gene product
B. Inducible synthesis of the gene product
C. Decrease in tryptophan in the growth medium
D. Death of the E. coli culture
B
Which of the following mechanisms of gene regulation is considered an epigenetic mechanism?
A. Ubiquitylation of polypeptides
B. Interaction of leucine zippers with DNA segments
C. Methylation of DNA
D. Rearrangement of DNA
C
The different patterns of expression of the apolipoprotein B gene in the liver and intestine are due to the substitution of the C U in CAA codon. As a result, two different protein isoforms are produced by the two organs. Which type of gene regulation is this an example of?
A. RNA editing
B. Post-translational cleavage from precursor proteins
C. Epigenetic control
D. Transcriptional control
A
In the example of the apolipoprotein B gene, the substitution of C by U in CAA codon would result in
which of the following?
A. A longer polypeptide
B. A polypeptide of the same length with different amino acid sequence
C. A shorter polypeptide
D. No effect
C
The HIV virus is a retrovirus that is able to bypass the strict regulation of gene expression by bypassing which of the following levels of control?
A. Transcriptional control
B. Post-transcriptional control
C. Epigenetic control
D. RNA transport control
C
Proteins of the hsp family (heat-shock protein) have been found to facilitate accurate folding of polypeptides as they are being synthesized. If these molecular chaperones were to cease functioning, which of the following would likely occur?
A. Correct folding of polypeptides would continue at the same rate
B. Increase in activity of proteasome
C. Decrease in protein aggregates
D. All of the above
B
Which of the following is NOT a characteristic of a cis-acting element?
A. It is found on the same strand as the gene which it controls.
B. It is a polypeptide expressed from a distant gene.
C. It may act as a promoter or repressor.
D. All of the above are correct.
B
Each individual has an immune system that is unique from those of his parents and siblings. Which type of gene regulation is mainly responsible for this?
A. DNA rearrangement
B. Gene amplification
C. RNA editing
D. Alternative splicing
A
The primary action of steroid hormones is at which level?
A. RNA export from the nucleus
B. mRNA degradation
C. Gene rearrangement
D. Transcription
D
If the CpG segment just proximal to a tumor suppressor gene is amplified 100-fold. which of the following would most likely happen?
A. Increase acetylation of the segment
B. Increase protection against tumorigenesis
C. Deactivation of MeCP2 protein
D. Increase likelihood of developing a tumor
D
Peptide hormones affect geneexpression by binding to surface receptors. This produces second messengers such as cAMP, which with CREB, can bind to response elements of DNA. This is an example of what type of regulation?
A. Epigenetic control B. Transcriptional control C. RNA transport control D. Post-transcriptional control E. Translational control
B
Gene X44 is DNA segment encoding a protein that is low in concentration inside cells. Which of the following would the cell do to increase the concentration of the protein?
A. Increase transcription factors that bind to its silencer region
B. Increase transcription factors that bind to its promoter region
C. Activate its enhancer
D. All of the above
E. B and C only
E
Which of the following trans-acting factors has a DNA-binding domain that forms a dimer with the helix like a peg by inserting into the major groove?
a. Helix-turn-helix
b. Helix-loop-helix
c. Leucine zipper
d. Zinc finger
c
Aside from DNA rearrangement, what other level of gene regulation used in the form of 1 gene which results from alternative splicing and adenylation sites?
a. Transcriptional
b. post-transciptional
c. translational
d. post-translational
b
