Deck 14: Control of Gene Expression

Question 1

Regulatory proteins can identify specific sequences on the DNA double helix without unwinding the helix. This is accomplished by inserting

A) RNA promoters into either the major groove or the minor groove of the double helix where the edges of the nitrogen bases protrude.
B) DNA-binding motifs into the minor groove of the double helix where the edges of the nitrogen bases protrude.
C) DNA polymerase into the major groove of the double helix where the edges of the nitrogen bases protrude.
D) RNA polymerase into the major groove of the double helix where the edges of the nitrogen bases protrude.
E) DNA-binding motifs into the major groove of the double helix where the edges of the nitrogen bases protrude.

Answer 1

DNA-binding motifs into the major groove of the double helix where the edges of the nitrogen bases protrude.

Question 2

You are studying regulation of a prokaryotic operon. Experimental results show that expression of the operon is increased when product levels are low. Based on this information, you conclude that the likely mode of regulation is

A) the operon is ON in the absence of its regulatory protein.
B) the operon is OFF in the absence of its regulatory protein.
C) the presence of an inducer will always cause a repressor to bind the operator.
D) the presence of an inducer will always prevent a repressor from binding the operator.

Answer 2

the operon is OFF in the absence of its regulatory protein.

Question 3

Your research project involves the characterization of a recently identified transcription factor. As part of your project, you want to determine if this transcription factor binds directly to any of the general transcription factors. Unfortunately, however, you are having trouble expressing and purifying the full length protein. An option that may help you achieve your research goal would be to

A) abandon this experiment and try a vastly different approach to your question, since transcription domains cannot be separated.
B) express large amounts of the general transcription factors.
C) express and purify only the DNA-binding domain, since transcription domains can be separated.
D) try to express and purify only the activation domain, since transcription domains can be separated.

Answer 3

try to express and purify only the activation domain, since transcription domains can be separated.

Question 4

You are studying the function of a recently identified gene in C. elegans. You perform genetic screens for several months in an attempt to isolate loss-of-function gene mutations, but your efforts are unsuccessful. Your advisor suggests you try another approach to eliminate gene function. The best technique to accomplish this goal would be

A) to design a repressor to bind to the operon of this gene.
B) use a histone deacetylase to induce a transcriptionally inactive state.
C) use a C. elegans strain with a homozygous TFIID mutation to prevent the translation initiation complex from forming.
D) use RNA interference to prevent mRNA translation.

Question 5

What is the difference between a gene that is derepressed and one that is induced?

A) A gene that is derepressed is turned on because a repressor molecule is absent. By comparison, a gene that is induced is turned on because an inducer molecule is present.
B) Genes that are derepressed are turned on because an inducer molecule is present. By comparison, a gene that is induced is turned on because a repressor molecule is absent.
C) There is no functional difference between a gene that is derepressed and one that is induced.
D) A derepressed gene is turned off and an induced gene is activated to be expressed.

Question 6

You have discovered a way to damage proteins associated with initiating over-active inflammatory responses. You must now begin a study on the pathway that follows the clean up of those damaged proteins. Where would your study be focused?

A) Attachment of ubiquitin to the protein, which would lead to transport of the protein to the lysosome that would engulf the protein and degrade it with lysozymes.
B) Tagging of the protein with ubiquitin and then proteolysis of the protein by proteases in the proteasomes.
C) Tagging of the protein with oligosaccharides first, which would then lead into the transport of the protein to proteasomes for proteolysis via proteases.
D) Oligonucleotides would attach to the protein and transport it to the lysosomes for digestion and recycling into products for energy formation.

Question 7

You are studying the affects of transcription factors on the activation of gene expression. However, when first starting your study you notice that some of the transcription factors bind further away from the DNA that it is aiming to transcribe. What description best explains this?

A) The transcription factor transcribes small RNAs that then bind to the promoter and activate the gene's expression.
B) Signals originate via inducers from the transcription factor to the site of promotion that activate transcription of the gene.
C) DNA looping transports the transcription factor closer to the promoter and initiates gene transcription.
D) The assistance of RNA looping moves the transcription factor closer to the promoter.

Question 8

Differentiated human cells may be distinguished from one another by

A) their genomes
B) the genes they express
C) their shape and function
D) their shape, function, and the genes they express
E) their shape, function, genome, and genes they express

Question 9

Nucleases are enzymes that degrade mRNA. In order for nuclease to overcome the inherent protections in mRNA that prevent its degradation nucleases must use

A) 5' decapping enzymes.
B) A and U sites that promote removal of the poly A tails.
C) C and G recognition sites that activate removal of poly A tails.
D) 3' end recognition sites that initiate quick degradation.
E) 3' cap and poly A tail sites that activate degradation.

Question 10

When stimulating formation of heterochromatin during RNA silencing in plants, the key changes that would be observed include Check all that apply

A) tightening of chromatin via methylated histones.
B) reduction in expression of methyl groups.
C) increasing histone methylation.
D) restricted access to histones via chromatin methylation.
E) the RNAi pathway enhances methylation.

Question 11

A gene is coded for only one protein and associated with only one specific tissue type. Is this statement correct and why?

A) No, some genes can be go through alternative splicing leading to the production of different proteins in different tissues.
B) Yes, all genes only code for one protein normally specific to one tissue type.
C) Yes, all tissue-specific proteins are only expressed from a single gene for that specific tissue.
D) No, all genes can encode more than one protein in multiple tissue types due to exon splicing formation.