Chapter 16: Control of Gene Expression

The presence or absence of tryptophan determines whether the genes that code for the necessary enzymes in tryptophan synthesis will even be transcribed. a.This is true b.This is false

A

When an effector molecule binds to a transcription repressor protein, the repressor protein changes shape and is no longer able to bind to DNA. What would happen to the rate of transcription if the concentration of the effector molecules was reduced? a.Increase b.Decrease c.Remain the same

A

An operon is a— a.cluster of genes that share a promoter and regulatory region b.mRNA that codes for multiple related proteins c.transcriptional inhibitor protein d.group of small effector proteins e.complex of rRNA and proteins that assembles polypeptides

A

How does the presence of lactose cause the lac operon to be transcribed? a.Lactose binds to the allosteric site on the repressor, inhibiting DNA binding by the repressor b.Lactose binds to the CAP site on the promoter region c.Lactose cannot be transported into the cell d.Lactose binds to the RNA polymerase e.Lactose binds to the allosteric site on the lactose permease

A

In addition to controlling transcription, eukaryotic cells can regulate gene expression by failing to unpack coiled DNA or influencing the speed with which mRNA is broken down prior to translation. a.This is True b.This is False

A

In bacteria, genes are typically turned on and off in direct response to short-term changes caused by environmental conditions. a.This is true b.This is false

A

Inducible operons are able to be switched on by the presence of effector molecules. These allow for efficient responses to changes in the cell's environment. a.This is true b.This is false

A

Regulatory proteins can block or initiate transcription when bound to promoters. a.This is true b.This is false

A

The most common way gene expression is regulated in both prokaryotes and eukaryotes is through the— a.Control of gene transcription b.Control of gene translation c.Prevention of DNA uncoiling d.Breakdown of proteins formed in translation e.None of the above

A

An enhancer— a.Is a factor necessary to assemble transcription apparatus and recruit RNA polymerase II b.Is a DNA sequence that is far from the gene but can promote its expression c.Can increase the level of transcription in certain cell types d.Splices out the intron sequences e.Is a regulatory site on DNA that prevents the initiation of transcription

B

Cyclic AMP (cAMP) is a small effector molecule that binds to CAP. When cAMP binds to CAP the transcription rate of the Lac-operon increases. Glucose inhibits cAMP production. How would the addition of glucose affect the rate of lactose metabolism? a.Increase b.Decrease c.Remain the same

B

What would be the action of an activator transcription factor? a.Inhibition of gene transcription b.Increase in the number of mRNAs transcribed c.Initiating ribosomal activity d.Activation of nucleases e.Promotion of nucleotide synthesis

B

GTFs (general transcription factors) are proteins that bind to DNA. What is their function? a.Blocking the formation of mediator proteins b.Suppression of transcription by binding to the TATA box c.Initiate transcription by forming an initiation complex d.Allosteric inhibition of RNA polymerase e.None of the above

C

How can a single RNA transcript lead to the translation of different proteins? a.The same RNA transcript may contain one of several different 5' untranslated regions b.The same RNA transcript may contain one of several different caps c.The same RNA transcript may be spliced in several different ways d.The same RNA transcript may contain one of several different promoters e.The same RNA transcript may contain one of several different 3' untranslated regions

C

If a mutation damaged the enhancer regulatory element in a eukaryotic gene promoter, how would this affect the transcription of the gene? a.The transcriptional start sight would be shifted b.The TATA box would be non-functional c.The rate of transcription would be very low d.The promoter would signal early termination e.Transcription would be inaccurate

C

When glucose is present, the levels of cyclic AMP in the cell are low. What occurs in the cell as a consequence of high glucose? a.Cyclic AMP levels are low so the lac operon genes are transcribed b.The cell converts glucose to lactose c.Cyclic AMP levels are low so CAP will not bind to the CAP binding site so the genes are not transcribed d.There is no effect

C

What is polycistronic mRNA? a.mRNA that is transcribed from multiple loci b.mRNA that leaves the cell to signal other cells c.mRNA that forms ribosomes d.mRNA that codes for multiple proteins e.mRNA that is double stranded

D

Which of the following would not be considered a mechanism used by eukaryotes to regulate gene expression? a.Tight packing DNA b.Regulation of transcription c.Regulation of breakdown of mRNA d.RNA interference e.Binding of tryptophan to a repressor protein

E