Ch. 16 Control of Gene Expression

Increasing the frequency of initiation occurs through positive control. The regulatory proteins responsible are__________________. Promoters Operators Repressors Activators Effectors

Activators

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

B. Control of gene transcription

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. Is a DNA sequence that is far from the gene but can promote its expression

Which of the following would not be considered a mechanism used by eukaryotes to regulate gene expression? Tight packing DNA Regulation of transcription Regulation of breakdown of mRNA RNA interference Binding of lactose to the CAP protein

Binding of lactose to the CAP protein

In the lactose operon of bacteria, the structural genes are not transcribed unless lactose is present. Which of the following describes repression under these conditions (no lactose present=no transcription)? Repressor molecules are bound to a section of DNA termed the promoter Repressor molecules are bound to molecules called inducers Repressor molecules are bound to a section of DNA termed the operator Repressor molecules are bound to structural genes

C. Repressor molecules are bound to a section of DNA termed the operator

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.Cyclic AMP levels are low so CAP will not bind to the CAP binding site so the genes are not transcribed

Regulatory proteins interact with the DNA by: A. Unwinding the DNA helix and changing the pattern of base pairing. B. Binding to the sugar-phosphate backbone of the double helix. C. Unwinding the helix and disrupting base-pairing. D. Binding to the major groove of the double helix and interacting with base-pairs.

D. Binding to the major groove of the double helix and interacting with base-pairs.

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

Lactose binds to the allosteric site on the repressor, inhibiting DNA binding by the repressor

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

The same RNA transcript may be spliced in several different ways

1. 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. This is True This is False

This is True

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

This is true

Regulatory proteins can block or initiate transcription when bonded to promoters. This is true This is false

This is true

Which enzyme is used to help mark proteins for destruction? proteases proteasome Ubiquitin Ubiquitin ligase methylation

Ubiquitin ligase

This type of RNA prevents translation by binding directly to mRNAs. tiRNA tRNA rRNA miRNA None of the above

tiRNA