Unit 2 Ch. 14 HW

27) How could an activator influence gene expression at a promoter far away from the place that it binds DNA?

A Mediator protein is stimulated by the bound activator, and then the Mediator stimulates transcription.

30) Which of the following statements about enhancers is TRUE?

Enhancers are sequences to which activators bind.

17) Select the BEST description of the complexity of eukaryotic gene expression as compared to prokaryotic gene expression.

Eukaryotic transcription is usually influenced by many transcription factors while prokaryotic transcription is usually influenced by only a few transcription factors.

1) The cell is capable of regulating gene expression in a variety of situations and environments. Valid reasons for a cell to regulate gene expression include its ability to: c. keep a gene product available under all conditions.

False

1) The cell is capable of regulating gene expression in a variety of situations and environments. Valid reasons for a cell to regulate gene expression include its ability to: f. synthesize mRNA for every gene in the genome at all times.

False

15) Why does the concentration of glucose have an effect on the transcription of the lac operon?

Glucose is the preferred sugar for the bacteria. If it is present, lactose metabolism is suppressed.

35) How is it possible for a single gene to encode more than one polypeptide?

Introns can be removed from pre-mRNA in different combinations.

10) How does the cell recognize that lactose needs to be metabolized?

Lactose is converted into allolactose, which inhibits the lac repressor.

2) Export of an mRNA to the cytoplasm is blocked

Post-Transcriptional

2) Stability of an mRNA is regulated

Post-Transcriptional

2) The correct removal of introns of a pre-mRNA is prevented

Post-Transcriptional

2) A phosphate group is added to a protein making it inactive

Post-Translational

2) The rate of degradation of a protein is increased

Post-Translational

18) Transcription is carried out by the enzyme

RNA polymerase.

4) What is the MOST important reason a cell exhibits tight transcriptional control over the regulation of gene expression?

Regulation at the transcriptional level is energetically efficient for the cell.

28) Assembly of basal transcription factors begins at the ________ sequence in the promoter.

TATA

32) Which of the statements is the best explanation for why eukaryotes use so many regulatory elements, such as activators, repressors, coactivators, and basal transcription factors?

The complexity allows specific control over the timing and quantity of the protein produced.

33) Which of the following statements best describes the consequence of a mutated activator on expression of a transcriptional target gene?

The gene will be expressed, but in less than optimal quantities.

8) If lacI were mutated such that the lac repressor could no longer bind DNA, what effect would this have on the regulation of the lac operon?

The repressor protein would not function properly, and the lac operon would be over expressed.

9) If lacO were mutated, what effect would this have on lactose metabolism?

The repressor would not properly bind to the operator, and the lac operon would be over expressed.

19) Which of the following statement(s) about basal transcription factors is(are) TRUE?

They are essential for transcription and they cannot increase the rate of transcription by themselves.

21) Which statement represents the best explanation for why eukaryotes use basal, or general, transcription factors?

They give the cell tight control over transcription.

2) A repressor binds near a promoter

Transcriptional

2) An activator binds to an enhancer

Transcriptional

2) The 5' end of an mRNA forms a shape that blocks translation.

Translational

2) The ability of an mRNA to bind to ribosomes is changed

Translational

1) The cell is capable of regulating gene expression in a variety of situations and environments. Valid reasons for a cell to regulate gene expression include its ability to: a. make additional cells of the same type in response to a demand.

True

1) The cell is capable of regulating gene expression in a variety of situations and environments. Valid reasons for a cell to regulate gene expression include its ability to: b. synthesize enzymes to metabolize a particular nutrient

True

1) The cell is capable of regulating gene expression in a variety of situations and environments. Valid reasons for a cell to regulate gene expression include its ability to: d. execute a specific program of development (e.g. to become a blood cell or immune cell).

True

1) The cell is capable of regulating gene expression in a variety of situations and environments. Valid reasons for a cell to regulate gene expression include its ability to: e. stop synthesis of a cellular component when there is enough available in the cell.

True

14) How does glucose effect the lac operon?

When glucose levels are low, it stimulates the production of cAMP, which binds to and activates the CAP protein, allowing it to bind to the DNA.

13) In the absence of lactose, the lac repressor is

active and can bind to the operator.

7) The lac repressor is inactivated by binding to which of the following?

allolactose

26) A regulatory element that can function from a large distance (e.g. tens of thousands of base pairs) from a promoter is called

an enhancer.

36) Small RNAs, typically 22 nucleotides long, that function in post-transcriptional regulation of gene activity are produced

by digestion of double-stranded RNA into smaller pieces.

12) When in a complex with ________, the CAP protein binds to the CAP site and ________ the expression of the lac operon.

cAMP; switches on

34) DNA is associated with proteins to form ____________ .

chromatin

34) Removal of acetyl groups from histones results in a/an ____________ in gene expression.

decrease

11) The lac operon is expressed when

glucose is low and lactose is present.

34) An activator can increase transcription by attracting a ____________ to the region.

histone acetyltransferase

34) Addition of (-COCH3) groups to histone amino terminal tails results in a/an ____________ in gene expression.

increase

6) Which of the following is not part of the lac operon?

lacI

5) The lac repressor binds to what site within the lac operon?

lacO

16) Which region associated with the lac operon is not involved in the binding of RNA polymerase?

lacZ

34) A ____________ is composed of DNA wrapped around an octamer of histone proteins.

nucleosome

24) At which of the following level(s) can gene expression be regulated in eukaryotes?

passage of mRNA through the nuclear membrane, destruction of the mRNA, and rate of protein synthesis

22) RNA polymerase binds to the

promoter.

31) What protein would not interact with a coactivator?

repressors

29) Which of the following statements about basal transcription factors is TRUE?

they are essential for transcription and they cannot increase the rate of transcription by themselves

23) The most efficient control of eukaryotic gene expression is achieved at the level of

transcription initiation.

25) What level of regulation do eukaryotes possess that prokaryotes do not?

transport of RNA out of the nucleus

20) The assembly of transcription factors begins

upstream from the transcription start site.

3) What is the MOST important reason a cell would have translational control over the regulation of gene expression?

At the translational level, protein synthesis can be turned on and off quickly to respond to the needs of the cell.