Choose the best answer.

1		Transcriptional regulation:
			A)	Is highly efficient at completely preventing transcription.
			B)	Allows the cell to only produce proteins that are needed at the time.
			C)	Can be induced by a repressor protein.
			D)	All of these.
			E)	None of these.
2		A gene which is usually turned down but can be activated is under negative control.
			A)	True
			B)	False
3		Which of the following would you expect to find in an inducible system?
			A)	A repressor protein, which is bound to DNA in absence of any other factor.
			B)	A repressor protein, which is bound to DNA in the presence of a corepressor.
			C)	An activator protein, which is bound to DNA in absence of any other factor.
			D)	An activator protein, which is bound to DNA only in the absence of an inhibitor.
4		Which of the following would be an example of enzyme adaptation?
			A)	Enzymes required for glucose utilization are constitutively expressed.
			B)	Addition of phosphate groups to a protein can activate it.
			C)	Certain enzymes are made up of multiple subunits.
			D)	Enzymes for tryptophan synthesis are not made in the presence of tryptophan.
5		Genes within an operon:
			A)	Tend to be regulated by a common regulatory mechanism.
			B)	Are generally involved in the same biochemical pathway.
			C)	Are expressed as a polycistronic RNA.
			D)	All of the above.
			E)	None of the above.
6		What effect would you expect if gene expression of the lac operon were completely repressed?
			A)	The cell would be more efficient without "wasting" the energy required for the low level of lacZ, lacY, and lacA gene expression.
			B)	Allolactose would accumulate within the cell and become toxic.
			C)	Lactose would not be converted into the inducer and the operon could not be induced.
			D)	All of these.
			E)	A and B only.
7		All of the genes involved in functioning of the lac operon are inducible.
			A)	True
			B)	False
8		Which of the following genes is not a structural gene of the lac operon?
			A)	lacA
			B)	lac I
			C)	lacY
			D)	lacZ
9		The inducer for the lac operon is:
			A)	lactose
			B)	allolactose
			C)	β-galactosidase
			D)	galactose
10		The most convincing evidence that lacI is a diffusible protein is:
			A)	A merozygote with only one functional lacI gene is able to regulate both copies of the lac operon.
			B)	A merozygote with only one functional lacO is unable to regulate both copies of the lac operon.
			C)	The lacI gene is located very close to the lac operon.
			D)	Mutants lacking lacI function do not respond to changes in lactose concentration.
			E)	All of the above.
11		Catabolite repression requires an inducer and an activator protein.
			A)	True
			B)	False
12		Which of the following elements, when nonfunctional, would lead to a reduction in the total amount of functional lacZ produced by a bacterial cell?
			A)	The operator.
			B)	The lacI gene.
			C)	The CAP site.
			D)	The lacA gene.
			E)	The lacY gene.
13		Which of these describes a similarity between the lac and ara operons?
			A)	Expression of structural genes does not occur at high glucose concentrations.
			B)	lacI and araI both encode trans acting factors.
			C)	Binding of a regulatory protein is prevented in the presence of an inducer.
			D)	All of these are similarities.
			E)	None of these are similarities.
14		Attenuation of the trp operon:
			A)	Occurs when transcription is complete before translation begins.
			B)	Is mediated by the trp repressor protein.
			C)	Occurs in the presence of high levels of tryptophan.
			D)	All of the above.
			E)	None of the above.
15		What is the best explanation for the stem loop arrangement seen in the absence of translation of the trpL gene?
			A)	Region 4 binds to region 3 before region 2 has been transcribed.
			B)	Region 1 is unable to bind to region 3 or 4.
			C)	The 1:2 stem loop has more base pairs than a 2:3 stem loop.
			D)	The ribosome prevents region 1 from binding to any other region.
16		Why does the ribosome stall on region 1 during attenuation?
			A)	Translation of this region requires tRNAtrp.
			B)	High levels of tryptophan interfere with ribosome function.
			C)	Low levels of tryptophan lead to intrinsic termination.
			D)	Binding of the repressor protein prevents further translation.
17		A translational regulatory protein:
			A)	Binds to DNA and prevents translation.
			B)	Binds to mRNA and prevents translation.
			C)	Binds to rRNA and prevents translation.
			D)	Binds to tRNA and prevents translation.
18		How might antisense RNA affect translation?
			A)	It can interfere with ribosome binding by blocking binding sites.
			B)	It can enhance ribosome binding by modifying binding sites.
			C)	It can prevent identification of the start codon by the ribosome.
			D)	It can interfere with the normal secondary structure of the mRNA molecule.
19		An allosteric enzyme:
			A)	Has two different binding sites.
			B)	Is regulated by binding of a regulatory molecule somewhere other than the active site.
			C)	May be regulated by feedback inhibition.
			D)	Is an example of posttranslational regulation.
			E)	All of these.
20		Induction is the process by which phage λ enters the lysogenic life cycle.
			A)	True
			B)	False
21		After phage λ initially enters a bacterial cell, activation of the early promoters:
			A)	Directs synthesis of an antiterminator protein.
			B)	Prevents accumulation of the cII/cIII complex.
			C)	Is controlled by levels of nutrients in the cell.
			D)	Leads directly to lysis of the cell.
22		Functions of the λ repressor protein include all of the following except:
			A)	Inhibition of the PR promoter for the cII gene, preventing activation of the PRE promoter.
			B)	Activation of high levels of its own expression.
			C)	Inhibition of the PL promoter, preventing activation of the lytic cycle.
			D)	Binding to OR and OL.
23		PR and PRM:
			A)	Activate transcription of the same genes under different regulation.
			B)	Prevent establishment of the lytic cycle when activated.
			C)	Stimulate transcription in opposite orientations on the phage λ DNa.
			D)	All of these.
			E)	None of these.
24		How does the expression of Q protein lead to the lytic cycle?
			A)	The Q protein functions as an antiterminator.
			B)	The Q protein stimulates production of the coat proteins for assembly of new phage.
			C)	The Q protein interacts with RNA polymerase.
			D)	All of these.
			E)	None of these.
25		Presence of cellular proteases that degrade cII:
			A)	Prevents activation of the lytic cycle.
			B)	Is typical under poor growth conditions.
			C)	Allows high levels of expression of the λ repressor protein.
			D)	All of these.
			E)	None of these.
26		The cro protein and λ repressor proteins bind to the same sites within OR.
			A)	True
			B)	False
27		If regulation of a gene involves a repressor protein, it is an inducible gene.
			A)	True
			B)	False
28		The lac repressor protein can repress the operon by binding to any one of the three binding sites in the operator.
			A)	True
			B)	False