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