During the late stage T4 phage infection, the phage DNA is synthesized by Select one: O a. the DNA polymerase encoded by T4 genome. O b. the ADP-ribosylated DNA polymerase encoded by E. coli genome. O c. the ADP-ribosylated DNA polymerase encoded by T4 genome. O d. the DNA polymerase encoded by E. coli genome.

Retroviruses may transform cells in more than one way. From the figure given below, explain the two ways by which cells are transformed. You have the purified protein overexpressed in the cell. How will you determine which pathway of expression is occurring in the cell? Promoter V-onc Retroviral DNA - Retroviral DNA Retroviral Proto- promoter oncogene Proto- V-onc oncogene Host cell DNA - Host cell DNA Excessive Lexpression Expression C-onc V-onc MRNA W MRNA Abnormal protein (hyperactive) Protein product Abnormal cell growth

A researcher identified a mutation in PR of phage λ that causes itstranscription rate to be increased 10-fold. Do you think this mutationwould favor the lytic or lysogenic cycle? Explain your answer.

Which of the following molecules will experience a large change in cytoplasmic concentration whenthe above tryptophan operon is turned on (in E. coli cells)?A. tryptophan molecules will decrease in concentrationB. lactose molecules will decrease in concentrationC. tryptophan molecules will increase in concentrationD. lactose molecules will increase in concentrationE. none of the above

Let’s suppose a drug inhibits the function of the N protein. Would such a drug favor the lysogenic cycle, favor the lytic cycle, or prevent both cycles from occurring?

What environmental conditions favor a switch to the lytic cycle?

A company that manufactures cleansing products has synthesized two new organic compounds , chemicals A and B, which improve the cleaning power of dishwashing detergents. To determine the mutagenic capacity of the chemicals , the company tested the effect of the chemicals on Salmonella cells requiring histidine to grow ( His- cells ). The table below shows the results of the test . A. Name the test used by the company . B. What does the test detect or estimates ? C. Which chemical (s) would you identify as containing a mutagen ? Why ? D. What is the purpose of test 1 ? Why are colonies detected in test 1? E. Which chemical ( s) would you identify as possible antimutagen ? Why ?

nich TWO of the following statements about Extended Spectrum ß-lactamases are CORRECT? O Extended Spectrum ß-lactamases can inactivate all B-lactam antibiotics except third generation antibiotics in this family. O Genetic material encoding for extended spectrum ß-lactamases are easily transferred to other bacteria via transduction. O Extended Spectrum ß-lactamases are frequently produced in Klebsiella sp. and Escherichia coli strains. O Many Extended Spectrum ß-lactamases are not inhibited by clavulanic acid and other B-lactamase inhibitors. OSome Extended Spectrum ß-lactamases-producing E. coli are still sensitive to penicillins. OA new class of Extended Spectrum ß-lactamases has emerged and these have been widely detected among S. epidermidis. O Extended Spectrum ß-lactamases are not effective against the cephalosporin family of antibiotics.