Question

46. What enzyme is used to make cDNA a. Ribozyme b. Reverse transcriptase C. Taq polymerase d. Restriction endonuclease 47. Which of the following requires contact between a virus and a recipient bacterium for transfer of DNA? a. Crossing over b. Mutation c. Transduction d. Conjugation e. Transformation 48. In Recombinant DNA technology a vector is used to inserts the DNA into a host cell True/ False 49. If a foreign gene inserted into a plasmid inactivates the beta-galactosidase gene, a bacterium containing that plasmid would form white colonies on X-gal medium. True / False 50. Viral DNA is an important cloning vector because it can typically be combined with relatively large pieces of DNA SOLO True / False 51. When bacteria are genetically modified to produce a protein product, technical difficulties arise because that product is not always secreted from the cell. True / False 52. Yeasts cannot express foreign, eukaryotic genes. True / False 53. Recombinant DNA cloning have been altered so that they cannot survive outside the laboratory True False

Answer 1

46) cDNA is complementary DNA. cDNA is made using single-stranded RNAs as the template strand, the reverse transcriptase is the enzyme which produces DNA using RNA as the template strand, so the answer is b) reverse transcriptase.

Taq polymerase is the DNA polymerase in the thermophile Thermus aquaticus.

restriction endonucleases are enzymes that cut DNA at specific locations.

47) conjugation is the process by which DNA is transferred from the donor strain (F+ or Hfr) to F- recipient strain via sex pili.

mutations are sudden and heritable changes in the DNA sequence.

transformation is the process by which bacteria take genetic material from the environment.

transduction is the process by which the virus transfers new genetic material into the host cell.

so the answer is d) conjugation.

48) recombinant plasmid contains the gene of interest, the plasmid is the vector, it is transformed into the host cell if the host is a bacteria.

for plants, Ti plasmid is used.

for the animal cells, viruses are used to transfer the DNA to the host cell.

so a vector is required to insert the DNA into the host cell so the given statement is true.

49) beta-galactosidase enzyme can convert X-gal to a blue coloured pigment if new gene is inserted to the beta-galactosidase gene functional enzyme cannot be produced so X -gal cannot be converted to blue so those colonies appear white.

so the given statement is true.