Q. No.Restriction enzymes do not act on the DNA of the host cell in which they are produced, because :
| 1. | Host DNA is packed into chromosomes |
| 2. | Restriction enzymes are ineffective on host DNA |
| 3. | Host DNA does not have the restriction site for the restriction enzymes. |
| 4. | Restriction site of host DNA is methylated. |
DNA fragments resulting from restriction enzyme digestion are moved through agar gel during electrophoresis. Which of the following modifications to the fragments will not affect the rate of their movement?
1. Neutralizing the negative charge
2. Increasing length
3. Changing the base composition
4. Decreasing length
Consider the following statements:
| I: | Asexual reproduction preserves genetic information while sexual reproduction permits variations. |
| II: | Traditional hybridization often leads to the inclusion and multiplication of undesirable genes along with the desired genes. |
| III: | rDNA technology allows us to isolate and introduce only one or a set of desirable genes without introducing undesirable genes in the target organism. |
Which of the above statements are true?
| 1. | I and II only | 2. | I and III only |
| 3. | II and III only | 4. | I, II, and III |
In the first gene cloning experiment:
| 1. | Researchers successfully identified a human gene responsible for the disease. |
| 2. | Researchers successfully inserted a gene for kanamycin resistance into a plasmid vector. |
| 3. | Researchers demonstrated that many different DNA fragments could insert into a plasmid vector |
| 4. | Researchers produced a strain of bacteriophage with an increased ability to infect E. coli. |
To isolate DNA in pure form from a bacterial cell, it should initially be treated with:
| 1. | Proteases and RNase but not DNase | 2. | Lysozyme |
| 3. | Restriction endonuclease | 4. | DNA ligase |
The significance of the 'heat shock' method in bacterial transformation is to facilitate:
| 1. | Binding of DNA to the cell wall |
| 2. | Uptake of DNA through membrane transport proteins |
| 3. | Uptake of DNA through transient pores in the bacterial cell wall |
| 4. | Expression of antibiotic resistance gene |
A bacterial cell was transformed with a recombinant DNA molecule that was generated using a human gene. However, the transformed cells did not produce the desired protein. The reasons could be:
| 1. | Human genes may have intron which bacteria cannot process |
| 2. | Amino acid codons for humans and bacteria are different |
| 3. | Human protein is formed but degraded by bacteria |
| 4. | All of the above |
The first type II restriction endonuclease discovered that could cut dsDNA at a specific site was:
| 1. | EcoRI | 2. | SmaI |
| 3. | Hind II | 4. | Hind III |
‘Downstream processing’ does not include:
| 1. | Product biosynthesis | 2. | Product isolation |
| 3. | Product purification | 4. | Product polishing |
Identify a character that is not desirable in a cloning vector:
| 1. | an inactive promoter |
| 2. | an origin of the replication site |
| 3. | selectable markers such as genes for antibiotic resistance |
| 4. | one or more unique restriction endonuclease sites |
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