When the phage DNA enters a bacterium, it protects itself from the viral DNA with the help of:
1. | methylases | 2. | endonucleases |
3. | exonucleases | 4. | ligases |
An important limitation of the use of Agrobacterium tumefaciens is that it cannot:
1. | infect dicots |
2. | be genetically modified |
3. | be cultured on a nutrient medium |
4. | infect crop plants such as wheat and corn |
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 |
Restriction enzymes are synthesized by:
1. | bacteria only | 2. | yeast and bacteria |
3. | eukaryotic cells only | 4. | all kinds of cells |
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 |
A danger of genetic engineering is that the genetically modified bacterium can escape the lab and infect humans. This possibility is prevented by:
1. | selecting a mutant form of the bacteria |
2. | selecting a live attenuated bacterium |
3. | application of stringent asepsis in the lab |
4. | prophylactically immunizing the persons working in the lab |
A DNA library is:
1. | information in a computer database about all the genes sequenced so far |
2. | a collection of vectors in a molecular biology lab |
3. | a collection of fragments of DNA that make up the entire genome of an organism |
4. | all the restriction sites put together on a DNA fragment |
A foreign DNA was introduced at a cloning site within the gene for beta-galactosidase in a plasmid of a bacterium. The bacterium containing this rDNA was plated on a medium containing X-gal. They were distinguished by the fact that they remained white. This method should be called as:
1. | selection | 2. | screening |
3. | transformation | 4. | transduction |
Cohen and Boyer constructed one of the first genetically engineered chimeras, pSC101. They introduced in this plasmid the gene of Xenopus laevis that coded for:
1. | cytochrome c | 2. | haemoglobin |
3. | keratin | 4. | rRNA |
If the required gene has been isolated by shotgun approach, care must be taken to:
1. | cut the plasmid with a different restriction enzyme than that used to obtain the donor gene |
2. | cut the plasmid with the same restriction enzyme that was used to obtain the donor gene |
3. | avoid cutting the plasmid |
4. | cut the plasmid with two different restriction enzymes |