Genetic Engineering Questions and Answers for Entrance exams focuses on “Choosing the Right Mutations, Database of Mutant Lines and Gene Disruption”.
1. The minor change in amino acid sequence can lead to _______ effect on three dimensional structure and there _____ in the primary sequence.
a) huge, may be no change
b) no, may be huge change
c) very less, is very less change
d) huge, would be huge change
Answer: a
Explanation: The minor change in the amino acid sequence can lead to a huge effect on the three dimensional structure and might also abolish its function. In the primary sequence, there might be no change.
2. It is often useful to inactivate endogenous genes in an organism. It might be helpful in finding out _________ role of the wild type gene.
a) biological
b) chemical
c) physiological
d) anatomical
Answer: c
Explanation: Inactivation of endogenous genes in an organism is very important at times. It is helpful in finding out the physiological role of the wild type gene.
3. The inactivation of endogenous genes may also be helpful in directing the expression of the mutated gene in the absence of background expression of wild type gene.
a) True
b) False
Answer: a
Explanation: Inactivation of endogenous genes is very useful. It can be used to direct the expression of the mutated gene in the absence of background expression of wild type gene.
4. How can mutant strains be produced?
a) In systematic mutagenesis programmes
b) In individual organisms
c) Both by individual organisms and systematic mutagenesis programmes
d) Apart from these two, other methods are also used
Answer: c
Explanation: For popular model organisms, there are databases for mutant strains. These mutant strains can either be produced by systematic mutagenesis programmes or by individual organisms.
5. The principle of gene disruption is ________ to replace the endogenous chromosomal copy of a gene with __________
a) homologous recombination, inactivated gene
b) reciprocal translocation, inactivated gene
c) homologous recombination, activated gene
d) reciprocal translocation, activated gene
Answer: a
Explanation: For gene disruption, the basic principle is homologous recombination to replace the endogenous chromosomal copy of a gene with the inactivated gene.
6. The gene to be disrupted is cloned and a selectable marker is inserted. What should be the effect of selectable marker?
a) It should have no effect on target gene
b) It should make the target gene non-functional
c) There is no restriction; it can be either functional or non-functional
d) It should improvise the chances of survival of the target gene
Answer: b
Explanation: In the target gene, a selectable marker should be inserted. It can be either in the form of ampicillin resistance or a nutritional marker. The selectable marker should render the target gene non-functional.
7. The disrupted gene is excised from the vector and is inserted into the target organism. The excised gene should be in which form?
a) Circular
b) Supercoiled
c) Either supercoiled or circular
d) Linear
Answer: d
Explanation: The disrupted gene is excised from the vector and is inserted into the target organism. The excised gene should be linear in form.
8. Stable acquisition of the marker can take place only if a double crossover over the flanking sequence and their chromosomal counterparts causes the marker’s integration into the chromosome.
a) True
b) False
Answer: a
Explanation: The incoming molecule having the marker will not replicate stably because it is linear. For the stable replication, double crossover of the flanking sequence should take place, replacing the endogenous gene with the disrupted gene.
9. If ______ gene is there, the double crossover may leave ________ in the chromosome.
a) linear, functional copy
b) circular, functional copy
c) linear, a non-functional copy
d) circular, a non-functional copy
Answer: b
Explanation: If the disrupted gene is in a circular form, there is a possibility that the double crossover may still leave a functional copy in the chromosome.
10. If the target organism contains more than one copy of the gene, what is the effect on these copies?
a) Only copy is disrupted
b) All the copies are disrupted
c) It is difficult to ensure that all the copies are disrupted
d) Only a specified number of copies are disrupted
Answer: c
Explanation: If more than one copy of the gene is there in the target organism, it is difficult to ensure that all the copies are disrupted. Multiple copies of the gene can be present, if the organism is not haploid.
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