This set of Genetic Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Vectors”.
1. What will be the consequence of not having an origin of replication (ori) in the vector?
a) If an ori is absent, replication of vector would not take place
b) As the cells divide after taking up the vector, both the daughter cells would be having the vector
c) A colony of transformed colonies is observed
d) The vector won’t be taken up by the cell
View Answer
Explanation: In the case ori is absent, the vector won’t be able to replicate. As the replication won’t take place, only one of the daughter cells would be having the vector. A colony of transformed colonies won’t be obtained. The puc18 ori came from a plasmid in clinical bacterial isolate and was called as pMB1.
2. It is required to distinguish between the cells that have taken up the vector and that have not. It is done by using __________
a) multiple cloning site
b) origin of replication
c) high copy number
d) selectable marker
View Answer
Explanation: Whether the cell has taken up the vector or not is distinguished by using a selectable marker. A selectable marker often used is the ampcillin resistance property. Cells having the plasmid or vector show resistance against ampicillin.
3. Multiple cloning site (MCS) is defined as __________
a) site within the plasmid which contains a site for many restriction enzymes
b) site within the plasmid which contains a site for many restriction enzymes and they are not present anywhere else in the plasmid
c) as the site containing many sites for only one restriction enzyme
d) cloning many inserts together
View Answer
Explanation: MCS is defined as a location in the plasmid which is having the site for many restriction enzymes and they are not present anywhere else in the plasmid.
4. Size of the vector is related to having a suitable single restriction site.
a) True
b) False
View Answer
Explanation: The size of vector is related to having a suitable single restriction site. It is so because; if the vector is large in size there are more chances of having that sequence in the vector.
5. If a restriction site is 6 nucleotides long, what are the chances of finding it in a vector?
a) Once every 46 base pairs
b) Once every 64 base pairs
c) Once every 24 base pairs
d) Once every 16 base pairs
View Answer
Explanation: If a restriction site is 6 nucleotides long, the chances for having it in a vector are once in every 46 base pairs. It is so because there are 4 nucleotides which form the DNA and at six positions, they can form 46 combinations.
6. Which of the statement is true for pBR322?
a) It contains only an ampicillin resistance gene
b) It contains both ampicillin resistant and tetracycline resistant gene
c) The cloning site is present only in the ampicillin resistant gene
d) It is a natural vector
View Answer
Explanation: pBR 322 is the man-made vector. It contains both ampicillin resistant and tetracycline resistant genes. The cloning site is also present in both of the genes.
7. If a plasmid is having two antibiotic resistant genes, say ampicillin resistant and chloramphenicol resistant. If the plasmid grows in ampicillin containing medium but not in chloramphenicol, what can be concluded?
a) The insert is not present in any of the gene
b) The insert is present in ampicillin gene but not in chloramphenicol gene
c) The insert is present in choramphenicol gene but not in ampicillin gene
d) The insert is present between both of the genes
View Answer
Explanation: The insert is present in the chloramphenicol gene and not in the ampicillin gene. As the insert is present in it, it disrupts its function and hence they are not able to grow in chloramphenicol containing a medium.
8. If high copy number is there, the replication is called as ______ and if low copy number is there the replication is called as ______
a) stringent, relaxed
b) relaxed, stringent
c) relaxed, relaxed
d) stringent, stringent
View Answer
Explanation: If high copy number is there, the replication is known as stringent and if the copy number is low, the replication is known as relaxed.
9. Chloramphenicol amplification is carried out in various plasmids. Which of the statement is incorrect for it?
a) It is used for increasing copy number in plasmids containing pMB1 origin
b) Chloramphenicol promotes bacterial protein synthesis
c) The protein synthesis is responsible for chromosomal DNA replication
d) Chromosomal DNA replication is related to cell division
View Answer
Explanation: Chloramphenicol amplification is used for increasing the copy number in plasmids containing the pMB1 origin. It is responsible for inhibiting bacterial protein synthesis. As the bacterial protein synthesis is inhibited, chromosomal DNA replication is also inhibited. Chromosomal DNA replication is related to cell division and it is also blocked. But the plasmid replication is not inhibited and it replicates.
10. The phenomenon of not allowing the recombinants to escape into the environment is termed as __________
a) blocking
b) termination
c) disablement
d) inactivation
View Answer
Explanation: The phenomenon of not allowing the recombinants to escape into the environment is termed as disablement. It can be achieved by disabling the mob gene, it is responsible for mobilization required for conjugation to take place.
Sanfoundry Global Education & Learning Series – Genetic Engineering.
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