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Genetic Engineering Multiple Choice Questions on “Bacteria”.
1. An organism containing a gene which doesn’t belong to it and is derived from somewhere else then the organism is said to be ___________
a) transformed
b) transgenic
c) mutant
d) modified
Answer: b
Explanation: An organism which contains a gene which doesn’t belong to it and is derived from somewhere else, it is said to be transgenic.
2. E.coli is a gram negative bacterium.
a) True
b) False
Answer: a
Explanation: There are basically two types of bacteria, gram negative and gram positive. E.coli is a gram negative bacterium. These two groups are having properties which make them different.
3. If a host other than E.coli is to be used, what property of DNA to be inserted is disadvantageous?
a) Circular DNA
b) Linear DNA
c) Replicating DNA
d) Non-replicating DNA
Answer: c
Explanation: If the DNA is to be inserted in a host other than E.coli than the DNA can be circular or linear and it should be non-replicating. As it is non-replicating, it can be stably maintained in the host only by integration into replicon.
4. If plasmids direct their own transfer from one bacterium cell to another, then they are called as ___________
a) self-transmissible
b) auto-transmissible
c) autonomously replicating
d) auto-transfer
Answer: a
Explanation: It is important to transfer the plasmids from one bacterium to another. If, plasmids are able to direct their own transfer, then it is called as self-transmissible. There are some plasmids which do it with the help of other plasmids.
5. If a plasmid can’t be transferred from one cell to another, then it is called as ___________
a) non-transmissible
b) non-mobilizable
c) untransferrable
d) immobilized
Answer: b
Explanation: Some plasmids can’t be transferred from one cell to another even with the help of other plasmids. Such plasmids are said to be non-mobilizable.
6. Choose the incorrect statement for shuttle vectors.
a) These are vector hybrids constructed from E.coli and other plasmids
b) They are having a varied use
c) They can replicate and selected in both the species
d) They are the plasmids which are having naturally broad host range
Answer: d
Explanation: Shuttle vectors are those vector hybrids which are constructed artificially with the help of E.coli and other plasmids. They are able to replicate and selected in both the species and thus they are having a varied use. These are the plasmids which are having artificially broad host range because of the introduction of an extra origin of replication.
7. Which of the bacteria are used as hosts?
a) Gram-positive
b) Gram-negative
c) Both gram positive and negative are preferred equally
d) Both can be used but gram positive is preferred
Answer: d
Explanation: Gram positive bacteria are particularly used as hosts. It is so because they secrete the expressed proteins in the growth medium at a much higher rate.
8. Basically, there are how many methods for introduction of DNA into the bacterial cells?
a) 1
b) 2
c) 3
d) 4
Answer: c
Explanation: There are basically three methods for introduction of DNA into the bacterial cells. These are the introduction of naked DNA, transformation of protoplasts and conjugation.
9. Gram-positive Bacillus, Streptococcus and Streptomyces include species that don’t exhibit natural competence.
a) True
b) False
Answer: b
Explanation: These include species which exhibit natural competence. It means that they take up DNA without any physiological treatment.
10. Competence is determined by the excretion into growth medium of _______ & _________ proteins called as competence proteins.
a) cellular & high molecular weight
b) cellular & low molecular weight
c) extracellular & low molecular weight
d) extracellular & high molecular weight
Answer: c
Explanation: Competence proteins are the proteins which are extracellular and low molecular weight and they help in determination of competence. Competence further develops as cell density.
11. Natural transformation can be relieved by the use of protoplasts, in the presence of osmotic buffer and polyethylene glycol. What are protoplasts?
a) Protoplasts are the cells from which cell membrane has been removed
b) Protoplasts are the cells from which cell wall has been removed
c) Protoplasts are the cells from which vacuole has been removed
d) Protoplasts are the cells from which golgi bodies are removed
Answer: b
Explanation: Protoplasts are the cells from which the cell wall has been removed. They help in relieving natural transformation in the presence of osmotic buffer and polyethylene glycol.
12. Transfer of plasmids from one cell to another can also be done conjugation. The plasmid to be transferred known as ______ is often unable to do so by itself and thus it relies on other plasmids known as ______
a) cargo, conjugal
b) conjugal, cargo
c) cargo, helper
d) conjugal, helper
Answer: a
Explanation: Plasmids can also be transferred from one cell to another through conjugation. Plasmids which are unable to transfer themselves are referred as cargo plasmids and they often rely on other plasmids which are called as conjugal plasmids. At times, helper plasmids are used in order to protect cargo plasmids from degradation.
13. The transfer of plasmid from one bacterial cell to another when cargo and conjugal plasmids are used, it is usually is carried out by _____ mating.
a) diparental
b) uniparental
c) triparental
d) multiparental
Answer: c
Explanation: The transfer is carried out by triparental mating. Three conjugants are used, E.coli carrying the conjugal plasmid, E.coli containing cargo and helper plasmid and the recipient bacterial species to be manipulated.