This set of Genetic Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Promoters”.
1. Some vectors carry a mutant form of promoter known as lacUV5 promoter. It carries ______ in the promoter region and _____ the efficiency.
a) point mutations, decreases
b) point mutations, increases
c) frameshift mutations, increases
d) frameshift mutations, increases
Explanation: In some vectors, lacUV5 promoter is present. It is a mutant form and carries point mutations which increase the efficiency.
2. Lambda PL promoter is used in which vectors?
a) Cloning vectors
b) Expression vectors
c) Both cloning and expression vectors
d) Bacteriophage Mu
Explanation: Lambda PL promoters are the promoters for the left region in bacteriophage lambda. It is widely used in expression vectors.
3. The promoter can be controlled by a repressor which is temperature sensitive.
Explanation: The promoter is activated at a temperature higher than 30 degrees because at this temperature repressor is inactivated.
4. Choose the correct statement for rifampcin.
a) It inactivates both E. coli polymerase and T7 polymerase
b) It activates both E. coli polymerase and T7 polymerase
c) It inhibits T7 polymerase but doesn’t inhibits E. coli polymerase
d) It inhibits E. coli polymerase but doesn’t inhibits T7 polymerase
Explanation: Rifampcin is added in order to reduce the transcription of other genes. It inhibits the E. coli RNA polymerase but doesn’t inhibit the T7 polymerase.
5. The ______ operon encodes proteins involved in arabinose metabolism.
Explanation: The araBAD operon encodes proteins involved in arabinose metabolism. It is controlled by AraC transcriptional regulator.
6. tac promoter is an example of which type of promoter?
a) hybrid promoter
b) fusion promoter
c) lacZ promoter
d) araBAD promoter
Explanation: Hybrid promoters are those promoters which are produced by two promoters from different sources. Tac promoter is a hybrid promoter produced from trp promoter and lacUV5 promoter.
7. The tac promoter is made by _____ region of trp promoter and _____ region of the lacUV5 promoter.
a) 10, 35
b) 35, 10
c) 10, 10
d) 35, 35
Explanation: It is a hybrid promoter made by 35 regions of trp promoter and 10 regions of the lacUV5 promoter.
8. The tac promoter includes the lac operator and is regulated by a repressor.
Explanation: The tac promoter includes the lac operator and is regulated by the repressor. The repressor is to be supplied by the host.
9. Expression of T7 promoter- lac operator hybrid requires ___________
a) T7 RNA polymerase
b) An inducer such as IPTG
c) Both T7 RNA polymerase and inducer such as IPTG
d) T7 DNA polymerase
Explanation: Expression of T7 promoter- lac operator hybrid requires both T7 RNA polymerase and inducer such as IPTG. If inducer is absent levels of expression are very low.
10. When lacUV5 control system is used, addition of IPTG _______ the expression of _________
a) activates, T7 RNA polymerase
b) inactivates, T7 RNA polymerase
c) activates, T7 DNA polymerase
d) inactivates, T7 DNA polymerase
Explanation: When a lacUV5 control system is used, the addition of IPTG activates the expression of T7 RNA polymerase. Thus transcription of sequences under the control of T7 promoter is controlled.
Sanfoundry Global Education & Learning Series – Genetic Engineering.
To practice all areas of Genetic Engineering, here is complete set of 1000+ Multiple Choice Questions and Answers.