Vector Biology Questions and Answers – Special Vectors for Expression in E.Coli – 2

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This set of Vector Biology Quiz focuses on “Special Vectors for Expression in E.Coli – 2”.

1. What is the most critical component of an expression vector?
a) Terminator
b) Suppressor
c) Inducer
d) Promoter
View Answer

Answer: d
Explanation: The promoter is the most important component of an expression vector because it controls the very first stage of gene expression.
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2. The rate at which messenger RNA is synthesized is determined by ______________
a) Promoter
b) Gene
c) Host
d) Nucleus
View Answer

Answer: a
Explanation: The promoter controls the attachment of RNA polymerase enzyme to the DNA and determines the rate at which messenger RNA is synthesized.

3. The amount of recombinant protein obtained depends on the nature of nature of host.
a) True
b) False
View Answer

Answer: b
Explanation: The amount of recombinant protein obtained depends on the nature of nature of the promoter. The promoter controls the attachment of RNA polymerase enzyme to the DNA and determines the rate at which messenger RNA is synthesized.

4. A small variation in the consensus sequence of a promoter will lead to change in the variation of ______________
a) Efficiency of transcription
b) Translational efficiency
c) Cloning efficiency
d) Host range
View Answer

Answer: a
Explanation: Although most E.coli promoters do not differ much from the consensus sequences, a small variation may have a major effect on the efficiency with which the promoter can direct transcription.

5. For genes whose products are needed in small amounts, which types of promoters are required?
a) Strong promoters
b) Consensus promoters
c) Weak promoters
d) Any promoter
View Answer

Answer: c
Explanation: Weak promoters are inefficient, direct transcription of genes whose products are needed in only small amounts.
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6. Strong promoters sustain a _______ rate of transcription.
a) Medium rate
b) Low rate
c) High rate
d) Average rate
View Answer

Answer: c
Explanation: Strong promoters are those that can sustain a high rate of transcription; strong promoters usually control genes whose translational products are required in large amounts by the cell.

7. Induction and repression are types of ___________
a) Regulation
b) Expression
c) Signals
d) Processes
View Answer

Answer: a
Explanation: An important factor to be considered during construction of an expression vector is that whether it will be possible to regulate the promoter.

8. An inducible gene is the one whose __________ can be switched on by the addition of a chemical to the medium.
a) Translocation
b) Transcription
c) Replication
d) Translation
View Answer

Answer: b
Explanation: An inducible gene is the one whose transcription can be switched on by the addition of a chemical to the medium, which is a substrate.

9. A repressible gene is the one that can be _________
a) Switched off
b) Switched on
c) Expressed
d) Killed
View Answer

Answer: a
Explanation: A repressible gene is switched off by the addition of the regulatory chemical. This chemical is one of the substrates for the enzymes.
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10. High level of transcription may affect the ability of the recombinant plasmid to _____________
a) Express
b) Sustain
c) Replicate
d) Take up DNA
View Answer

Answer: c
Explanation: Regulation of the cloned gene is desirable, as a continuously high level of transcription may affect the ability of the recombinant plasmid to replicate, leading to its eventual loss from the culture.

11. The “tac promoter” is induced by _______
a) Lactose
b) Amylose
c) Lactose
d) IPTG
View Answer

Answer: d
Explanation: The “tac promoter” is a hybrid between the trp and lac promoters. It is stronger than either but still induced by IPTG.

12. The “lac promoter” is the sequence that controls transcription of _____________
a) LacZ’ gene
b) Trp gene
c) Lambda DNA
d) Amylose
View Answer

Answer: a
Explanation: The “lac promoter” is the sequence that controls transcription of LacZ’ gene, coding for beta-galactosidase.

13. Tryptophan synthesis is controlled by _________
a) Lac promoter
b) Trp promoter
c) Tac promoter
d) Lambda promoter
View Answer

Answer: b
Explanation: The trp promoter is normally upstream of the cluster of genes coding for several of the enzymes involved in the biosynthesis of the amino acid tryptophan.
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14. The lac promoter is induced by _____
a) IPTG
b) Lactose
c) Tryptophan
d) Amylose
View Answer

Answer: a
Explanation: The lac promoter is induced by isopropylthiogalactosidase (IPTG), so an addition of a gene inserted downstream of the lac promoter.

15. Lambda P L promoter is responsible for the transcription of ____________
a) Lambda DNA
b) Lambda RNA
c) Tryptophan
d) IPTG
View Answer

Answer: a
Explanation: Lambda P L promoter is responsible for the transcription of lambda DNA. It is a very strong promoter recognized by a polymerase.

Sanfoundry Global Education & Learning Series – Vector Biology & Gene Manipulation.

To practice all areas of Vector Biology for Quizzes, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn