Genetic Engineering Multiple Choice Questions on “Expression in Vivo”.
1. If overexpression of proteins takes place, they become toxic at times. In such a case _______ colonies are recovered after ______ with the recombinant plasmid.
a) few, translation
b) few, transformation
c) no, transformation
d) no, translation
Answer: c
Explanation: At times, overexpression of proteins takes place. It leads to toxicity. In such a case, no colonies are recovered after transformation with the recombinant plasmid. It is so because no colonies survive because of overexpression of the protein.
2. Ribosome binding site in E.coli is composed of which sequence primarily?
a) -GAGG-
b) -CTCC-
c) -ATGG-
d) -CGTT-
Answer: a
Explanation: Ribosome binding site is responsible for initiating translation. It is composed of –GAGG- sequence primarily.
3. Translation starts at first _____ codon in the mRNA downstream from the ribosome binding site.
a) ACG
b) AUG
c) UAC
d) CAG
Answer: b
Explanation: Translation starts at first AUG codon in the mRNA downstream from the ribosome binding site. It is the start codon.
4. Expression of cloned sequences in E.coli requires a promoter, a ribosome binding site and an initiation codon.
a) True
b) False
Answer: a
Explanation: Expression of cloned sequences in E. coli requires a promoter, a ribosome binding site and an initiation codon. Initiation codon is the start codon AUG.
5. If an expression vector contains all three, viz. a controllable promoter, a ribosome binding site and an initiation codon, then a hybrid protein is produced. The _______ region of hybrid protein is encoded by vector and the rest is expressed by the sequence inserted.
a) N terminal
b) C terminal
c) Both N & C terminal
d) Middle
Answer: a
Explanation: If all three elements are present, then a hybrid protein is formed. The N terminal region of the hybrid protein is encoded by the vector and the rest is expressed by the sequence inserted.
6. Proteins synthesized by carrying out a translation of the vector region and continuing it in the insert region is called as _____________
a) hybrid protein
b) fusion protein
c) combination protein
d) insert protein
Answer: b
Explanation: At times, translation of vector is carried out and is continued in the insert. Proteins produced by this method are known as fusion proteins.
7. It is also possible to generate a fusion protein in which ______ is encoded by the vector.
a) N terminal
b) C terminal
c) Both N and C terminal
d) Middle region
Answer: b
Explanation: Generally, N terminal is encoded by the vector. But at times it is also possible to generate a fusion protein by encoding C terminal.
8. Which of the following is present in E. coli rrnB operon for rRNA?
a) Initiation codon
b) Termination codon
c) Both initiation and termination codon
d) Both are absent
Answer: c
Explanation: Initiation codon is present in all expression vectors, but few are also having termination codons. It is necessary to stop high levels of transcription.
9. Termination codon is required for stopping high levels of transcription of other regions such as _______ which might interfere with ___________ of the vector.
a) origin, replication
b) end, replication
c) end, stability
d) origin, stability
Answer: d
Explanation: Termination codon is required for stopping high levels of transcription of other regions such as origin. Other regions might interfere with the stability of the vector.
10. In fusion proteins, the reading frame in a vector is out of phase with the insert.
a) True
b) False
Answer: b
Explanation: Fusion proteins are the proteins produced by carrying the translation in vector region and then continuing it in insert region. Hence, to carry out this, the reading frame should be in phase.