Vector Biology Multiple Choice Questions on “Special Vectors for Expression in E.Coli – 1”.
1. If a foreign gene is simply ligated into a standard vector, it is likely that a recombinant protein will be produced.
A. True
B. False
Answer: B
Clarification: If a foreign gene is simply ligated into a standard vector and cloned in E.coli, it is very unlikely that a significant amount of recombinant protein will be synthesized.
2. What are the signals, inside the host that surround the gene?
A. Amino acids
B. Nucleotides
A. Proteins
D. Bacterium
Answer: B
Clarification: Expression is dependent on gene being surrounded by a collection of signals that can be recognized by the bacterium. These signals are short sequences of nucleotides.
3. Which of the following is not an important signal for the E.coli genes?
A. Promoter
B. Terminator
A. Inducer
D. Ribosome binding site
Answer: C
Clarification: Promoters, terminators and ribosome binding site are all important signals for E.coli genes. However, the inducer is not an essential signal.
4. Which of the following process is initiated by the promoter?
A. Translation
B. Replication
A. Apoptosis
D. Transcription
Answer: D
Clarification: The promoter, which marks the point at which transcription of the gene should start. In E.coli the promoter is recognized.
5. The promoter is recognized by ______________
A. RNA polymerase
B. DNA polymerase
A. Replicase
D. Helicase
Answer: A
Clarification: The promoter, which marks the point at which transcription of the gene should start. In E.coli the promoter is recognized by the RNA polymerase.
6. The terminator _______ the transcription process.
A. Decreases
B. Increases
A. Activates
D. Ceases
Answer: D
Clarification: The Terminator, marks the point at the end of the gene where transcription should stop. The terminator sequence can base-pair with itself to form a stem-loop structure.
7. A tem-loop structure in an E.coli cell is formed by __________
A. Gene
B. Terminator
A. Inducer
D. Promoter
Answer: B
Clarification: A terminator is usually a nucleotide sequence that can base pair with itself to form a stem loop structure. Terminator marks the end of the transcription process.
8. Ribosome binding site is recognized by __________
A. Polymerase
B. Ribosome
A. Nucleosome
D. Chromosome
Answer: B
Clarification: The ribosome binding site, a short nucleotide sequence recognized by the ribosome as the point at which it should attach to the messenger RNA molecule.
9. The initiation codon of the gene is located ___________ of the ribosome binding site.
A. Upstream
B. Downstream
A. Away
D. Inside
Answer: B
Clarification: The initiation codon of the gene is always a few nucleotides downstream of the ribosome binding site.
10. The ‘TTGACA Box’ signal is found only in ___________
A. Plants
B. Animals
A. Fungi
D. E.coli
Answer: D
Clarification: The genes of higher organisms are also surrounded by expression signals, but their nucleotide sequences are not the same as the E.coli versions.
11. The ‘TATA Box’ in animals contains one more ______ as compared to that present in E.coli.
A. Adenosine
B. Cytosine
A. Thymine
D. Guanine
Answer: A
Clarification: The genes of higher organisms are also surrounded by expression signals, but their nucleotide sequences are not the same as the E.coli versions.
12. The ‘TATA Box’ is present at _____ in animals and at _______ in E.coli.
A. -25, -10
B. -10, -10
A. -10, -25
D. -25, -25
Answer: A
Clarification: The genes of higher organisms are also surrounded by expression signals, but their nucleotide sequences are not the same as the E.coli versions.
13. What could be a possible reason for non-expression of a foreign gene in an E.coli host?
A. Recognition of expression signals
B. Non-recognition of expression signals
A. Indefinite size
D. Inefficient ligation
Answer: B
Clarification: A foreign gene is inactive in E.coli, simply because the bacterium does not recognize its expression signals.
14. Cloning vectors that can be used for recombinant protein production are called _____________
A. Expression vectors
B. Hybrid vectors
A. Hosts
D. Advanced vectors
Answer: A
Clarification: Expression vectors are the cloning vectors that provide expression signals and therefore can be used in the production of recombinant protein.
15. Placing a foreign gene under the control of expression signals will lead to its ____________
A. Activation
B. Expression
A. Inactivation
D. Knockout
Answer: B
Clarification: If a foreign gene is inserted into the vector in such a way that it is placed under the control of a set of E.coli expression signals.