This set of Life Sciences Multiple Choice Questions & Answers (MCQs) focuses on “Protein Synthesis”.
1. Conversion of messages carried by mRNA into amino acid sequences is called___________
a) Replication
b) DNA repair
c) Translation
d) Transcription
View Answer
Explanation: Translation is the process of conversion mRNA base sequences into amino acid sequences.
2. tRNA has peptidal transferase activity.
a) True
b) False
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Explanation: Peptidal transferase activity is performed by rRNA. tRNA functions in bringing amino acid to the ribosome.
3. The following set of RNA is required in the translation process except one, mark the INCORRECT?
a) Si RNA
b) rRNA
c) mRNA
d) tRNA
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Explanation: Three types of RNA are required to perform cooperative functions in protein synthesis i.e, mRNA carries a genetic message, tRNA, and rRNA.
4. What is the size of the prokaryotic ribosome?
a) 80S
b) 70S
c) 40S
d) 60S
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Explanation: The size of prokaryotic ribosome is 70S and it consists of two subunits large (50S) and small (30S).
5. Name the sequence of RNA, which is recognized by a small subunit of the ribosome.
a) Rho utilization site
b) Downstream sequence
c) Upstream sequence
d) Shine Dalgarno sequence
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Explanation: In prokaryotes, Shine Dalgarno sequences are found near the initiation codon and it is complementary to the sequences present on the small subunit of the ribosome.
6. Which of the following is considered as a start codon?
a) AUG
b) GUG
c) UAG
d) AGG
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Explanation: Start codon refers to the first base of sequences from which reading begins and proceed 3 nitrogenous bases at a time.
7. Mark the one, which is NOT a stop codon?
a) UAA
b) UAG
c) UGA
d) GGA
View Answer
Explanation: Out of total codons, there are three non-sense codons or stop codon i.e, UAA (ochre), UAG (Amber), and UGA (opal).
8. Which of the following is not true to the nature of the genetic code?
a) Codon is triplet
b) Codons are commaless
c) Codons are overlapping
d) Codons are universal
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Explanation: Codons are non-overlapping in nature, commaless, and there is no punctuation mark between them. Codons are universal as well, except mammalian mitochondria and some bacteria.
9. Who explained the wobble hypothesis?
a) Darwin
b) Watson and Crick
c) Samuel B. Weiss
d) Nirenberg
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Explanation: In 1966, Watson and Crick proposed the degeneracy wobble hypothesis. Wobble hypothesis explained the ability of an anticodon to base pair with more than one codon.
10. Which of the following recognize a specific amino acid and its cognate t-RNA molecule?
a) t-RNA synthetase
b) Ribososme
c) r-RNA
d) Topoisomerase
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Explanation: The t-RNA synthetase enzyme recognizes a specific amino acid and its cognate t-RNA molecules. There are 20 different enzymes, which are categorized into 2 classes.
11. Name the inhibitor which blocks translation in both prokaryotes as well as eukaryotes?
a) Chlorophenicol
b) Tetracycline
c) Puromycin
d) Streptomycin
View Answer
Explanation: Puromycin is an analog of the amino acyl t-RNA, which causes premature termination of polypeptide.
12. Which of the following inhibitor block translation in eukaryotes?
a) Cyclohexamine
b) Tetracycline
c) Puromycin
d) Streptomycin
View Answer
Explanation: Cyclohexamine inhibits peptidal transferase activity in eukaryotes while chlorophenicol inhibits peptidal transferase in prokaryotes.
13. Name the drug which inhibits the initiation step of translation.
a) Cyclohexamine
b) Tetracycline
c) Ricin
d) Streptomycin
View Answer
Explanation: Streptomycin binds 16S r-RNA and interferes proof reading thus it causes m-RNA misreading and inhibits the initiation step.
Sanfoundry Global Education & Learning Series – Life Sciences.
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