Molecular Biology – Translation: NEET MCQs with Answers

15 free questions on Molecular Biology – Translation for NEET (UG), starting with previous-year NEET and AIPMT questions. Try each one, then tap Show answer for the answer and a short explanation.

Syllabus covered: Translation

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Question 1

Previous-year question
Many ribosomes may associate with a single mRNA to form multiple copies of a polypeptide simultaneously. Such strings of ribosomes are termed [NEET 2018]
  1. Polysome
  2. Polyhedral bodies
  3. Nucleosome
  4. Plastidome
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Answer: (A) Polysome
Explanation: A polysome is a group of ribosomes translating one mRNA at the same time. It greatly increases the rate at which a particular protein can be produced by the cell.

Question 2

Previous-year question
A complex of ribosomes attached to a single strand of mRNA is known as a [NEET 2016]
  1. Polysome
  2. Polymer
  3. Polypeptide
  4. Okazaki fragment
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Answer: (A) Polysome
Explanation: Several ribosomes can translate the same mRNA simultaneously, forming a polysome or polyribosome. This allows many copies of the same polypeptide to be produced at once from a single message.

Question 3

Previous-year question
The process of translation is [AIPMT 1993]
  1. ribosome synthesis
  2. protein synthesis
  3. DNA synthesis
  4. RNA synthesis
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Answer: (B) protein synthesis
Explanation: Translation is the process of protein synthesis in which the triplet base sequence of the mRNA molecule is converted into the specific sequence of amino acids of a polypeptide chain. It takes place on ribosomes.

Question 4

Previous-year question
The translation termination triplet is [AIPMT 1996]
  1. UAU
  2. UAA
  3. UAC
  4. UGC
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Answer: (B) UAA
Explanation: There are three termination codons — UAA (ochre), UAG (amber) and UGA (opal). Of the options given only UAA is a stop codon; UAU and UAC code for tyrosine and UGC for cysteine.

Question 5

Previous-year question
Which is not involved in protein synthesis? [AIPMT 1994]
  1. Transcription
  2. Initiation
  3. Elongation
  4. Termination
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Answer: (A) Transcription
Explanation: Transcription is the synthesis of RNA on a DNA template and is not part of translation itself. Protein synthesis (translation) occurs in three stages: initiation, elongation and termination.

Question 6

Previous-year question
The RNA that picks up specific amino acid from amino acid pool in the cytoplasm to ribosome during protein synthesis is called [AIPMT 1997]
  1. mRNA
  2. tRNA
  3. rRNA
  4. RNA
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Answer: (B) tRNA
Explanation: tRNA carries amino acids to the ribosome during protein synthesis. It has two ends, one that binds a specific amino acid and an anticodon end that pairs with the corresponding codon on the mRNA.

Question 7

Previous-year question
Protein synthesis in an animal cell takes place [AIPMT 1997]
  1. only in the cytoplasm
  2. in the nucleolus as well as in the cytoplasm
  3. in the cytoplasm as well as in mitochondria
  4. only on ribosomes attached to a nucleus
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Answer: (C) in the cytoplasm as well as in mitochondria
Explanation: Translation occurs on ribosomes, which are found free in the cytoplasm and attached to the endoplasmic reticulum, and also inside mitochondria, which possess their own 70S ribosomes. Hence protein synthesis occurs in the cytoplasm as well as in mitochondria.
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Question 8

Previous-year question
Initiation codon of protein synthesis (in eukaryotes) is [AIPMT 2000, 1999, 1994, 1993]
  1. GUA
  2. GCA
  3. CCA
  4. AUG
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Answer: (D) AUG
Explanation: At the 5'-end of the mRNA, where protein synthesis begins, the codon AUG is present. It is therefore called the initiating or start codon and also codes for methionine.

Question 9

Previous-year question
'Signal hypothesis' for the biosynthesis of secretory type of proteins was proposed by [AIPMT 2000]
  1. Camillo Golgi
  2. Baltimore
  3. Blobel and Sabatini
  4. Sheeler and Bianchi
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Answer: (C) Blobel and Sabatini
Explanation: David Sabatini and G. Blobel proposed the signal sequence hypothesis, according to which a short amino acid sequence at the amino terminus of a newly synthesised polypeptide directs the protein to its appropriate destination.

Question 10

Previous-year question
During translation initiation in prokaryotes, a GTP molecule is needed in [AIPMT 2003]
  1. association of 30S, mRNA with formyl met tRNA
  2. association of 50S subunit of ribosome with initiation complex
  3. formation of formyl met tRNA
  4. binding of 30S subunit of ribosome with mRNA
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Answer: (A) association of 30S, mRNA with formyl met tRNA
Explanation: During translation the initiation complex is formed between mRNA, the 30S ribosomal subunit and methionyl-tRNA. This complex is formed with the help of the initiation factors IF₁, IF₂ and IF₃ together with a GTP molecule.

Question 11

Previous-year question
Amino acid sequence, in protein synthesis, is decided by the sequence of [AIPMT 2006]
  1. tRNA
  2. mRNA
  3. cDNA
  4. rRNA
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Answer: (B) mRNA
Explanation: The messenger RNA carries the genetic code transcribed from DNA to the ribosome, where it is translated into protein. The sequence of amino acids in a particular protein is therefore determined by the sequence of nucleotides in the mRNA.

Question 12

Previous-year question
One gene-one enzyme hypothesis was postulated by [AIPMT 2006]
  1. R Franklin
  2. Hershey and Chase
  3. A Garrod
  4. Beadle and Tatum
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Answer: (D) Beadle and Tatum
Explanation: Beadle and Tatum (1941) gave the one gene-one enzyme hypothesis, stating that a particular gene controls the synthesis of a specific enzyme. It was later modified by Yanofsky et al. (1965) to the one gene-one polypeptide hypothesis.

Question 13

Previous-year question
One gene-one enzyme relationship was established for the first time in [AIPMT 2007]
  1. Neurospora crassa
  2. Salmonella typhimurium
  3. Escherichia coli
  4. Diplococcus pneumoniae
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Answer: (A) Neurospora crassa
Explanation: The one gene-one enzyme relationship was established by Beadle and Tatum on the basis of their experiments on the bread mould Neurospora crassa, for which they were awarded the Nobel Prize in 1958.

Question 14

Previous-year question
Which of the following rRNAs act as structural RNA as well as ribozyme in bacteria? [NEET 2016, Phase II]
  1. 5S rRNA
  2. 18S rRNA
  3. 23S rRNA
  4. 58S rRNA
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Answer: (C) 23S rRNA
Explanation: The 23S rRNA of bacteria has peptidyl transferase activity and catalyses peptide bond formation, making it the only known non-proteinaceous enzyme of translation. It also serves as a structural component of the large ribosomal subunit.

Question 15

Previous-year question
The first phase of translation is [NEET (Sep.) 2020]
  1. recognition of DNA molecule
  2. aminoacylation of tRNA
  3. recognition of an anti-codon
  4. binding of mRNA to ribosome
Show answer
Answer: (B) aminoacylation of tRNA
Explanation: The first phase of translation is the aminoacylation or charging of tRNA. In the presence of aminoacyl-tRNA synthetase and ATP, the amino acid is activated and attached to the 3'-CCA end of its specific tRNA.

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