Biology

Molecular Genetics

851 Questions

Molecular genetics explores the mechanisms of genetic information transfer, including DNA replication, transcription, and translation. It is a core component of biology syllabi. These concepts frequently appear in general science sections of major competitive exams.

DNA replicationTranscription processTranslation processRNA typesCentral dogma

Molecular Genetics Questions

Multiple choice

Which of the following is the sequence of m-RNA?

  1. 3’-TACGTACGTACGTACG-5’

  2. 3’-UACGUACGUACGUACG-5’

  3. 3’-AUGCAUGCAUGCAUGC-5’

  4. 5’-ATGCATGCATGCATGC-3’

  5. 5’-AUGCAUGCAUGCAUGC-3’
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

First we reduce the template strand sequence from the coding strand as follows 3’-TACGTACGTACGTACG-5’. Now, the RNA strand will be complimentary to this with U replacing T as follows 5’-AUGCAUGCAUGCAUGC-3’

Multiple choice

What are polyribosomes?

  1. Cluster of ribosomes bound to t RNA

  2. Cluster of ribosomes bound to r RNA

  3. Cluster of ribosomes bound to m RNA

  4. Cluster of ribosomes bound to proteins
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Polyribosomes are a cluster of ribosomes bound to mRNA molecule in the act of protein synthesis.

Multiple choice

Nonsense codons are present in

  1. t-RNA

  2. m-RNA

  3. Ribosomal RNA

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Some codons signify termination of the amino acid chain. These are called nonsense codons. UAG, UAA and UGA respectively known as amber, ochre and opal.

Multiple choice

Which of the following statements is/are false?

  1. The start codon always codes for methionine in eukaryotes.
  2. The anticodon is a sequence of three base pairs of the tRNA that is complementary to the matching three base pairs on the mRNA.
  3. The termination codon is a nucleotide triplet within tRNA that signals termination of translation.

Select the correct answer using codes given below:

  1. 1 only

  2. 2 only

  3. 3 only

  4. 1 and 2

  5. 2 and 3
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The stop codon or termination codon is a nucleotide triplet within mRNA that signals a termination of translation.

Multiple choice

In which of the following processes a complementary RNA copy of a sequence of DNA is created?

  1. Translation

  2. Transcription

  3. DNA condensation

  4. Gene regulation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Transcription is the process of creating a complementary RNA copy of a sequence of DNA.Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes.

Multiple choice

Formation of mRNA from DNA is

  1. translation

  2. transcription

  3. transformation

  4. transduction

  5. -
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Transcription is the first step of gene expression, in which a particular segment of DNA is copied into RNA (mRNA) by the enzyme RNA polymerase.

Multiple choice

The function of polymerase chain reaction is

  1. transduction

  2. DNA amplification

  3. translation

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The polymerase chain reaction (PCR) is a technique that is used in molecular biology to amplify a single copy or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence.

Multiple choice

Post - transcriptional regulation includes

  1. binding of repressor on silencer regions

  2. transport of messenger RNA into the cytoplasm

  3. decreasing messenger RNA stability in the cytoplasm

  4. Both (b) and (c)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

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Multiple choice

A functional piece of mRNA has 66 codons. What is the maximum number of amino acids that could be present in the protein coded for by this mRNA?

  1. 22

  2. 64

  3. 65

  4. 66
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A functional strand of mRNA must have a start and a stop codon. The start codon often also codes for the amino acid methionine, which may or may not end up being a part of the final protein. However, the stop codon would not code for an amino acid. Thus, with 66 codons in the mRNA, there could be as many as 65 amino cells in the protein product.