Biology

Molecular Genetics

917 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

Directions: The following question has four choices out of which ONLY ONE is correct.

What is antisense technology?

  1. RNA polymerase producing DNA

  2. A cell displaying a foreign antigen used for synthesis of antigens

  3. Production of somaclonal variants in tissue cultures

  4. When a piece of RNA that is complementary in sequence is used to stop expression of a specific gene
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

 When a piece of RNA that is complementary in sequence is used to stop expression of a specific gene is antisense technology.

Multiple choice

RNA retroviruses have a special enzyme that

  1. translates host DNA

  2. disintegrates host DNA

  3. polymerizes host DNA

  4. transcribes viral RNA to c-DNA
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Retroviruses have an enzyme reverse transciptase, which has the ability to transcribe viral RNA to a complementary DNA strand. The process is also called teminism as its discoverers are Temin and Baltimore.

Multiple choice

DNA generally acts as a template for the synthesis of

  1. protein only

  2. DNA only

  3. RNA only

  4. RNA and DNA both
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

DNA generally acts as a template for the synthesis of DNA during replication and RNA during transcription. DNA does not act as a template for the synthesis of protein.

Multiple choice

What is replicated in semi-conservative process?

  1. mRNA only

  2. DNA only

  3. mRNA and tRNA only

  4. mRNA, tRNA and DNA only
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Semi-conservative model replicates DNA only as DNA has two strands which can act template for synthesis of new DNA.

Multiple choice

Transcription occurs in ___________.

  1. heterochromatin

  2. euchromatin

  3. nuclear envelope

  4. nuclear pore

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

Euchromatin participates in the active transcription of DNA to mRNA products.

Multiple choice

Which among the following explanations regarding the proto-oncogenes is NOT true?

  1. These genes are produced by somatic mutations induced by carcinogenic substances.

  2. These genes also code for proteins associated with cell growth.

  3. Some are activated by gene amplification.

  4. They are originally derived from RNA tumor viruses.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It is a normal gene that can become an oncogene due to mutations or increased expression. They are derived from RNA tumor viruses.

Multiple choice

Which among the following is the 3' end of the tRNA?

  1. Carrier end

  2. Recognition end

  3. Enzyme site

  4. Ribosome site
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

It is described as the 3' end of the tRNA. Here a particular amino acid gets associated. The tRNA molecule has a base triplet CCA with OH group at the tip. The COOH of amino acid conjoins the OH group.

Multiple choice

Which among the following reaction is catalyzed by aminoacyl tRNA synthetase enzyme?

  1. Activation of amino acids

  2. Charging of tRNA

  3. Activation of ribosome

  4. Polysome formation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

It is defined as the step where the amino acid AMP-enzyme complex conjoins with the amino acid binding site of its specific tRNA, where its COOH group bonds with the OH group of the terminal base triplet CCA. This reaction is catalyzed by the same enzyme, aminoacyl tRNA synthetase.

Multiple choice

In a virus, the RNA genome covering protein is

  1. G protein

  2. M protein

  3. L protein

  4. N protein

  5. Gag-onc fusion protein
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This is the major structural protein and covers the RNA genome. It protects the genome from nucleases and holds it in a conformation that allows transcription.

Multiple choice

Which among the following statements characterises an oncogene?

  1. It codes for a cell cycle control protein in a cell.

  2. It codes for a protein which restricts the cell from apoptosis.

  3. It codes for a mutated form of a protein which creates fractions of a signal transduction pathway.

  4. Many cancer drugs target the proteins encoded by oncogenes.

  5. It is a predominantly expressed mutation providing a cell a growth or survival advantage.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

An oncogene is a mutated form of a normal cellular gene (the proto-oncogene) which codes for a protein which is either controlled abnormally so that it is expressed in abnormally large amounts or has gained activity so that it is more active than the normal protein.