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

Which statement is not true regarding translation machinery?

  1. Anticodon consists of three nucleotides.

  2. Anticodon may pair with more than one codon.

  3. It is the basic unit of genetic code.

  4. tRNA is an adaptor molecule composed of RNA, typically 76 to 90 nucleotides in length.

  5. The covalent attachment to the tRNA 3’ end is catalyzed by enzymes called aminoacyl tRNA synthetases.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This statement is not true as codon, which is a sequence of three nucleotides on m-RNA, is the basic unit of genetic code.

Multiple choice

The introduction of DNA has developed tobacco plants resistant to nematodes. The DNA in the host cell produces which of the following?

  1. Both sense and antisense RNA

  2. A particular hormone

  3. An antifeedeant

  4. A toxic protein
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Antisense RNA  is a single-stranded RNA which is complementary to a messenger RNA strand transcribed within a cell. In tobacco plants resistant to nematodes, the DNA produces both sense and antisense RNA.

Multiple choice

The 3' end of most mRNA's have

  1. poly G tail

  2. poly A tail

  3. poly C tail

  4. poly U tail
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The 3' end of most mRNA's has a poly A tail. It prevents the attack by 3' exonucleases.

Multiple choice

Which of the following is the immediate precursor of mRNA?

  1. A single strand of DNA

  2. Heterogeneous nuclear RNA

  3. rRNA

  4. Small interfering RNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Heterogeneous nuclear RNA acts as immediate precursor for synthesis of mRNA. Mature mRNA is formed from hnRNA by capping, tailing, splicing and base modification.

Multiple choice

Which of the following is a clover leaf-like structure?

  1. Primary structure of tRNA

  2. Secondary structure of tRNA

  3. Tertiary structure of tRNA

  4. Denatured tRNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Each single tRNA shows extensive internal base pairing and acquires a clover leaf-like structure. The structure is stabilised by hydrogen bonding between the bases and is a consistent feature.