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

The TATA box is located in the

  1. alternative acceptor site

  2. alternative donor site

  3. promoter

  4. intron-exon border
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

TATA box is located in the promoter and is involved in gene regulation.

Multiple choice

The anticodon sequence is found on

  1. transfer RNA

  2. messenger RNA

  3. ribosomal RNA

  4. complementary RNA (cRNA)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The anticodon is present on the tRNA and recognizes the codon sequence on the mRNA.

Multiple choice

What is the role of reverse transcriptase in eukaryotic cell?

  1. DNA repair

  2. Transcription

  3. Gene regulation

  4. DNA replication

  5. Translation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It is also known as RNA dependent DNA polymerase. It is a DNA polymerase that transcribes single stranded RNA into single stranded DNA. It is also a DNA dependent DNA polymerase, which synthesizes a second strand of DNA complementary to the c-DNA. In eukaryotic cell, telomerase is an example of reverse transcriptase.

Multiple choice

5' capping in m-RNA in eukaryotes is required for

  1. initiation of transcription

  2. initiation of translation

  3. initiation of replication

  4. removal of intron

  5. binding of exons together
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

5' capping protects messenger RNA and provides stability, which is able to undergo translation.

Multiple choice

The function of the nucleolus in the cell is

  1. Initiates and regulates cell division

  2. Synthesis of DNA

  3. Synthesis of RNA and ribosomes

  4. Intracellular digetion

  5. Carry hereditary structures
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Nucleolus produces ribosomes participates in protein synthesis by forming and storing RNA.

Multiple choice

The Mendelian “factors” are now known as __________.

  1. genes

  2. chromosome

  3. DNA

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

Mendel's 'factors' are the discrete units of heredity he proposed, which were later discovered to be genes - segments of DNA that code for specific traits. Chromosomes and DNA are the structures that contain genes, while genes are the functional units.

Multiple choice

__________ provides the information for synthesis of enzymes.

  1. Chromatin

  2. Gene

  3. Chromosome

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

Genes are segments of DNA that contain the instructions for making specific proteins, including enzymes. Each gene carries the genetic code in its sequence of nucleotides, which is transcribed and translated to produce the corresponding enzyme. Chromatin and chromosomes are structural components that contain genes, while the nucleus is the cellular compartment where this genetic material is housed.

Multiple choice

The function of tRNA is to

  1. transport specific amino acid to specific sites on the mRNA

  2. from a site for protein synthesis

  3. synthesize amino acids

  4. transcribe the genetic code

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

tRNA (transfer RNA) molecules serve as adaptor molecules that carry specific amino acids to the ribosome. Each tRNA recognizes a specific codon on the mRNA through its anticodon sequence, ensuring the correct amino acid is added to the growing polypeptide chain in the order specified by the mRNA.

Multiple choice

The ras oncogene contribute to the development of cancers by which of the following?

  1. Coding for an anti-apoptotic protein in the cell.

  2. Coding for an enzyme known as GTPase switch protein, which cannot be turn off in its mutated form.

  3. Coding Ras gene products which are involved in lipid signaling pathways.

  4. Coding for a transcription factor, being synthesised in enormous amount in the body.

  5. Coding for a abbreviated form of a growth factor receptor which is continually active.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The ras gene codes for a GTPase switch protein, which forms part of a growth factor signalling pathway. Stimulation of this protein via an occupied growth factor receptor causes it to activate by exchanging a molecule of GDP for GTP. The activated ras protein then activates downstream proteins, which ultimately activate transcription factors. Normally the ras signal is self limiting because the protein has intrinsic GTPase activity, so it hydrolyses its bound GTP to GDP, switching the signal off.

Multiple choice

The number of RNA molecules in 60S subparticles of 80S ribosomes are

  1. 5

  2. 4

  3. 3

  4. 2
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Eukaryotic 80S ribosomes consist of a 60S large subunit and a 40S small subunit. The 60S subunit contains three rRNA molecules: 28S, 5.8S, and 5S, while the 40S subunit contains only one 18S rRNA. This is different from prokaryotic 70S ribosomes which have only 2 rRNA molecules total.

Multiple choice

Which of the following viruses contains double-stranded RNA?

  1. Reoviridae

  2. Picornaviruses

  3. Togaviruses

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

Reoviridae is the only virus family listed that contains double-stranded RNA as its genetic material. The name 'Reovirus' actually stands for Respiratory Enteric Orphan virus. Picornaviruses, Togaviruses, and Coronaviruses all contain single-stranded RNA genomes.