Biology

DNA and Genetics

985 Questions

DNA and genetics questions explore molecular biology, DNA replication, and genetic engineering techniques. These topics are essential for various competitive exams requiring a strong foundation in life sciences. Practice these questions to understand complex biological processes thoroughly.

DNA replication mechanismsGenetic engineering techniquesGene editing toolsPolymerase chain reactionDNA sequencing methods

DNA and Genetics Questions

Multiple choice

During conjugation, the products of recA gene are required to

  1. facilitate the entry of donor DNA

  2. inherit the incoming genes by homologous recombination

  3. transfer the donor genes to the host DNA

  4. duplicate the DNA during the transfer
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Transfer of genes from a Hfr into a F-recipient cell (conjugation) requires the recA gene product because the incoming genes need to be inherited by homologous recombination.

Multiple choice

Distributive conjugal transfer is observed in

  1. Escherichia coli

  2. Mycobacterium smegmatis

  3. Agrobacterium

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

Distributive conjugal transfer takes place in Mycobacterium smegmatis. In Mycobacterium smegmatis, all regions of the chromosome are transferred with comparable efficiency.

Multiple choice

Which of the following statements regarding insertion sequences is false?

  1. They are capable of moving within a chromosome.

  2. They are capable of moving from one chromosome to another chromosome.

  3. They mediate site specific recombination.

  4. They are implicated in the evolution of R-plasmids.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is false. Insertion sequence elements appear to mediate recombination between non-homologous DNA molecules or sequences.

Multiple choice

The transfer of genes between bacteria by conjugation is known as

  1. vertical transfer

  2. lateral gene transfer

  3. horizontal gene transfer (HGT)

  4. sexual gene transfer
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The transfer of genes between bacteria by conjugation is known as horizontal gene transfer. It plays an important role in the evolution of bacteria that can degrade novel compounds.

Multiple choice

The filamentous bacteriophage containing circular single-stranded DNA is

  1. phage f1

  2. phage M13

  3. phage G4

  4. phage P4

  5. phage P2
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

M13 is a filamentous bacteriophage composed of circular single-stranded DNA (ssDNA) which is 6407 nucleotides long encapsulated in approximately 2700 copies of the major coat protein P8 and capped with 5 copies of two different minor coat proteins (P9, P6, P3) on the ends.

Multiple choice

The portion of DNA which contains information for an entire polypeptide is called

  1. cistron

  2. muton

  3. recon

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

A cistron is defined as the segment of DNA that contains the complete genetic information required to synthesize one polypeptide chain or functional RNA. Muton is the smallest mutable unit, recon is the smallest recombinable unit, and operon is a cluster of functionally related genes.

Multiple choice

Eukaryotic DNA replication is a conserved mechanism. Which of the following statements does NOT characterise the DNA replication?

  1. Each Okazaki fragment is preceded by an RNA dimer.

  2. The lagging strand usually contains longer stretches of single-stranded DNA.

  3. Okazaki fragments are formed on the lagging strand.

  4. Two replicative polymerases synthesise DNA in opposite orientations.

  5. Duplex DNA is always antiparallel.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Each Okazaki fragment is preceded by an RNA primer, which is displaced by the procession of the next Okazaki fragment during synthesis.