Biology

DNA and Genetics

1,095 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

Which of the following are examples of DNA and protein sequence alignment programs?

  1. ClustalW2
  2. FASTA
  3. Melanie
  4. PROSITE

  1. 1 and 2

  2. 1 and 3

  3. 1 and 4

  4. 2 and 3

  5. 2 and 4
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Correct answer. ClustalW2 is a general purpose multiple sequence alignment program for DNA or proteins. PROSITE is a protein database consisting of entries describing the protein families, domains and functional sites as well as amino acid patterns and profiles in them.

Multiple choice

Which technique is used to detect auxotrophic mutants?

  1. Replica plating

  2. Ames test

  3. Carcinogenicity testing

  4. Shotgun sequencing

  5. Chromosome walking
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A strain is said to be auxotrophic if it carries a mutation that renders it unable to synthesize an essential compound. This technique distinguishes between mutants and the wild type strain based on their ability to grow in the absence of a particular biosynthetic end product. For example a lysine auxotroph will grow on lysine supplemented media but not on a medium lacking an adequate supply of lysine because it cannot synthesize this amino acid.

Multiple choice

Which type of mutation can be expressed through the example given in the passage?

A mutation in the Escherichia coli bacteria might not be expressed under permissive conditions such as low temperature but could be expressed under restrictive conditions such as high temperature.

  1. Lethal mutation

  2. Conditional mutation

  3. Adaptive mutation

  4. Somatic hypermutation

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

Conditional mutation is a mutation that has wild type or less severe phenotype under certain permissive environmental conditions and a mutant phenotype under certain restrictive conditions. For example a temperature sensitive mutation can cause cell death at high temperature (restrictive condition) but might have no deleterious consequences at a lower temperature (permissive condition).

Multiple choice

A proto-oncogene is described as DNA that

  1. causes cancer

  2. causes the vascularization of a tumour

  3. can be mutated into cancer causing DNA

  4. directly causes uncontrolled cellular growth
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A proto-oncogene is a normal body gene, which becomes an oncogene due to mutations or increased expression. They code for proteins controlling cell growth and differentiation.

Multiple choice

Which one of the following is also known as southern hybridization ?

  1. DNA-RNA hybridization

  2. RNA-DNA hybridization

  3. DNA-DNA hybridization

  4. Protein-Protein hybridization
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Southern hybridization is a technique where DNA is transferred from a gel to a membrane and probed with complementary DNA sequences, making it DNA-DNA hybridization. The technique is named after Edwin Southern, while Northern (RNA-RNA) and Western (protein-protein) are other related techniques.

Multiple choice

The plasmid derived from E.coli plasmid Col E1 is

  1. YIP

  2. pYAC

  3. pBR-322

  4. Ti-plasmid
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

pBR-322 was one of the first widely used cloning vectors and was derived from E. coli plasmid Col E1. It contains antibiotic resistance genes (ampicillin and tetracycline) and multiple cloning sites, making it ideal for recombinant DNA work.

Multiple choice

With reference to the designing of vectors based on Ti and Ri plasmids, consider the following statements:

  1. They are disarmed by removing the genes causing the disease.

  2. They carry sites for insertion of gene of interest.

  3. They carry selectable markers.

Which of the statements given above are correct?

  1. 1 and 2 only

  2. 2 and 3 only

  3. 1 and 3 only

  4. 1,2 and 3
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Ti (tumor-inducing) and Ri (root-inducing) plasmids are disarmed by removing disease-causing genes while retaining the T-DNA region for gene insertion. They include selectable markers (antibiotic resistance) and cloning sites for genetic engineering. All three statements correctly describe vector design.

Multiple choice

Assertion (A) : The rate of DNA replication is much faster in E. coli than in eukaryotes.

Reason (R) : The length of Okazaki fragments that result from DNA Polymerase I activity are much shorter in prokaryotes than in eukaryotes.

  1. Both A and R are individually true and R is the correct explanation of A.

  2. Both A and R are individually true but R is not the correct explanation of A.

  3. A is true but R is false.

  4. A is false but R is true.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

It is true that the rate of DNA replication is much faster in E. coli than in eukaryotes. It is also true that the length of Okazaki fragments that result from DNA Polymerase I activity are much shorter in prokaryotes than in eukaryotes. But R is not the correct explanation of A.