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 types of mutagenesis is used to introduce multiple mutations into the DNA sequence?

  1. Directed Mutagenesis

  2. Random Mutagenesis

  3. Mismatched Mutagenesis

  4. Cassette Mutagenesis

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

Is used to introduce multiple mutations into the DNA sequence. Using blunt ended DNA at the site of mutation, a 3 base pair direct terminal repeat is created. The mutagenic codon cassette has a head to head SAPL site to remove all the DNA except the mutated one.

Multiple choice

Different steps of Variable Number of Tandem Repeats (VNTR) technique are given below: (i) Isolation of DNA, (ii) Separation of DNA fragments by electrophoresis (iii) Digestion of DNA by restriction endonucleases (iv) Hybridisation using labelled VNTR probe (v) Transferring (blotting) of separated DNA fragments to synthetic membranes, such as nitrocellulose or nylon (vi) Detection of hybridised DNA fragments by autoradiography.

The first and the last steps are placed correctly. Which one of the following arrangements of steps (ii) to (v) is correct?

  1. (ii) → (iii) → (iv) → (v)

  2. (iii) → (ii) → (iv) → (v)

  3. (iii) → (ii) → (v) → (iv)

  4. (ii) → (iii) → (v) → (iv)

  5. (ii) → (iv) → (iii) → (v)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Correct order of various steps of Variable Number of Tandem Repeats (VNTR) technique is: (i) → (iii) → (ii) → (v) → (iv) → (vi) Isolation of DNA → digestion of DNA by restriction endonucleases → separation of DNA fragments by electrophoresis → transferring (blotting) of separated DNA fragments to synthetic membranes, such as nitrocellulose or nylon → hybridisation using labelled VNTR probe → detection of hybridised DNA fragments by autoradiography.

Multiple choice

Assertion: Zinc-finger nucleases (ZFNs) are artificial restriction enzymes. Reason: The DNA-binding domains of individual ZFNs typically contain between nine and eighteen individual zinc finger repeats.

  1. A and R both are correct and R is correct explanation of A.

  2. A and R both are correct and R is not correct explanation of A.

  3. A is correct and R is incorrect.

  4. A is incorrect and R is correct.

  5. A and R both are incorrect.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Yes, it is the correct answer. A is correct whereas R is incorrect Zinc-finger nucleases are artificial restriction enzymes obtained by fusing a zinc finger DNA-binding domain to a DNA-cleavage domain. The DNA-binding domains of individual ZFNs typically contain between three and six individual zinc finger repeats and can each recognize between 9 and 18 base pairs.  

Multiple choice

Assertion: The normal role of restriction endonucleases in the bacterial cells is to degrade invading phage DNA. Reason: Bacterial cells protect their own DNA from degradation by restriction endonucleases by methylating the DNA at the sites that the enzyme recognizes.

Directions: In the following question there are two statements, Assertion (A) and Reason (R), consider both the statements independently and mark your answers as under:
1. A and R both are correct and R is correct explanation of A.
2. A and R both are correct and R is not correct explanation of A.
3. A is correct and R is incorrect.
4. A is incorrect and R is correct.
5. A and R both are incorrect.

  1. A and R both are correct and R is the correct explanation of A.

  2. A and R both are correct and R is not the correct explanation of A.

  3. A is correct and R is incorrect.

  4. A is incorrect and R is correct.

  5. A and R both are incorrect.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The normal role of restriction endonucleases in bacterial cells to degrade invading phage DNA because bacterial cells protect their own DNA from degradation by restriction endonucleases by methylating the DNA at the sites that the enzyme recognizes. Thus, this option is correct.

Multiple choice

What is the composition of type II restriction endonuclease?

  1. It is a three-subunit enzyme with endonuclease and methylase activities.

  2. It is a single subunit enzyme in which endonuclease and methylase are seperate.

  3. It is a two subunit complexes, in which endonuclease and methylase are seperate.

  4. It is a two subunit enzyme, with endonuclease and methylase actiivities.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This enzyme is very much useful to recombinant DNA researches than the other two types.

Multiple choice

Restriction endonuclease is used in

  1. Regeneration of tissues

  2. Cell fractionation

  3. Tissue culture

  4. Genetic engineering
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

There are three general types of restriction enzymes type I and III cleave DNA away from recognition sites. Type II restriction endonucleases DNA at specific recognition sites.

Multiple choice

Which one of the following statements is true?

P. Enzyme required for removing RNA primer during DNA replication is DNA primase. Q. The enzyme DNA polymerase can work only in 3’→5’ direction. R. The enzyme that cuts the bonds of DNA molecule at the origin of replication is restriction endonuclease. S. The enzyme required to release the tension imposed by uncoiling of strands is DNA gyrase.

Select the correct answer using codes given below:

  1. P and Q

  2. P and S

  3. Q and R

  4. Q and S

  5. R and S
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The enzyme that cuts the bonds of DNA molecule at the origin of replication is restriction endonuclease. The enzyme required to release the tension imposed by uncoiling of strands is DNA gyrase.

Multiple choice

Which of the following statements is false?

P. The first enzyme molecule to be isolated in pure crystalline form was alkaline protease. Q. Synthesis of enzymes is regulated by inducer and repressor genes. R. DNA ligase is first isolated from bacteriophages. S. Ribozyme is RNA with enzyme activity.

Select the correct answer using codes given below:

  1. P and Q

  2. P and R

  3. P and S

  4. Q and R

  5. R and S
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The first enzyme molecule to be isolated in pure crystalline form was urease, prepared from the jack bean in 1926 by American biochemist J. B. Sumner. Synthesis of enzymes is regulated by operator and regulator genes.

Multiple choice

Which of the following statements are false?

P. Plasmids are circular pieces of double stranded DNA that exist separately from chromosomal DNA. Q. Plasmids that can be propagated in cells of two or more different species are called expression vectors. R. Shuttle vectors cannot be used in prokaryotes. S. A cloning vector is a small piece of DNA into which a foreign DNA fragment can be inserted for cloning purposes.

Select the correct answer using codes given below:

  1. P and Q

  2. P and S

  3. Q and R

  4. Q and S

  5. R and S
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Plasmids that can be propagated in cells of two or more different species are called shuttle vectors. An expression vector is generally a plasmid that is used to introduce a specific gene into a target cell. A shuttle vector is a vector that can propagate in two different host species; hence, inserted DNA can be tested or manipulated in two different cell types. It can be used in both eukaryotes as well as prokaryotes.