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 statements is not true regarding restriction enzymes?

  1. Inside a prokaryote, the restriction enzymes selectively cut up foreign DNA in a process called restriction.

  2. Restriction was first identified by Salvador Luria and Giuseppe Bertani in early 1950s.

  3. The restriction enzyme and the recognition sequence for Streptomyces albus are Sa-II and 5’ GTCGAC; 3’ CAGTCA respectively.

  4. The restriction enzymes studied by Arber and Meselson were type I restriction enzymes.

  5. Restriction endonuclease cuts DNA of bacteriophage in Escherichia coli.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The restriction enzyme and the recognition sequence for bacteria-Streptomyces albus are Sa-II and 5’ GTCGAC; 3’ CAGCTG respectively. 

Multiple choice

Which of the following combinations of ‘restriction enzyme: bacterial source-recognition sequence’ is not correctly matched?

  1. EcoR-I: Escherichia coli- 5’ GAATTC; 3’ CTTAAG

  2. EcoR-II: Escherichia coli- 5’ GATATC; 3’ CTATAG

  3. BamH-I: Bacillus amyloliquefaciens- 5’ GGATCC; 3’ CCTAGG

  4. Hind-III: Haemophilus influenzae- 5’ AAGCTT; 3’ TTCGAA

  5. Taq-I: Thermus aquaties- 5’ TCGA; 3’ AGCT
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The restriction enzyme for Escherichia coli is EcoR-II with recognition sequence of 5’ CCWGC; 3’ GCWCC. The restriction enzyme for Escherichia coli is EcoR-V with recognition sequence of 5’ GATATC; 3’ CTATAG.

Multiple choice

Identify the incorrect statement.

  1. Hetero-duplex is a double-stranded DNA molecule or DNA-RNA hybrid.

  2. In vitro synthesis of a gene of interest using two sets of primers and the enzyme DNA polymerase is called polymerase chain reaction.

  3. The coating of a protein that encloses the nucleic acid core of a virus is called capsid.

  4. Each of the two daughter strands of a duplicated chromosome joined at the centromere during mitosis and meiosis is called chromatid.

  5. The cutting of DNA by restriction endonuclease results in the fragments of DNA which has positive charge.
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

The cutting of DNA by restriction endonuclease results in the fragments of DNA. These fragments can be separated by a technique known as gel electrophoresis. DNA fragments are negatively charged molecules and can be separated by forcing them to move towards the anode under an electric field through a medium.

Multiple choice

Match the entries in group I with that in group II and select the correct answer.

 
Group I
Group II
P. Overlap-extension PCR 1. Splices together two or more DNA fragments that contain complementary sequences
Q. Hot start PCR 2. Reduces non-specific amplification during the initial set up stages of the PCR
R. Asymmetric PCR 3. Preferentially amplifies one DNA strand in a double-stranded DNA template
S. Digital PCR 4. Measures the quantity of a target DNA sequence in a DNA sample

  1. P - 1, Q - 2, R - 3, S - 4

  2. P - 1, Q - 3, R - 2, S - 4

  3. P - 2, Q - 1, R - 4, S - 3

  4. P - 2, Q - 3, R - 4, S - 1

  5. P - 4, Q - 3, R - 2, S - 1
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Overlap-extension PCR is a genetic engineering technique that is used to splice together two or more DNA fragments that contain complementary sequences. Hot start PCR is a technique that reduces non-specific amplification during the initial set up stages of the PCR. Asymmetric PCR preferentially amplifies one DNA strand in a double-stranded DNA template. Digital PCR is used to measure the quantity of a target DNA sequence in a DNA sample.

Multiple choice

Match the following:

 
Group I (Restriction Endonucleases)
Group II (Cleavage Position)
P. Type I enzymes 1. Cleave at sites remote from recognition site
Q. Type II enzymes 2. Cleave within or at short specific distances from recognition site
R. Type III enzymes 3. Cleave at sites a short distance from recognition site

  1. P - 2, Q - 1, R - 3

  2. P - 1, Q - 3, R - 2

  3. P - 1, Q - 2, R - 3

  4. P - 3, Q - 2, R - 1

  5. P - 2, Q - 3, R - 1
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Restriction endonucleases are enzymes that cut DNA at or near specific recognition nucleotide sequences known as restriction sites. Type I restriction enzymes cleave at sites remote from recognition site. Type II restriction enzymes cleave within or at short specific distances from recognition site. Type III restriction enzymes cleave at sites a short distance from recognition site.

Multiple choice

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

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. If A and R both are correct and R is correct explanation of A.
2. If A and R both are correct and R is not correct explanation of A.
3. If A is correct and R is incorrect.
4. If A is incorrect and R is correct.
5. If A and R both are incorrect.

  1. 1

  2. 2

  3. 3

  4. 4

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

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 recognise between 9 and 18 base pairs.

Multiple choice

The enzyme that joins DNA fragments is:

  1. restriction endonuclease

  2. lipase

  3. peroxidase

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

DNA ligase catalyzes the formation of phosphodiester bonds between DNA fragments, essential for joining DNA pieces in genetic engineering and replication. Restriction enzymes cut DNA, while lipase and peroxidase act on lipids and peroxides respectively, not nucleic acids.

Multiple choice

Assertion (A): Lysozyme is an antibacterial enzyme. Reason (R): The enzyme lysozyme kills bacteria by hydrolysing the (β1 → 4) glycosidic bond between N-acetylglucosamine and N-acetylmuramic acid.

Directions: In the following question, there are two statements: Assertion (A) and Reason (R). Consider both the statements independently and mark your answer as  

1. if A and R both are correct and R is correct explanation of A 
2. if A and R both are correct and R is not correct explanation of A 
3. if A is correct and R is incorrect 
4. if A is incorrect and R is correct 
5. if A and R both are incorrect

  1. 1

  2. 2

  3. 3

  4. 4

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

Both assertion and reason statements are correct.

Multiple choice

Genophore refers to

  1. prokaryotic nucleus

  2. chromosome of the prokaryotes

  3. genome of the eukaryote

  4. nucleosome of the eukaryotes

  5. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Genophore is the chromosome equivalent in viruses, prokaryotes and certain organelles.

Multiple choice

Plasmids occur in :

  1. viruses

  2. chromosomes

  3. bacteria

  4. chloroplasts

  5. fungi
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Plasmids are extra chromosomal DNA found in bacteria.

Multiple choice

Phenotypically silent DNA sequences that are not expressed during life cycle of an organism are called:

  1. Cryptic genes

  2. Split genes

  3. Constitutive genes

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

Cryptic genes are DNA sequences that exist in the genome but are not expressed during the normal life cycle of an organism. Split genes contain introns and exons, constitutive genes are always expressed, and pseudogenes are non-functional copies of genes that lost their protein-coding ability.

Multiple choice

The yeast most commonly used for protein expression using recombinant DNA techniques in different organisms is

  1. Candida guilliermondii

  2. Pichia methanolica

  3. Pichia pastoris

  4. Pichia stipitis

  5. Fleischmann’s Yeast
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Pichia pastoris is a species of methylotrophic yeast. Pichia is widely used for protein expression using recombinant DNA techniques. Hence, it is used in biochemical and genetic research in academia and the biotechnical industry.

Multiple choice

Which of the following enzymes can join the broken ends of two DNA strands?

  1. Ligase

  2. Lipase

  3. Polymerase

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

DNA ligase is the enzyme responsible for joining DNA strands by forming phosphodiester bonds between nucleotides. It plays a crucial role in DNA replication and repair processes. Ligase literally means 'to bind' or 'to join,' which is exactly its function in molecular biology.