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

Which of the following technique is used to detect methylation of DNA?

  1. Western blotting

  2. Souther blotting

  3. Northern blotting

  4. Bisulfide blotting

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

Treatment of DNA with bisulfite converts cytosine residues to uracil, but leaves 5-methylcytosine residues unaffected.Thus, bisulfite treatment introduces specific changes in the DNA sequence that depend on the methylation status of individual cytosine residues.

Multiple choice

Which one is required for protoplast fusion?

  1. Treatment. with cellulase and pectinase

  2. Electrofusion or PEG treatment

  3. Both A and B

  4. Recombinant DNA technology
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The somatic (protoplast) fusion process occurs in four steps:1. The removal of the cell wall of one cell of each type of plant using cellulase enzyme to produce a somatic cell called a protoplast2. The cells are then fused using either an electric shock (electrofusion) to join the cells and the nuclei fused together or by chemicaltreatment. The resulting fused nucleus is called heterokaryon.3. The somatic hybrid cell then has its cell wall induced to form using hormones4. The cells are then grown into calluses which then are further grown to plantlets and finally to a full plant, known as a somatic hybrid.

Multiple choice

The enzymes which are commonly used in genetic engineering are

  1. restriction endonuclease and polymerase

  2. endonuclease and ligase

  3. restriction endonuclease and ligase

  4. ligase and polymerase
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Restriction enzymes, also known as restriction endonucleases, are enzymes that cut a DNA molecule at a particular place.

Multiple choice

Restriction enzymes are used in genetic engineering because they

  1. Can join DNA fragments

  2. Cut DNA at specific base sequence

  3. Cut DNA at variable sites

  4. Are proteolytic enzymes which degrade harmful proteins
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A restriction enzyme (or restriction endonuclease) is an enzyme that cuts DNA at or near specific recognition nucleotide sequences known as restriction sites

Multiple choice

The primase is used in DNA replication for

  1. joining okazaki fragments

  2. the formation of new DNA

  3. the synthesis of DNA primer

  4. the synthesis of RNA primer
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The primase is used for DNA replication as it helps in the synthesis of RNA primer.

Multiple choice

The role of enzyme DNA ligase in DNA replication is

  1. to add more nucleotides to the growing strand one at a time

  2. to open up the two DNA strands to expose template strands

  3. to remove incorrectly matched bases

  4. to join okazaki fragments to one another
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The role of enzyme DNA ligase in DNA replication is to bond okazaki fragments to one another.

Multiple choice

In semiconservative replication of DNA,

  1. the original double helix remains intact and a new double helix forms

  2. the strands of the double helix seperate and act as templates for new strands

  3. polymerisation is catalysed by RNA polymerase

  4. polymerisation is catalysed by DNA ligase enzyme
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In semiconservative replication of DNA, the strands of the double helix seperate and act as templates for new strands.

Multiple choice

Okazaki fragments are

  1. short DNA fragments on the lagging strand

  2. short DNA fragments on the leading strand

  3. RNA primers required for initiation of DNA synthesis

  4. DNA fragments produced due to radiation action
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Okazaki fragments are short DNA fragments on the lagging strand. Synthesis of the lagging strand requires working in relatively small, discontinuous stretches. These discontinuous stretches are synthesised just as the leading strand, by the addition of new nucleotides one at a time to the 3′ end of the new strand, but the synthesis of this new strand moves in the direction opposite to that in which the replication fork is moving. These stretches of new DNA for the lagging strand are called Okazaki fragments.