Question

Enzyme involved in crossing over

• A. Lygase
• B. Recombinase
• C. Polymerase
• D. Endonuclease

Answer 1

The Correct Option is B

The correct answer is:

Option 2: Recombinase

Explanation:

Recombinase enzymes play a crucial role in the process of crossing over during meiosis. These enzymes facilitate the recombination of genetic material between homologous chromosomes by enabling the exchange of DNA segments.

Recombinase is involved in creating Holliday junctions, which are key intermediates in genetic recombination.

The other options are incorrect because:

Ligase (Option 1) is involved in joining DNA fragments but is not specifically involved in crossing over.

Polymerase (Option 3) synthesizes DNA but does not directly participate in the crossing-over process.

Endonuclease (Option 4) makes cuts in DNA, but it does not directly regulate the exchange of genetic material during crossing over.

Thus, recombinase is the enzyme involved in the crossing-over process.

Answer 2

Crossing over is a crucial process in meiosis where homologous chromosomes exchange genetic material, leading to genetic recombination.

To facilitate this exchange, specific enzymes are required:

• Ligase: Ligases join DNA fragments together by forming phosphodiester bonds. While important in DNA replication and repair, they are not directly involved in the cutting and exchange of DNA during crossing over.
• Recombinase: This is the correct answer. Recombinases are a class of enzymes that catalyze the exchange of DNA strands during genetic recombination. They are essential for the alignment of homologous chromosomes, strand invasion, and the formation of Holliday junctions, which are key intermediates in crossing over.
• Polymerase: Polymerases synthesize new DNA or RNA strands. They are vital for DNA replication and transcription but don't play a direct role in breaking and rejoining DNA during crossing over.
• Endonuclease: Endonucleases cleave phosphodiester bonds *within* a DNA strand. While they can initiate DNA breaks that lead to recombination, they do not, by themselves, facilitate the entire process of crossing over.

Therefore, the enzyme involved in crossing over is Recombinase.