Question

What is the function of enzyme ‘recombinase' during meiosis?
A)Formation of the synaptonemal complex
B)Crossing over between non-sister chromatids
C)Condensation of chromosomes
D)Alignment of the bivalent chromosome on the equatorial plane

Answer 1

Meiosis is the process of cell division which results in the production of male and female gametes in sexually reproducing organisms. In meiosis there are two stages, meiosis I and meiosis II.

Complete answer:
As a result of meiosis 4 daughter nuclei are formed. Unlike in mitosis, these daughter nuclei are not identical. The reason for this is during prophase I of meiosis, the chromosomes will condense and will pair up. The two homologous chromosomes with non-sister chromatids having different alleles will pair up. Between prophase I and metaphase I they will exchange chromosome segments with each other to form new recombinant chromosomes. This process is called crossing over in meiosis. This results in new allelic combinations in the offspring resulting in their distinguishing character.

Recombinase enzyme is a site-specific enzyme which helps in genetic recombination in the DNA. Now let’s analyse options to find out the function of the recombinase during meiosis.
Option A) Synaptonemal complexes are protein elements that form in between homologous chromosomes. Formation of this complex indicates the pairing of chromosomes. The recombinant enzyme does not play a role in the formation of this complex. Therefore, this is an incorrect option.
Option B) During the crossing over between non-sister chromatids, recombine enzymes will catalyse this reaction which results in the formation of new alleles. Therefore, this is the correct option.
Option C) Chromosomes condense during prophase I of meiosis. After that they will pair up to form homologous chromosomes. Recombinase enzymes do not help in this process. Therefore, this is an incorrect option.
Option D) bivalent chromosomes will align in the equatorial plane during metaphase I of meiosis. This process is also not catalysed by recombinase enzymes. Therefore, this is an incorrect option.

Hence, the correct answer is option (B)

Note: Recombinant enzymes are derived from bacteriophages and fungi. In general, they catalyse the exchange reaction between directionally sensitive DNA sequences between small target site sequences, which are specific to every recombinase. These sites of combination are called transposons.