Q27 / 180 · NEET 2014 · Botany

The enzyme recombinase is required at which stage of meiosis:

  • Correct answer
    A
    Pachytene
  • B
    Zygotene
  • C
    Diplotene
  • D
    Diakinesis

Solution

The characters of Pachytene/Pachynema are as follows-
  1. Crossing over i.e. exchange of segments between non-sister chromatids of homologous chromosome occurs at this stage.
  2. Chromatids of pachytene chromosome are attached with centromere. 
  3. A tetrad consists of two sets of homologous chromosomes each with two chromatids. Each tetrad has four kinetochore (two sister and two homologous). 
  4. A number of electron dense bodies about 100 nm in diameter are seen at irregular intervals within the centre of the synaptonemal complex, known as recombination nodules.
  5. Enzyme recombinase is responsible for causing crossing over.
  6. Crossing over leads to recombination of genes and hence, variations.

Hence, the correct answer is option: 'A'.

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