Question

Short / Long Answer Type Questions :
Draw and explain a series of diagrams that illustrate the stages of meiosis I.

Answer 1

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At the onset of meiosis, DNA strands thicken into chromosomes.

Homologous, or like chromosomes begin to approach each other.

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Homologous chromosomes pair to from bivalents.

The centrioles divide and move to opposite poles of the cell.

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The bivalents duplicates to from tetrads, or four-chromatid groups.

The nuclear membrane disntegrates.

Crossing over (recombination) occurs.

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In metaphase I, the tetrads, attached to spindle fibers at their centromere, line up at mid-cell.

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In early anaphase I, the tetrads separate, and the paired chromatids move along the spindle to their respective centrioles.

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In late anaphase I, the chromatides have almost reached the spindle poles. The cell membrane begins to constrict.

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In telophase I, nuclear membrans enclose the sparated chromatids.

The cell membrane completes its constriction.

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The first meiotic division ends.

There are now two cells each with the same number of

chromatids as the parent cell.