Question

In meiosis, why do chromosomes first become visible through a compound microscope in the first stage of Prophase I?

Answer 1

Meosis is the part of cell cycle. Meosis occurs in the sperm and egg cell. In meosis the diploid cell divide and produce haploid cells.

Meosis can be divided into 5 stages viz prophase , metaphase ,anaphase ,tellophase, and cytokinesis.

Prophase I is the first stage of meosis and it is divided into 5 further stages leptotin , zygotene,pachytene ,diplotene and diakinesis.

In leptotin the neucleus becomes bigger and the chromosomes can be visible like thin ware.

In zygotene the attraction between two homologous chromosome is stronger and as a result they come closer to each other. Synaptonemal complex helps these chromosome to fuse together. These fused chromosome then become shorter and denser.

In pachytene phase, crossing over occurs between the non sister chromatid and genetic information transfered.

In diplotene the attraction is weak so the chromosome becomes separated from each other.

In diakenesis the chromosome becomes short and more dennced and the nucleolous and nuclear membrane disappeared completely.

During prophase 1 the cromosome in nucleus become more short and denced and at the end of prophase the nuclear membrane compltely disappeared. This is the reason that we can see the chromosome in prophase 1 by compound microscope.