Question

Does interphase occur between telophase I and prophase II of meiosis? If interphase did occur between the stages, what would the result be for the end of meiosis?? (Hint – think back to G1, S, and G2…what happens in each of those that you would or would NOT want to happen)

Discuss crossing over (homologous recombination). Which stage of meiosis does this occur in? What are the benefits to this process?

Answer 1

Interphase or interkinesis occurs between the first nad second meiotic divisions. The second meiotic division is actually mitosis , haploid cells from 1st division (n chromosomes) perform equitional division to form four cells with n chromosomes. So interphase occurs between telophase I and prophase II.

Due to presense of interphase in between telophase I and prophase II , the two n cells resulted from haploid division of diploid 2n cells gather energy , snythesize DNA and protein to perform mitosis. At the end of meiosis there results four cells with n number of chromosomes. In G1,S, and G2 phase active RNA , DNA and protein synthesis occurs which is required here , but cellular growth is not that important.

Crossing over occurs in Prophase I pachytene or pachynema stage. in this stage the paired chromosomes of each bivalent gets shortened and thickened and are prominently visible.

Crossing over is a process by which exchange of genetic matter takes place between two non sister homologous chromatids before meiosis. The homologous pairs of chromosomes from both parents gather together. Two chromatids from each chromosomes cross each other to form a X- shaped structure called chiasmata.The parts from each chromatid in the X is cut by by enzyme endonuclease. Each cut part joins the opposite chromosome. The joining is done by enzyme ligase. Thus two homologous chromosomes has a little part of each other. Thus paternal and maternal characteristics are mixed before sexual reproduction. This results in transfer of characteristics and variation.