Cell Cycle and Cell Division Test - 7

Small disc-shaped structures at the surface of the centromeres are called kinetochores. These structures serve as the sites of attachment of spindle fibres (formed by the spindle fibres) to the chromosomes.

During anaphase stage, metaphase plate splits and each chromosome moves away from equatorial plane splitting the centromere and separate chromatids which move to opposite poles.

Meiosis cell division results in halving of chromosome number in daughter cells, recombination of genes and formation of spores and gametes.

In telophase I, the nuclear membrane and nucleolus reappear indicating the process of completion od nuclear division . Meiosis II is similar to mitosis.

Synapsis occur between two homologous chromosome during zygotene phase of prophase of meiosis I due to presence of synaptonemal complex between homologous chromosomes.

In oocytes of some vertebrates, diplotene can last for months or years.Such nucleus showing arrested diplotene stage is called mesokaryotic nucleus.

The stage between the two meiotic divisions is called interkinesis and is generally short lived. Interkinesis is followed by prophase II, a much simpler prophase than prophase I.

Crossing over occurs in pachytene sub-stage of prophase of meiosis I. During which exchange of genetic materials takes place between homologous chromosomes.

If a cell divide every minute, the number of cells get doubled at the end of each minutes. If a 100 ml beaker is filled in one hour, it will take 59 minute to fill 50 ml beaker.

The number of chromosome reduces to half at the end of meiosis cell division. If plant has 2n= 8 chromosome the number of chromosomes present in daughter cells after meiosis II is 4 only.