Cell Cycle and Cell Division Test - 8

The transition period between M-phase of Meiosis I and M-phase II during which no replication of DNA occurs is called as interkinesis. The cell undergoes preparation for the next round of division.

Crossing over results in the exchange of genetic material between two homologous chromosomes during meiosis I of cell division.

Rudolph Virchow was the first scientist who stated that new cells are formed from division of pre-existing cells. It is a part of cell theory postulated by Virchow in 1855.

Homologous chromosome are two similar chromosome of each type present in diploid cells. During meiosis homologous chromosomes separate from each other. In homologous pair, one chromosome is from mother while the other is from father.

Astral body are formed of protein microtubules. Astral bodies are produced by centriole during cell division and attach with centromere of the chromosome.

Human nerve cells do not divide after birth. These cells remain in Go phase throughout their life. In Go phase cells do not actually divide but undergo preparations for further division.

In Diploid cells, each homologous chromosome consists of one paternal and one maternal chromosomethat fuse together during fertilization of gametes. These chromosomes are called homologous chromosomes.

Polyploidy is the condition in which more than one set of chromosomes is present in one cell. It is the property of increasing the number of chromosome sets of the cell and results due to failire of segregration of non-sister chromatids after crossing over.

Egg yolk contains lampbrush chromosome where two homologous chromosomes with several chiasmata with several loops in chromatic region is found. They are also called giant chromosomes.

Number of chromosome changes during anaphase of meiosis I and amount of DNA content increaseS during S-phase of cell cycle. This is reflected in disturnace of nucleocytoplasmic ratio.