It is a very complex and long phase. It is further divided into five successive substages.

1. Leptotene or Leptonema
2. Zygotene or Zygonema
3. Pachytene or Pachynema
4. Diplotene or Diplonema
5. Diakinesis

1. Leptotene[ GK: Leptos=thin, tene= Thread ]

• size of nucleus increases
• chromatin thread become shortened and converted into chromosomes which are thread like and single stranded.
• chromosomes passes beaded structure called chromomeres.

2. Zygotene[ GK: Zygo= yolk, tene= thread]

• pairing of homologous...

Crossing over is a process of exchange of genetic materials between the non-sister chromatids of homologus chromosomes. It takes place in pachytene of prophase-I of meiosis.

It has following significances:

1. It produces new combination of genes and trait.
2. it increases variability of organisms.
3. Due to crossing over, different varieties of plants and animals are produced.
4. Crossing over helps in the identity of organism.
5. It is a source of raw material for evolution of life.
6. It increase immunity of...

Furrowing is a type of division of cytoplasm occurs in the bacteria, fungi and animal cells. In this process, a peripheral cleavage furrow appear gradually between the two daughter nuclei.

The furrow deepens and when the edges of the furrow meet in the center of the cell, the protoplasm divides into two daughter cells.

Mitosis is a type of cell division where a mature mother cell divides to form two daughter cells which are identical to each other as well as with mother cell.

The importance of mitosis are as follows:

1. It keeps the chromosome number constant and genetic stability in daughter cells, so the linear heredity of an organism is maintained.
2. It helps in growth and development of zygote into adult in multicellular organisms.
3. It provides new cells for repair and regeneration of lost part and healing of...