Cell cycle



Cell cycle

It is the sequence of events in which cell duplicates its genetic material, synthesize the other constituents of cell and ultimately divide into two daughter cell.

Cell Division

The process in which cell increase in their number is called cell division. It is needed for growth, development and repair of body.
There are mainly two kind of cell division :
1. Mitosis
2. Meiosis

Mitosis

Mitosis cell division occur in somatic cell which take part in growth, repair and development. In unicellular organism asexual reproduction takes place by this type of cell division.
Significance of Mitosis
1. After Mitosis cell division one cell divided into two daughter cell in which number of chromosome is equal to the parent cell.
2. Uncontrolled Mitosis may cause tumor or cancerous growth.

Meiosis

1. Meiosis cell division occur in reproductive cell. This type of division takes place during the formation of haploid gamete, i.e. ova & sperm.
2. It is also known as reduction division during which each daughter cell have haploid number of chromosome.
3. Four daughter cells are produced from one meiotic cell division.

Terms related to cytology

Karyokinesis: Division of nucleus during cell division is called Karyokinesis.
Cytokinesis: Division of cytoplasm is called cytokinesis.
Diploid: Two complete set of chromosome is called diploid, found in somatic cell.
Haploid: Single set of chromosome in cell is called haploid, found in gametes.
Crossing over: Exchange of genetic material between two non sister chromatids takes place during meiosis cell division is called crossing over.
Homologous chromosome: A pair of chromosome having same size and shape bearing corresponding gene.
Allele: Alternative form of characters governed by gene.
Phenotype: The character of organism which can be seen directly.
Genotype : Genetic constitution of organism is called genotype.
Tonoplast: The membrane surrounding the vacuole.
Unit membrane : The basic trilamilar structure of cell membrane.