Definitions (Cell Division)

CELL DIVISION

Cell: Cell is defined as the structural and the functional unit of life.

Cell division: The process in which two or more daughter cells of same kind are formed from pre-existing cells is called cell division.

Chromosome: The thread like structure in the nucleus of a cell which carries hereditary information.

Genes: A tiny unit of heredity located in chromosome is called genes.

Spindle fibre: Thread-like structures formed during cell division (starting in prophase) to which the chromosomes are attached by their centromeres are called spindle fibres.

Centromere: The two chromatids of chromosome are joined to each other by a bead-like structure which is called centromere.

Interphase: The stage between two cell divisions in which the cell grows and prepares for the next division.

Karyokinesis: The process of division of nucleus during cell division.

Cytokinesis: The process of division of cytoplasm during cell division.

Sex chromosome: Those chromosomes which occur singly or in a pair and carry genes in determining the sex of the individual in unisexual organisms.

Autosomes: Those chromosomes which regulates the growth and development of the body of organism.

Chromatin fiber: The chromosome materials in the form of long and very loosely coiled thread are called chromatin fiber.

Mitosis Cell Division: The type of cell division in which a single diploid mother cell divides to form two diploid daughter cells is called mitosis cell division.

Haploid cell: The cell which contains single chromosome for each character is called haploid cell.

Diploid cell: The cell which contains two chromosomes for each character is called diploid cell.

Meiosis cell division: A type of cell division in which a diploid mother cell divides into four haploid daughter cells is called meiosis cell division.

Amitosis or Direct cell division: The type of cell division in which a cell divides into two daughter cells without the formation of spindle fibre and condensation of chromatin fibre is called amitosis or direct cell division.

Homologous chromosomes: A pair of similar chromosomes, one received from each parent, is called homologous chromosomes.

Synapsis: The phenomenon of pairing of homologous chromosome is called synapsis.

Crossing over: The process of exchanging genetic material between two non-sister chromatids is called crossing over.

Chiasmata: The point on which crossing over takes place is called chiasmata.