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 cells and carry hereditary information.


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


Spindle fibre: A Thread like structure is formed at the metaphase stage, in which chromosome are attached with centromere is called spindle fibre.


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


Interphase: The change that occur in newly formed cells till they are ready for the further 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: The identical male and female parent chromosomes occur in pair 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 chromatid is called crossing over.


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



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