Cell Division and Its Types

Cell Division

Cell Division

Cell division is the process by which a Parent Cell divides into two or more Daughter Cell. Cell division usually occurs as part of a larger cell cycle. In eukaryotes, there are two distinct type of cell division: a vegetative division, whereby each daughter cell is genetically identical to the parent cell , and a reductive cell division, whereby the number of chromosomes in the daughter cells is reduced by half, to produce haploid gametes . Both of these cell division cycles are required in sexually reproducing organisms at some point in their life cycle, and both are believed to be present in the last eukaryotic common ancestor Prokaryotes also undergo a vegetative cell division known as binary fission, where their genetic material is segregated equally into two daughter cells. All cell divisions, regardless of organism, are preceded by a single round of DNA replication.

Types of Cell Division

Generally there are two types of cell division

1. Mitosis cell division :- It is the process by which new cells are generated. Mitosis is the process by which a cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei. It is a form of karyokinesis, or nuclear division. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles, and cell membrane into two cells containing roughly equal shares of these cellular components. Mitosis and cytokinesis together define the mitotic (M) phase of the cell cycle: the division of the mother cell into two daughter cells, genetically identical to each other and to their parent cell. This accounts for approximately 10% of the cell cycle.
2. Meiosis cell division :- It is the process by which gametes are generated for reproduction. Meiosis  is a special type of cell division necessary for sexual reproduction in eukaryotes. The cells produced by meiosis are gametes or spores. In many organisms, including all animals and land plants (but not some other groups such as fungi), gametes are called sperm and egg cells.Meiosis begins with one diploid cell containing two copies of each chromosome:one from the organism's mother and one from its father.

Basic terms to be more cleared on concept of Cell division are as follows :-
 Gene :- basic unit of heredity; codes for a specific trait   

Somatic cell :- all body cells except reproductive cells 

Locus :- the specific location of a gene on a chromosome (locus - plural loci)
Genome :- the total hereditary endowment of DNA of a cell or organism
Chromosome :-elongate cellular structure composed of DNA and protein - they are the vehicles which carry DNA in cells
Gamete :- reproductive cells (i.e. sperm & eggs)
Haploid (n) :- cellular condition where each chromosome type is represented by only one chromosome 
Diploid (2n) :-cellular condition where each chromosome type is represented by two homologous chromosomes
Chromatid :-one of two duplicated chromosomes connected at the centromere
Homologous chromosome :- chromosome of the same size and shape which carry the same type of genes
Centromere :-region of chromosome where microtubules attach during mitosis and meiosis