- Cell happen to be fundamental unit of life.
- New cells will arise from existing cells.
- A cell will divide to give rise to two cells and these two cells can form four cells and so on. This is termed as “Cell reproduction” or “Cell division“.
- Cell division usually occur by Mitosis or Meiosis .
Following are the few differences between Mitosis and Meiosis:
|Definition||Mitosis is type of cell division occurring in somatic cells to form to identical daughter cells.||Meiosis is type of cell division occurring in germ cells cells to form to four haploid cells with varied genetic information compared to parental cells.|
|Function||Forms all kinds of cells required for growth and repair. Do not form gametes or sex cells||Formation of gametes – Sperm and egg|
|Place of occurrence||Somatic cells||Germ or reproductive cells|
|No. of stages||one||Completes in two stages|
|Prophase||Simple and short||Longer with many sub stages|
|Crossing over||Absent||Present to form gametes with different genetic identity|
|Pairing of homologous chromosomes||No||Yes. Pairing observed from zygotene of prophase I till metaphase I.|
|Mother cell or parental cell||Can be haploid or diploid||Always diploid|
|Metaphase||centromere towards equatorial plate and ends of chromosomes point to poles||At metaphase I, Centromere in towards poles and Chromosome ends towards equatorial or metaphase plate.|
|Homologous chromosomes||Homologous chromosome are not separated.||Homologous chromosome gets separated at anaphase I.|
|Centromere division||Centromere division takes place at anaphase I.|
Sister chromatids gets separated.
|Centromere division and sister chromatid separation takes place only at anaphase II|
|Spindle fibers||Completely disappear at telophase I||Doesn’t disappear completely by telophase I|
|Telophase I||Two copies of each chromosome (homologous chromosomes) end up at poles.||Single copy (but replicated ) of each chromosome (haploid) end up at pole at the end of telophase I|
|Chromosome number||Remains same as parental cell||Reduced to half ( 2n to n)|
|Type of reproduction||Asexual||Sexual|
|Daughter Cell||The genetic make up of daughter cells are identical to parental cell. (diploid)||The genetic constitution of daughter cells usually differs from parental cell due to crossing over – each chromosome will a mix of both paternal and maternal genes. Independent assortment of homologous chromosomes at metaphase I also adds to genetic constitution variation observed in embryo, formed after fertilization.|
Daughter cells formed are haploid.
|Walther Flemming||Oscar Hertwig|
Image Credit: Biology openstax