Gametes are formed from cells in the reproductive organs by a type of cell division called meiosis.
The cells that are formed by meiosis have half the number of chromosomes as a body cell (they are haploid).
The main features of meiosis are: –
• The cell divides twice, forming four gametes
• The gametes are genetically different from each other.
Meiosis creates variation by independent assortment of chromosomes and crossing over.
The points where chromatids break are called chiasmata. This is important in exchange of genetic material leading to genetic variation. Secondly errors in the process lead to mutations, introducing new combinations to the genetic make up of species. Cell division by meiosis results in the formation of gametes. Gametes are made in the sexual reproductive organs Cell division by meiosis results in an increase in number of genetically unique cells
There are two divisions that result in haploid cells Meiosis creates variation by independent assortment of chromosomes (during fertilisation) and crossing over (prophase 1)
The points where chromatids break are called chiasmata. This is important in exchange of genetic material leading to genetic variation. Secondly, errors in the process lead to mutations, introducing new combinations to the genetic makeup of species.
GAMETOGENESIS
Gametes are responsible for sexual reproduction
SPERM
Many, mini and motile:
the male gamete- spermatozoa ( sperm cells)
EGG
Few, fat and fixed:
The female gamete- Ova ( egg cells)