gametogenesis

[zonia30]

can anybody please explain this process to me in plain easy to understand words its my exams in june and this is one part i cannot figure out at all!!!

[Doc44]

Generally speaking, gametogenesis is the production of gametes, sex cells, sperm and egg. In animals it takes place in gonads; testis and ovary. The process involves meiosis, reduction division and mitosis, regular cell division. The resulting gametes have only one half the number of chromosomes as the organism's somatic, body, cells. Humans have 46 chromosomes (diploid, 2N) and their gametes only have 23 chromosomes (haploid 1N).....so when a sperm combines with an egg (fertilization) the resulting zygote has 46. This maintains a constant number of chromosomes in a species from generation to generation.

Doc44

Biologically speaking, the only function of an organism is to survive long enough to reproduce......good luck.

[zonia30]

cheers doc! so basically the cell replicates first then begins to divide is that right??????

[Doc44]

cheers doc! so basically the cell replicates first then begins to divide is that right??????

That is what happens in mitosis. In gametogenesis there is division by meiosis before the division by mitosis.
In higher animals there are two forms of gametogenesis; spermatogenesis and oogenesis. Here is a pretty good diagram of spermatogenesis. See if this helps.

Spermatogenesis

http://www.umanitoba.ca/faculties/scien ... enesis.jpg

Doc44

If still not clear I will splain it.

[atypical10]

Gametogenesis is basically the production of gametes, gametes are sex cells either sperm (male) or egg (female). During meiosis, after two sucessive dvisions four haploid gametes are produced and chromoso-
-ome numbers are reduced by half.

[zonia30]

cheers that website helped xxx
so see if im right i only need the basics
a cell 46 chromosomes replicates (mitosis) itself
1st meiotic division occurs producing 2 cells containing 23 chromosomes
2nd meiotic division occurs producing another 2 daughter cells still containing 23 ????????????????????????????????????????
now i get confused
please help i usually ok at understanding things but this is winding me up i cant get it like i said i only need to know basics of both sperm and ooogenesis whatever lol
thanks alot i appreciate it

[MrMistery]

the cells with 23 chromosomes formed after meiosis I are each composed of 2 sister chromatids, while ones formed after meisis II have only one chromatid each

[zonia30]

thanks for that think its finally sunk in thanks for all the help xx

[jnkdna]

hey did u have ur exams today? june 5th dat is.