Cell Division

[computerages]

Hey everyone!

 

I am curetlly studying about the process of "Cell Division" in my biology class. But I am unable to understand it, could you guys please tell me what it is all about?

 

Thank you very much!

[Tommio]

This is kinda sketchy

 

There are two types of cell division mitosis and meiosis.

 

mitosis is the cloning of one cell. It gives the affect of doubling the number of cells you have. This is what you see in those pictures of bacteria multiplying that are everywhere.

 

The cell goes through -

 

Prophase - the DNA in the cell nucleus begins to duplicate thus becoming thicker.

 

Metaphase - The nuclear envelope breaksdown as the chromosomes move to the centre. There are now two centrioles, one at either pole. these are responsible for creating spindles that the chromosomes attach too, via the centromere.

 

Anaphase - The chromosomes pull apart and move to each pole.

 

Telophase - the chromosomes are now contained in a new nuclear envelope and there is one centriole per nucleus. Next is cytokenesis which means cell splitting. The cell membrane pinches in and eventually meets in the middle - and you now have two genetically identical cells.

 

Meiosis is what happens to form gametes - sex cells.

 

It is divided into meiosis I and II

 

IN 'I' -

 

Prophase - homologous chromosomes pair up and cetrioles move to opposite ends of the nucleus. The envelope begins to breakdown, the nucleolus 'disappears'. So far it is the same a mitosis but next is crossing over. This is where the pairs of chromosomes next to each other can 'swap' parts. This aids genetic diversity.

 

Metaphase - this is where the chromosomes line up next to each other.

 

Anaphase - Instead of the centromeres splitting the whole chromosome lined up in the cell moves along the spindles.

 

Telophase - is the same as mitosis.

 

Most animal cells do divide and then divide again but plant cells usually do this and the next stage in one cell.

 

Meiosis II is an exact copy of meitosis.

 

I hope this helped and was detailed enough.