Cell Division

[BioGirl]

I've always wondered, what happens to organelles when cells divide? Do parts of the organelles from the old cell go into the new cell, or does the new cell grow its own organelles? That's probably a stupid question, but I'm curious!!

[biostudent84]

The old ones remain...some in each new cell created. If there are not enough organelles for both cells, each will produce more so there is a sufficient amount to run the cell.

[BioGirl]

How stupid is that? They just appear? WHAT IS THAT?

[Poison]

I couldnt understand what you are saying? just appear????? they replicate themselves or synthesized before division. not just appear.

[thank.darwin]

How stupid is that? They just appear? WHAT IS THAT?

Some of the cells organelles can replicate - mitochondria and chloroplasts - biostudent84, can other organelles self replicate before a cell divides?

[mith]

I think they all replicate themselves. If you look at the phases of the cell, you should notice there is a growth stage where the cell grows and a second phase where everything is duplicated in preparation for the big separation.

[thank.darwin]

I don't think all of them replicate... does anyone?

[Poison]

Someone correct me if I'm wrong but as much as I know not all organelles replicate themselves. The ones which have its own genetic material can replicate. For example: mitochondria, chloroplasts, centrioles, ribosomes.
The other ones are sythesized before the division starts. For example; lysosomes.

[DevGrp]

Mitochondria and chloroplasts do have their own genomes but these don't code for all the genes required for their own proteins, some of these are still manufactured by the nuclei genome, so they can't completely self replicate.

There is a theory that during the evolution of eukaryotic cells that mitochondria are actually bacteria which became traped inside the cell and algae were the precusors of chloropplasts. This might explain why they have their own DNA. They have obviously heavily evolved since then.

[thank.darwin]

DevGrp, correct me if I'm wrong; Mitochondria do self replicate and they do it all the time - not just when the cell is splitting...?

[DevGrp]

As far as I know they divide all the time, all I was saying is that they require protein from nuclear encoded genes as well as their own genes

[Poison]

Thats right DevGrp, mitochondria can divide (if needed) without cell division.