Thread: Cell Division

I cannot seem to find details on how the organelles in a cell divide during cell division. It seems everyone only cares about the process of the DNA replicating. Could someone fill me in?

Thanks.

Originally Posted by Cold Fusion

I cannot seem to find details on how the organelles in a cell divide during cell division. It seems everyone only cares about the process of the DNA replicating. Could someone fill me in?

Thanks.

Most organelles aren't self-replicating, which means they don't divide, at cell division or any other time. Broadly speaking, they're formed via complex interactions of primary and secondary products of the genome, ie proteins and metabolites. As I understand it (and I'm rusty on this) they're manufactured on demand by the nucleus, which would mean that whatever organelles are present at the time of cell division are portioned out between the two daughter cells, probably by chance of where they're located relative to the axis of division, and then as the new daughter cells grow, new organelles are constructed as needed.

Possible exceptions to this would be mitochondria and chloroplasts, about which I know very little I'm afraid.

Originally Posted by TheBiologista

Possible exceptions to this would be mitochondria and chloroplasts, about which I know very little I'm afraid.

I think it was these, with their own gentic templates, that cold fusion was thinking of.

The inheritance of mitochondrial and chloroplast genes differs from that of nuclear genes in showing vegetative segregation, uniparental inheritance, intracellular selection, and reduced recombination. Vegetative segregation and some cases of uniparental inheritance are due to stochastic replication and partitioning of organelle genomes. The rate and pattern of vegetative segregation depend partly on the numbers of genomes and of organelles per cell, but more importantly on the extent to which genomes are shared between organelles, their distribution in the cell, the variance in number of replications per molecule, and the variance in numerical and genotypic partitioning of organelles and genomes. Most of these parameters are unknown for most organisms, but a simple binomial probability model using the effective number of genomes is a useful substitute. Studies using new cytological, molecular, and genetic methods are shedding some light on the processes involved in segregation, and also on the mec hanisms of intracellular selection and uniparental inheritance in mammals. But significant issues remain unresolved, notably about the extent of paternal transmission and mitochondrial fusion in mammals.

Source: Birky, C.W. junior "The Inheritance of genes in mitochondria and chloroplasts: Laws, mechanisms, and models." Annual Review of Genetics, January 01, 2001

Go here for the full article.

What about the organelles that are only present in a single quantity such as the golgi apparatus? Is it simply split in two?

The golgi is disassembled like the nucleus and reassembled in each cell after mitosis.

By disassembled, do you mean destroyed entirely, or broken apart like a puzzle and reassembled in its new respectful position?

Kind of like a jig saw puzzle.

http://www.ncbi.nlm.nih.gov/bookshel...per&part=A1373

Edit: The link doesn't mention the golgi specifically, but as a phospholipid membrane structure I imagine the mechanism is probably similar to that of the nucleus and ER.

Thanks for the information; now, on with my research....