What would happen to the number of chromosomes in celss if we did not have processes like mitosis or meiosis?

Question

and why would this be bad?

Answer 1

First of all, you need to consider whether, in the abscence of either meiosis or mitosis, DNA replication would still occur. Moreover, you need to distinguish between mitosis and meiosis, as the outcome will be quite different.

In the case of mitosis:
- if DNA replication still takes place, then the number of chromosomes will grow exponentially with time and the cell will become polyploid. This is bad because it will lead to gene amplification and deregulation of the gene products (so, the cell would end up by producing too much of that particular enzyme, for example)
- if DNA replication does not occur, then the cell will be a non-dividing cell and cell proliferation will stop. This is not particuarly bad, and in fact most cells in the body are non-dividing if not stimulated. However, if the non-dividing cells should be dividing (as, for example, in the skin, gut mucosa, etc), then the tissue could undergo damage and lesions in the abscence of the needed proliferation.

In the case of meisosi:
- in the abscence of DNA replication (and cell division), sex cells will not form and the organism might become sterile.
- if DNA still takes place, but not the cell division, then the oocyte or sper will end up by being diploid. Now, after fecondation, the DNA of the two sex cells will fuse. In case of a diploid oocyte or sperm, fusing with a normal sperm?oocyte (resepcively), the resulting egg will be carrying 3 copies of each chromosome, which is very bad for the embryo - I don't think the egg will survive more than one or two cycles of division.

Answer 2

Mitosis divides up the copied DNA into two identical nuclei. This is important because the two daughter cells formed from cell division can be just like the parent cell was.

Meiosis divides up the copied DNA into four nuclei that have half the original number of chromosomes. This is important because the four daughter cells are the gametes (reproductive cells) that can join with other gametes and make new individuals that have the same number of chromosomes as the original parents.

Answer 3

we will eventually die because there will be no means to replace the cells that are dying.

Answer 4

we would die. without replicating cells all our cells would die off and we would be dead.

cells wouldnt be able to make new cells so they would all die off.

thats how its bad. :)