Question

My biology class is talking about the cell and one description was the following: Chromatin: The combination of DNA and proteins that constitutes chromosomes; often used to refer to the diffuse, very extended form taken by the chromosomes when a eukaryotic cell is not dividing. I don't really understand the part about eukaryotic cell's not dividing. Can anyone explain this to me? Thanks!

Answer 1

First, we should define what chromatin is. Chromatin is the way in which DNA is presented in the cell nucleus. It is substance of eukaryotic chromosomes, which corresponds to the composition of DNA, RNA and proteins found in the nucleus of eukaryotic cells and that constitutes the genome of these cells. Its chemical constitution is simply DNA strands in varying degrees of condensation.

During the most life time of the cell (before cellular division), the chromatin is decondensed which means that it is composed by long and thin DNA chains that looks diffused under the microscope. In this way, the proteins involved in the DNA replication are able to access in a easier way into the DNA which at the same time allows that the cell proliferate.

The condensation of the chromatin occurs when the cell is nearly to divide. When the chromatin is condensed we can observe under the microscope that DNA is not only a long chain. In fact, it is conformed by linear fragments called chromosomes.