Introduction to the NUCLEUS
The presence of the nucleus is the main difference between prokaryotes and eukaryotes.
It has two main functions: on one hand, the storage of genetic information, on the other, the control of that same information.
The cell possesses all the information, but the expression is regulated because it manifests itself only the information necessary for each kind of cell.
The nucleus is just another organelle, it forms with the endoplasmatic reticulum by incavation of the membrane.
In the formation of actual cells, the ancestors are original eucaryote cells, and before that original procaryote ones.
The DNA ( Desoxyde Nucleotic Acid ) has a role in the storage of genetic information.
The DNA is a helicoidal molecule made by two chains of nucleotides in two different (opposed) directions.
- What are the nucleotides ?
They are formed by:
> Desoxiribose, a pentose sugar.
> Storified phosphate group.
> Nitrogenous base.