Nucleus is a double membrane bound structure present inside the cell.
The membrane of the nucleus is called a nuclear membrane.
The nuclear membrane shows the presence of the small pores called nuclear pore.
Nuclear pore allows the transport of the substances in and out of the nucleus.
The major component present inside the nucleus is genetic material of the organism, that is DNA.
During cell division, DNA along with some protein forms a rod-like structure called chromosome.
When the cell does not undergo cell division, DNA along with some proteins forms an entangled mass of thread-like structure known as chromatin.
Chromosome is an organised form of chromatin which is formed only during cell division.
DNA is a chemical substance that has all the information of the composition and characteristic of an organism.
DNA is made up of many functional units known as genes. Each gene carries a message of each characteristic of an organism.
In some organisms like bacteria, the nucleus is not well developed and it lacks nuclear membrane. Such organisms are called prokaryotes where “pro” stands for primitive and “karyon” stands for nucleus.
Whereas the organisms that have well developed nuclei and show the presence of the nuclear membrane are called eukaryotes.