Structure of Chromosomes – Notes
The nucleus is surrounded by a nuclear envelope or nuclear membrane.
The nuclear envelope consists of the outer membrane and inner membrane.
At a number of places, the two membrane fuse and give rise to minute pores called nuclear pores.
Present inside the nuclear envelope is the nucleoplasm, the nuclear matrix that contains the nucleolus, a spherical structure that membrane.
The nucleoplasm also contains chromatin, a network of highly extended and elaborate nucleoprotein fibres.
When a cell begins to divide, the chromatin condenses and coils to form rod- like structures called chromosomes.
A chromosome consists of a primary constriction or centromere that has disc- shaped structures called kinetochores attached to its side.
Based on the position of the centromere, chromosomes can be classified as metacentric, sub- metacentric, acrocentric and telocentric.