Question

Describe ultra structure types and functions of chromosome notes

Answer 1

During the start of cell division, each chromosome appears in a condensed form. It consists of two chromatids( chromosomes which are not decondensed ) joined at some narrow, constricted portion of chromosome called centromere or kinetochore or primary constriction region. The region of chromosome on either side of the centromere is called arm.

The position of centromere is  fixed for a particular chromosome. Centromere is the place where spindle fibres are attached during cell division. Centromere is used to determine the shape of the chromosome and it provides attachment for spindle fibres.

There are four types of chromosomes which are dependent of the position of their centromere.

•    Telocentric : Centromere is present at the tale of the chromosomes or we can say, "occupying a terminal position"  so that they posses only one arm. They have rod - like shape.

•    Acrocentric : Centromere is neither located at the tale nor at the centre, centromere is located at little far away from the center. They are J shaped and rod like structure.

•    Submetacentric : Centromere is slightly away from the center. They are like L in shape.

•    Metacentric : Centromere is located at the center or just near to the center so that the length of both the opposite arms became equal. They are V shaped.