Chromosomes are found in the nucleus of each cell. It is a thread-like structure that is not visible in the cell’s nucleus. But at the time of cell division, it becomes more tightly packed, and then only it is visible under a microscope. Each chromosome joined at the centromere or the primary constriction and hence consists of two chromatids. These centromeres are the point of attachment of spindle fibers and play a vital role in cell division. On the basis of the position of the centromere, chromosomes are classified into the following types:
(1) Acrocentric chromosome: In this type of chromosome, the centromere is present at the sub-terminal. In the Anaphase stage chromosomes are J-shaped.
(2) Sub-metacentric chromosome: In this type of chromosome, the centromere is sub-median and the anaphasic chromosome appears L-shaped.
(3) Metacentric chromosomes: In this type of chromosome, the centromere is present in the middle and divides the chromosome into two equal parts. The chromosome appears V-shaped.
(4) Telocentric chromosome: In this type of chromosome, the centromere is present at the terminal. The anaphasic stage appears l-shaped.
Depending upon the number of centromeres, a chromosome is of different types.
(i) Monocentric: with a single centromere
(ii) Dicentric: with two centromeres
(iii) Polycentric: with many centromeres
(iv) Acentric chromosome: there is no centromere
Answered by Pragya Singh | 1 year ago
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