Question

What is the characteristic feature of a metacentric chromosome?
A. Metacentric chromosome has centromere in the middle and its two arms (chromatids) are almost equal in length.
B. Metacentric chromosome has centromere in the side and its two arms (chromatids) are not equal in length
C. Metacentric chromosome has centromere in the end and its two arms (chromatids) are equal in length
D. None of the above

Answer 1

Chromosomes contain DNA, which is the genetic material of an organism. It consists of sources of information for carrying proteins. It is of different shapes based on morphological and shape classification. It is divided into four types based on the length of chromosome arms and position of the centromere. They are metacentric, sub-metacentric, acrocentric and telocentric. Centromere is helpful in dividing the chromosome into chromosome arms.

Complete answer:
Option A Metacentric chromosome has centromere in the middle and its two arms (chromatids) are almost equal in length: In metacentric chromosome, centromere is present and is located in the middle of the chromosome, dividing it into two equal arms. In the metaphase stage of cell division, they look V-shaped.
In the sub-metacentric chromosome, the centromere is located near to one of the ends, dividing the chromosome into two unequal arms. During cell division, they are observed as L-shaped.
In the acrocentric chromosome, the centromere is present at one extreme end, leading to formation of one extreme smaller arm and one larger arm.
In the telocentric chromosome, the centromere is located in the proximal area and there is only one arm.
Option A is not correct
Option B Metacentric chromosome has centromere in the side and its two arms (chromatids) are not equal in length: Arms are equal in the metacentric chromosome.
Hence, Option B is not correct
Option C Metacentric chromosome has a centromere in the end and its two arms (chromatids) are equal in length: Centromere is present at the central position.
So, Option C is not correct.
Option D None of the above: Option A is the right answer and hence this option is not possible.
Option D is not correct.

So, the correct answer is “Option A”.

Note:
Most of the chromosomes present in humans are submetacentric. Metacentric chromosomes are present in amphibians. A few chromosomes possess non-staining and secondary fragments called satellite regions. In different phases of the cell cycle, the size and shape of chromosomes change. In the interphase stage, they look like coiled, thin and thread-like structures.