Question

The chromosomes in which centromere is situated close to one end are
A) Telocentric
B) Sub-metacentric
C) Metacentric
D) Acrocentric

Answer 1

Chromosome consists of a DNA molecule with the genetic material of an organism. The morphological classification that is based on the shape of chromosomes of an organism is an important karyotypic feature. Chromosomes contain information sources for carrying protein and have different kinds of shapes.

Complete answer:
In the different phases of the cell cycle, that is the repeated cycle of cell growth and division the size and shape of chromosomes changes like in interphase, they appear thin, coiled, and thread-like structures.

Moreover, in meiotic and mitotic cell division they appear thicker and shorter in length. Every chromosome consists of a primary constriction known as centromere that possesses a disc-shaped structure on its side called kinetochores. The centromere helps to divide the chromosome into two portions called chromosomes arms.

Based on the position of centromere and length of chromosomes arms, the chromosomes are group into four different types:
i) Telocentric: In this chromosome, the centromere is situated at the proximal end that resulted in only one arm. The chromosomal tips are termed as telomeres.
ii) Sub-metacentric: This type of chromosome possesses a centromere nearer to one end of the chromosome that leads to occurrence of one shorter arm and one long arm. They are observed in 'L'shape structure during cell division.
iii) Metacentric: In this chromosome, the centromere is present and situated in the middle of the chromosome and divides it into equal arms. These chromosomes are observed as V shapes in the metaphase stage of cell division.
iv) Acrocentric: In this type of chromosome, the centromere is present close to its end which leads to one extremely short arm and one very long arm. Sat-chromosomes constitute all acrocentric chromosomes.

Thus the correct answer is option ‘A’ i.e, Acrocentric.

Note:

Few chromosomes have properties of possessing non-staining secondary constrictions at a fixed place that shows a small fragment called the satellite.
Amphibians generally possess metacentric chromosomes.
Most of the human chromosomes that occur are sub metacentric.