Chromosomes are thread like structures, which can be easily observed and counting during metaphase stages of mitosis. Each chromosome has a point of attachment to the mitotic spindle, called the centromere. The position of centromere determines the shape of the chromosome.
The chromosomes are classified into four types according to their shape.
- Metacentric: The metacentric chromosomes are V-shaped and in these chromosomes the centromere divides into two equal arms. The amphibians have metacentric chromosomes.
- Submetacentric: If the centromere divides the chromosome into two unequal arms the chromosome is called submetacentric chromosome. The submetacentric chromosomes are L or J shaped.
- Acrocentric: In acrocentric chromosome the centromere is locted in such a way that a very short arm of chromosome is visible. The locusts Acrididae) have the acrocentric chromosomes.
- Telocentric: In telocentric chromosome the centromere is loctedat one end