Types of Chromosomes

The classification of chromosomes is based on the centromere position, which falls into four types;

1-     Metacentric

2-     Sub-metacentric

3-     Acrocentric

4-     Telocentric.

The centromere of metacentric is precisely at the center, while the four chromatid arms have the same length.

In sub-metacentric, the centromere is located near the center. Two of its chromatide arms are longer than the other two.

The centromere of acrocentric is situated near the edge. The two chromatid arms are very long compared to the other two that are very short. There is a small filamentous structure with a round tip, known as satellite, near the tip of the short arms. The satellite is connected to the short arm by a short filament named nucleolar organizer region.

The centromere of telocentric is at the edge of the chromosome. It is only on one side that the two arms are situated.