Chromosomes are divided into four parts based on the position of centromere.
(i) Metacentric Chromosome: Chromosome which lies in the center of centromere is called metacentric chromosome. During the anaphase phase of cell division, the metacentric chromosomes look like the English letter V. Amphibians have metacentric chromosomes. All chromosomes of Solanum nigrum are metacentric. Human chromosomes 1, 3, 6, 7, 8, 11, 16, 19, 20 and X are metacentric types.
(ii) Sub-metacentric chromosomes: Chromosome which is slightly away from the center of centromere is called sub metacentric chromosome. During the anaphase phase of cell division, the sub-metacentric chromosomes look like the English letter L. Human chromosomes 2, 4, 5, 9, 10, 12, 17 and 18 are of sub metacentric type.
(iii) Acrocentric Chromosome: Chromosome which is near the edge of centromere is called acrocentric chromosome. In the anaphase phase of cell division, acrocentric chromosomes look like the English letter O. All acrocentric chromosomes are sat-chromosomes. Human chromosomes 13, 14, 15, 21, 22 and Y are acrocentric types.
(iv) Telocentric Chromosome: Chromosome which is located at the extreme end of centromere is called telocentric chromosome. During the anaphase phase of cell division, the telocentric chromosomes look like the English letter I. Telocentric chromosomes are rare in organisms. Humans do not have telocentric chromosomes. Telocentric chromosomes are found in gymnosperms (Welwitschia) and onion (Allium).
[The dark purple variant of Typhonium trilobatum has 11 metacentric, 4 sub-metacentric and 2 acrocentric chromosomes]