What is a centromere? How does the position of the centromere form the basis of the classification of chromosomes? Support your answer with a diagram showing the position of the centromere on different types of chromosomes.
Eukaryotic chromosomes: The chromosomes are uncoiled in a loose, indistinct network called the chromatin that contains DNA, RNA and protein in interphase. The types of proteins present and associated with DNA are histone and non-histone proteins. Chromosomes are thread-like structures. They become visible (under light microscope) during cell division. In higher organisms, the well-developed nucleus contains a definite number of chromosomes of definite size and shape. The shape of a chromosome is usually observable at metaphase and anaphase when the position of primary constriction {centromere) is clearly seen. Based on the position of the centromere, chromosomes are of 3 types: telocentric – with terminal centromere, the acrocentric – terminal centromere is capped by a telomere submetacentric – the centromere is subterminal in position metacentric – these have median centromere.
