Chromatin Condenses to form chromosome when cell has to undergo division. Since Chromatin is basically DNA wrapped around positivel charged histone proteins. Chromatin further condensed to form chromosomes. Refer to the picture

Acentromereis a region on a chromosome that joins identical sister chromatids. This chromosome segment plays a major role in chromosome movement during ANAPHASE. it is actually the heterochromatin( HIGHLY CONDENSED CHROMATIN)