Chromosome , the microscopic threadlike part of the cell that carries hereditary information in the form of genes. In the nuclear chromosomes of eukaryotes, the uncondensed DNA exists in a semi-ordered structure , where it is wrapped around histones (structural proteins), forming a composite material called chromatin. What are Chromosomes? In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.