The genetic material that makes up chromosomes is DNA (deoxyribonucleic acid). In eukaryotic cells, chromosomes consist of long, linear DNA molecules tightly coiled and wrapped around proteins called histones. This DNA-protein complex is known as chromatin. The DNA itself carries genetic information through sequences of bases (adenine, thymine, cytosine, and guanine) organized into genes. The DNA is packaged into structural units called nucleosomes, formed by DNA wrapped around histone octamers, facilitating DNA compaction and regulation of gene activity. Chromosomes also contain other proteins that play roles in chromosome structure and function, including centromeric and telomeric proteins that help in chromosome stability and cell division. This dense and organized packing allows chromosomes to effectively store and transmit genetic information within cells.