What is a chromosome primarily made up of?

A chromosome is primarily composed of DNA. DNA, or deoxyribonucleic acid, is the molecule that carries the genetic information necessary for the growth, development, functioning, and reproduction of all living organisms. Within the structure of a chromosome, DNA is tightly coiled and packaged around proteins known as histones. This organization helps to condense the DNA to fit within the nucleus of the cell, while also playing a crucial role in regulating gene expression and DNA replication.

While proteins are indeed a part of the chromosome structure, serving as scaffolding that supports the DNA, it is the DNA itself that is the fundamental component that encodes genetic information. RNA, while involved in protein synthesis and other cellular functions, is not a primary component of chromosomes. Carbohydrates do not play a direct role in the composition of chromosomes, although they may be present in small amounts as components of nucleotides. Overall, the defining characteristic of a chromosome is the presence of DNA.