What are chromosomes primarily made of?

Chromosomes are primarily composed of DNA and proteins. DNA, or deoxyribonucleic acid, carries the genetic information that dictates the development, functioning, growth, and reproduction of all living organisms. The structure of DNA is organized into a double helix, which allows for the efficient packaging of its length into the compact form necessary for chromosomes.

Proteins, particularly histones, play an essential role in the packaging of DNA within chromosomes. Histones assist in winding the DNA around themselves, forming a structure known as chromatin. This organization is crucial for DNA to fit within the nucleus of a cell and for the regulation of gene expression. The combination of DNA and proteins allows chromosomes to maintain their stability and integrity, as well as to participate in cellular processes such as cell division and replication, ensuring accurate distribution of genetic material to daughter cells.

The other options mention components that do not make up chromosomes. Ribosomes and RNA are involved in protein synthesis, dietary fiber and protein relate to nutrition, and fatty acids and glycerol are components of lipids, which are not involved in chromosome structure. This underscores the specificity of DNA and proteins as the primary structural components of chromosomes.