The structure that makes up chromosomes is composed of DNA wrapped around proteins called histones. This organization arises during cell division when DNA condenses to form visible chromosomes, ensuring proper segregation into daughter cells. DNA holds genetic information in the form of genes, which dictate various biological traits and functions. The distinct, tightly packed structure of chromosomes allows for efficient DNA replication and repairs mechanisms. Additionally, the expression of genes from these chromosomes is crucial for cellular functions and overall organism development. Thus, chromosomes play a vital role in heredity and genetic diversity.