Histones are classified as what type of biological molecule?

Histones are classified as proteins, which play a crucial role in the organization and packaging of DNA within the cell nucleus. These proteins have a high content of positively charged amino acids, such as lysine and arginine, allowing them to interact effectively with the negatively charged DNA. This interaction is essential for the formation of nucleosomes, the fundamental units of chromatin. Each nucleosome consists of a segment of DNA wrapped around a core made of histone proteins, facilitating the tight compaction of DNA that is necessary for proper gene regulation and cell division.

In contrast, carbohydrates primarily serve as energy sources or structural components, lipids are involved in cell membrane structure and energy storage, and nucleic acids, such as DNA and RNA, consist of nucleotide chains that store and transfer genetic information. Therefore, the unique characteristics and functions of histones align them with proteins rather than any other type of biological molecule.