What is a chromosome?

• A. A long DNA molecule packaged with proteins that carries genes.
• B. A small RNA molecule that carries amino acids.
• C. A lipid structure in the cell membrane.
• D. A protein that catalyzes chemical reactions.

Answer: (A)

A chromosome is a long DNA molecule packaged with proteins that carries genes, forming a compact structure that holds genetic information and ensures it can be accurately inherited during cell division. DNA contains the instructions for making proteins and other molecules; when wrapped around histone proteins, it forms chromatin, which condenses into visible chromosomes as a cell prepares to divide. This organization helps regulate which genes are active and makes it possible for the cell to evenly distribute genetic material to daughter cells.

Other descriptions point to different biomolecules: RNA molecules that carry amino acids are involved in building proteins, lipids are key components of cell membranes, and proteins that speed up chemical reactions are enzymes.