What are chromosomes?

• A. Proteins
• B. RNA strands
• C. Threadlike structures made of DNA molecules that contain the genes
• D. Lipids

Answer: (C)

Chromosomes are threadlike structures in the cell nucleus that organize and carry genetic information. They are made of long DNA molecules wrapped around proteins called histones, forming chromatin. Each chromosome contains many genes, which are specific DNA sequences that provide instructions for making proteins or RNA molecules. During cell division, chromosomes condense and become visible as distinct structures. This differs from proteins, which are the workhorses of the cell; from RNA strands, which carry genetic messages but aren’t organized into chromosome structures; and from lipids, which form membranes and energy stores rather than genetic material.