Which term defines a condensed structure of DNA and proteins?

• A. Chromatid
• B. Chromosome
• C. Chromatin
• D. Centromere

Answer: (B)

The correct term that defines a condensed structure of DNA and proteins is "chromosome." During cell division, DNA is tightly packed around proteins called histones, forming a structure known as chromatin when not condensed. However, when a cell prepares to divide, chromatin further condenses to form distinct chromosomes, which makes the DNA more manageable and ensures accurate segregation during mitosis and meiosis.

In contrast, although "chromatid" refers to one half of a duplicated chromosome, it does not independently represent the entire condensed structure. "Chromatin" refers to the less condensed form of DNA and proteins present during interphase, which is not specifically defined as condensed. The term "centromere" refers to the region of a chromosome where sister chromatids are joined and does not encompass the entire structure comprising DNA and proteins. Thus, a chromosome is the most precise term for a condensed DNA-protein structure.