Which of the following best describes a nucleosome?

• A. A segment of DNA wrapped around a core of histone proteins
• B. A double-membraned structure that contains the cell's genetic material
• C. A membrane-bound organelle responsible for protein synthesis
• D. A vesicle involved in the breakdown of cellular waste

Answer: (A)

Verified step by step guidance

1. Understand the term 'nucleosome': A nucleosome is a structural unit of chromatin in eukaryotic cells, consisting of DNA wrapped around histone proteins.
2. Recall the role of histone proteins: Histones are positively charged proteins that help package negatively charged DNA into a compact structure, enabling efficient storage within the nucleus.
3. Visualize the structure: A nucleosome consists of approximately 147 base pairs of DNA wrapped around a core of eight histone proteins (two each of H2A, H2B, H3, and H4). This structure resembles 'beads on a string' when viewed under a microscope.
4. Eliminate incorrect options: The other options describe unrelated cellular structures or functions, such as double-membraned organelles (e.g., nucleus), protein synthesis (e.g., ribosomes), and waste breakdown (e.g., lysosomes).
5. Conclude that the correct description of a nucleosome is 'A segment of DNA wrapped around a core of histone proteins,' as this matches the biological definition and structure of a nucleosome.