In the context of DNA structure, which of the following labels in a typical chromatin diagram indicates the nucleosome core particle?

• A. D. The free-floating histone proteins not associated with DNA
• B. B. The linker DNA connecting two adjacent beads
• C. C. The entire chromatin fiber including multiple nucleosomes
• D. A. The bead-like structure consisting of DNA wrapped around histone proteins

Answer: (D)

Verified step by step guidance

1. Understand the structure of chromatin: Chromatin is composed of DNA and proteins, primarily histones, organized to efficiently package DNA within the nucleus.
2. Identify the nucleosome core particle: It is the fundamental repeating unit of chromatin, consisting of DNA wrapped around a core of histone proteins, forming a bead-like structure.
3. Distinguish between the options: Recognize that free-floating histone proteins (option D) are not part of the nucleosome, linker DNA (option B) connects nucleosomes but is not the nucleosome itself, and the entire chromatin fiber (option C) is a higher-order structure made of multiple nucleosomes.
4. Match the description to the nucleosome core particle: The bead-like structure of DNA wrapped around histone proteins corresponds exactly to the nucleosome core particle, which is option A.
5. Conclude that the nucleosome core particle is represented by the bead-like structure consisting of DNA wrapped around histone proteins, as described in option A.