Which of the following statements correctly describes eukaryotic histones in a nucleosome structure?

Options

A. A core histone heptamer plus a linker histone.
B. A core histone octamer plus a linker his tone.
C. A core histone plus a linker histone octamer.
D. A core histone octamer plus three linker histones.

Explanation

To solve the question regarding the correct description of eukaryotic histones in a nucleosome structure, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Nucleosomes**:
- Nucleosomes are the fundamental units of DNA packaging in eukaryotic cells. They consist of DNA wrapped around histone proteins.

2. **Identify the Components of Nucleosomes**:
- Each nucleosome contains a core of histone proteins and a segment of DNA. The core histones are typically composed of an octamer structure.

3. **Define the Core Histone Octamer**:
- The core histone octamer consists of eight histone proteins: two copies each of H2A, H2B, H3, and H4. This means there are a total of four different types of core histones, with two of each type.

4. **Linker Histones**:
- In addition to the core histones, there is a linker histone (commonly H1 or H5) that helps in the further compaction of the DNA.

5. **Analyze the Options Given**:
- Option 1: Core histone heptamer plus a linker histone (Incorrect, as it should be an octamer)
- Option 2: Core histone octamer plus a linker histone (Correct, as it accurately describes the nucleosome structure)
- Option 3: Core histone plus a linker histone octamer (Incorrect, as the octamer refers to the core histones)
- Option 4: Core histone octamer plus three linker histones (Incorrect, as typically only one linker histone is present)

6. **Select the Correct Answer**:
- Based on the analysis, the correct answer is **Option 2: Core histone octamer plus a linker histone**.