Which of the following structures are present in core particle of nucleosome?

Options

A. Octamer of histone proteins
B. 200 bp of DNA
C. Non-histone proteins
D. Linker DNA

Answer

To answer the question regarding the structures present in the core particle of a nucleosome, we can break down the components of a nucleosome and analyze each option provided.

### Step-by-Step Solution:

1. **Understanding the Nucleosome Structure**:
- A nucleosome is the fundamental unit of chromatin, consisting of DNA wrapped around a core of histone proteins.

2. **Identifying the Core Particle**:
- The core particle of a nucleosome consists of an octamer of histone proteins. This octamer is made up of two copies each of four different histone proteins: H2A, H2B, H3, and H4.

3. **Evaluating the Options**:
- **Option 1: Octamer of the histone proteins**: This is correct. The core of the nucleosome is indeed an octamer of histone proteins.
- **Option 2: 200 base pair of DNA**: This is incorrect. The core particle of a nucleosome typically has about 147 base pairs of DNA wrapped around it, not 200.
- **Option 3: Non-histone protein**: This is incorrect. Non-histone proteins are not part of the core particle of the nucleosome; they are involved in other functions in the chromatin structure.
- **Option 4: Linker DNA**: This is also incorrect. Linker DNA refers to the DNA that connects adjacent nucleosomes, not part of the core particle itself.

4. **Conclusion**:
- The only structure present in the core particle of a nucleosome is the **octamer of histone proteins**.

### Final Answer:
The structure present in the core particle of the nucleosome is the **octamer of histone proteins**.