An octamer of four histones complex with DNA is claled

Options

A. Endosome
B. Nucleosome
C. Raf
D. Nucleotin

Answer

To solve the question "An octamer of four histones complex with DNA is called," we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Components**:
- The term "octamer" refers to a complex made up of eight units. In this context, it refers to a group of histone proteins.
- Histones are proteins that help package DNA into a compact, organized structure.

2. **Identify the Histone Composition**:
- The question mentions "four histones." However, it is important to note that histones come in pairs, and the histone octamer is actually composed of two copies each of four different histone proteins (H2A, H2B, H3, and H4). This totals to eight histone proteins.

3. **Relate to DNA**:
- The histone octamer interacts with DNA, allowing the DNA to be wrapped around it. This structure is crucial for the organization of DNA within the nucleus of eukaryotic cells.

4. **Define the Structure**:
- The structure formed by the DNA wrapped around the histone octamer is known as a nucleosome. Each nucleosome consists of approximately 147 base pairs of DNA wrapped around the histone core.

5. **Eliminate Incorrect Options**:
- Endosome: A cellular structure involved in the transport of materials within the cell.
- RAF: An acronym for rapidly accelerated fibrosarcoma, which is unrelated to DNA packaging.
- Nucleotide: The basic building block of nucleic acids, consisting of a sugar, a phosphate group, and a nitrogenous base.

6. **Conclusion**:
- Based on the definitions and the structure described, the correct answer to the question is "nucleosome."

### Final Answer:
The octamer of four histones complex with DNA is called a **nucleosome**.