A core of eight histone proteins wrapped by two turns of DNA is known as

Options

A. chromatin
B. nucleosome
C. chromosome
D. non-histone protein

Answer

To answer the question "A core of eight histone proteins wrapped by two turns of DNA is known as," we will follow these steps:

### Step-by-Step Solution:

1. **Understanding Histones**:
- Histones are proteins that help package DNA into structural units called nucleosomes. They are positively charged, which allows them to bind tightly to the negatively charged DNA.

**Hint**: Remember that histones are crucial for DNA packaging in the nucleus.

2. **Identifying the Structure**:
- The question specifies a "core of eight histone proteins." This refers to an octamer, which is a structure made up of eight histone proteins.

**Hint**: Think about how many histones make up the core of a nucleosome.

3. **DNA Wrapping**:
- The DNA wraps around this octamer of histones approximately 1.65 times, which is often described as two turns of DNA.

**Hint**: Visualize how DNA coils around the histone proteins to form a compact structure.

4. **Defining the Nucleosome**:
- The combination of the octamer of histones and the wrapped DNA is specifically known as a nucleosome. This is the fundamental unit of chromatin structure.

**Hint**: Recall that nucleosomes are the building blocks of chromatin.

5. **Eliminating Incorrect Options**:
- **Chromatin**: This is a complex of DNA and proteins, but it is not the specific structure described in the question.
- **Chromosome**: This is a higher-order structure made up of chromatin and is not the answer.
- **Non-histone proteins**: These proteins play roles in gene regulation but are not involved in the core structure described.

**Hint**: Focus on the specific structure being asked about, rather than broader terms.

### Final Answer:
The correct answer is **Nucleosome**.