Number of nucleosomes found in helical coil of 30nm chromatin fibre ius

Options

A. 6
B. 10
C. 12
D. 15

Answer

To solve the question regarding the number of nucleosomes found in a helical coil of 30nm chromatin fiber, we can follow these steps:

### Step 1: Understand the Structure of Chromatin
Chromatin is made up of DNA and histone proteins. The basic unit of chromatin is the nucleosome, which consists of a segment of DNA wrapped around a core of histone proteins.

### Step 2: Identify the Composition of a Nucleosome
A nucleosome consists of an octamer of histone proteins (H2A, H2B, H3, and H4), which means there are 8 histone proteins in total. The DNA wraps around this octamer to form the nucleosome structure.

### Step 3: Determine the Diameter of Chromatin Fiber
The 30nm chromatin fiber is a higher-order structure of nucleosomes. It is formed when nucleosomes coil and fold together.

### Step 4: Calculate the Number of Nucleosomes in 30nm Fiber
Typically, each nucleosome occupies about 200 base pairs of DNA. In a 30nm chromatin fiber, the average number of nucleosomes can be estimated based on the length of the DNA present.

### Step 5: Use the General Knowledge of Nucleosome Packing
In a 30nm chromatin fiber, it is generally accepted that there are approximately 6 nucleosomes per 30nm of chromatin fiber.

### Conclusion
Therefore, the number of nucleosomes found in a helical coil of 30nm chromatin fiber is **approximately 6**.

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