In human genome, random variations occur as often as one in every 200 nucleotides, in this DNA

Options

A. Unexpressed DNA
B. Expressed DNA
C. Structural DNA
D. None of these

Answer

To solve the question regarding the type of DNA where random variations occur as often as one in every 200 nucleotides in the human genome, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**:
- The question states that random variations occur in the human genome at a frequency of one in every 200 nucleotides. We need to determine what type of DNA this variation is associated with: unexpressed DNA, expressed DNA, structural DNA, or none of these.

2. **Types of DNA**:
- **Expressed DNA**: This refers to DNA that is transcribed into RNA and then translated into proteins. Variations in expressed DNA can lead to mutations that affect protein function.
- **Unexpressed DNA**: This refers to regions of DNA that do not code for proteins or are not involved in the expression of traits. Variations in these regions typically do not have immediate functional consequences.
- **Structural DNA**: This type of DNA is involved in forming the physical structure of chromosomes and may have specific functions. Variations here could disrupt structural integrity.

3. **Analyzing Random Variations**:
- Random variations occurring every 200 nucleotides suggest a non-critical role in the genome. If these variations were in expressed DNA, they could lead to mutations that would affect the organism's traits, which would not be sustainable across generations.
- Variations in structural DNA could lead to significant changes in the organism's structure and function, which is also not likely to occur randomly without consequences.

4. **Conclusion**:
- Given that expressed DNA and structural DNA would be adversely affected by random variations, the most logical conclusion is that these variations occur in **unexpressed DNA**. This type of DNA does not have a direct impact on the organism's phenotype and can tolerate variations without detrimental effects.

### Final Answer:
The correct answer is **unexpressed DNA**.

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