Select the option that correctly represents: coding sequence of DNA and Non- coding sequence of DNA, respectively.

Options

A. exon, intron
B. intron, exon
C. cistron, exon
D. exon, cistron

Answer

To solve the question regarding the coding and non-coding sequences of DNA, we need to understand the definitions and roles of exons and introns in the context of DNA and RNA.

### Step-by-Step Solution:

1. **Identify Coding and Non-Coding Sequences**:
- The coding sequence of DNA refers to the parts of the DNA that are transcribed into mRNA and then translated into proteins. These sequences are known as **exons**.
- The non-coding sequences are parts of the DNA that are transcribed into RNA but are not translated into proteins. These sequences are known as **introns**.

2. **Review the Options**:
- Option 1: Exon and Intron
- Option 2: Intron and Exon
- Option 3: Cistron and Exon
- Option 4: Exon and Cistron

3. **Analyze Each Option**:
- **Option 1**: Exon (coding) and Intron (non-coding) - This is correct.
- **Option 2**: Intron (non-coding) and Exon (coding) - This is incorrect.
- **Option 3**: Cistron (can refer to coding sequences but is more general) and Exon - This is incorrect as it does not directly represent the relationship between coding and non-coding sequences.
- **Option 4**: Exon (coding) and Cistron - This is incorrect for the same reason as option 3.

4. **Conclusion**:
- The correct representation of coding and non-coding sequences of DNA is given by **Option 1: Exon and Intron**.

### Final Answer:
**Option 1: Exon and Intron**