Question

Cistron is a segment of DNA coding for a :

• A. \( \text{Polypeptide only} \)
• B. \( \text{mRNA only} \)
• C. \( \text{Polypeptide, tRNA and rRNA} \)
• D. \( \text{mRNA, tRNA and rRNA} \)

Hint:

Remember that the central dogma of molecular biology describes the flow of genetic information as DNA $\rightarrow$ RNA $\rightarrow$ Protein. A cistron is the functional unit of heredity that carries the information for one polypeptide.

Answer 1

The Correct Option is A

A cistron is a segment of DNA that codes for a single polypeptide chain. In the process of gene expression, DNA is transcribed into messenger RNA (mRNA). This mRNA then serves as a template for the synthesis of a polypeptide chain during translation. Transfer RNA (tRNA) and ribosomal RNA (rRNA) are also transcribed from DNA, but they are coded by different DNA segments, not the same cistron that codes for a polypeptide. Therefore, a cistron primarily codes for a polypeptide.