The arrangement of aminoacids in a polypeptide is determined by

Options

A. DNA
B. r-RNA
C. S-RNA
D. t-RNA

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the factor that determines the arrangement of amino acids in a polypeptide chain.

2. **Role of mRNA**: The arrangement of amino acids in a polypeptide is primarily determined by the sequence of codons in messenger RNA (mRNA). Each codon corresponds to a specific amino acid.

3. **Codons and Amino Acids**: Codons are sequences of three nucleotides in mRNA that specify which amino acid will be added next during protein synthesis. For example, the codon AUG codes for Methionine, which is often the start codon.

4. **Transcription Process**: The mRNA is synthesized from DNA during the process of transcription. The sequence of bases in the DNA is transcribed into a complementary sequence in mRNA.

5. **Translation Process**: During translation, the ribosome reads the mRNA sequence and uses tRNA (transfer RNA) to bring the appropriate amino acids in the order specified by the mRNA codons.

6. **Conclusion**: Therefore, the arrangement of amino acids in a polypeptide is determined by the codons in mRNA, which are ultimately derived from the DNA sequence.

7. **Final Answer**: The correct answer is that the arrangement of amino acids in a polypeptide is determined by the DNA sequence, as it dictates the sequence of mRNA.

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