A naturally occurring coding strand composed of alternating C and U residues would result in the formation of

Options

A. A polypeptide containing alternating leu and ser residues
B. A polypeptide containing either leu or ser residues
C. A polypeptide containing only leu residues
D. A polypeptide containing only ser residues

Answer

To solve the question regarding the naturally occurring coding strand composed of alternating C and U residues, we will follow these steps:

### Step 1: Understand the Coding Strand
The coding strand is composed of alternating cytosine (C) and uracil (U) residues. This means the sequence can be represented as:
C-U-C-U-C-U...

### Step 2: Determine the Codon Structure
In molecular biology, codons are sequences of three nucleotides that correspond to specific amino acids. Since our coding strand alternates between C and U, we will group the nucleotides into codons of three:
- The first codon: C-U-C
- The second codon: U-C-U
- The third codon: C-U-C
- The fourth codon: U-C-U
- And so on...

### Step 3: Translate Codons to Amino Acids
Now, we need to determine which amino acids these codons correspond to:
- The codon C-U-C codes for Leucine (Leu).
- The codon U-C-U codes for Serine (Ser).

### Step 4: Identify the Pattern
From the alternating sequence of codons, we can see that:
- The polypeptide will alternate between Leucine and Serine.
- Therefore, the resulting polypeptide will contain repeating units of Leucine and Serine.

### Step 5: Conclusion
Based on the analysis, the final answer to the question is:
**A polypeptide containing alternating leucine and serine residues.**