Codons UCA, UCG, UCU, UCC, AGC, and AGU code for the amino acid serine.
What do these codons indicate?

Options

A. that the genetic code is universal
B. that the genetic code is degenerate
C. that UCA is the initiator codon
D. that all amino acids are coded by six codons

Answer

To answer the question about the codons UCA, UCG, UCU, UCC, AGC, and AGU, which all code for the amino acid serine, we need to analyze what these codons indicate in the context of genetic coding.

### Step-by-Step Solution:

1. **Understanding Codons**: Codons are sequences of three nucleotides in mRNA that correspond to specific amino acids. In this case, UCA, UCG, UCU, UCC, AGC, and AGU all code for the amino acid serine.

2. **Degeneracy of the Genetic Code**: The fact that multiple codons (six in this case) can code for the same amino acid (serine) indicates that the genetic code is degenerate. This means that there are more codons (64 total) than there are amino acids (20), allowing for redundancy in the coding.

3. **Genetic Code Characteristics**: The genetic code is described as universal (it is largely the same across different organisms), and it is also degenerate (as explained). However, the presence of multiple codons for a single amino acid does not imply that all amino acids are coded by six codons; rather, it is specific to certain amino acids.

4. **Eliminating Incorrect Options**:
- **UCA as the Initiator Codon**: UCA is not the initiator codon; the start codon is AUG.
- **All Amino Acids Coded by Six Codons**: This statement is incorrect because not all amino acids have six codons; only some do.

5. **Conclusion**: The primary indication of the six codons coding for serine is that the genetic code is degenerate. This means that multiple codons can specify the same amino acid.

### Final Answer:
The codons UCA, UCG, UCU, UCC, AGC, and AGU indicate that the genetic code is degenerate.