To determine which point mutation would result in the formation of a new protein, we need to compare the original and mutated codons to see if the amino acid they code for has changed. Let's analyze each provided mutation:
1. UCA to UCG:
- Original Codon: UCA (Serine)
- Mutated Codon: UCG (Serine)
- Both UCA and UCG code for Serine. Therefore, this is a synonymous mutation, which does not change the protein.
2. UAA to UAG:
- Original Codon: UAA (Stop)
- Mutated Codon: UAG (Stop)
- Both UAA and UAG are stop codons. Therefore, this is also a synonymous mutation, which does not produce a new protein.
3. UGU to UGC:
- Original Codon: UGU (Cysteine)
- Mutated Codon: UGC (Cysteine)
- Both UGU and UGC code for Cysteine. Hence, this is another synonymous mutation, resulting in no new protein.
4. UUU to UUA:
- Original Codon: UUU (Phenylalanine)
- Mutated Codon: UUA (Leucine)
- UUU codes for Phenylalanine, while UUA codes for Leucine. This is a non-synonymous mutation since the amino acid changes from Phenylalanine to Leucine, resulting in the formation of a new protein.
Thus, the point mutation that results in the formation of a new protein is:
UUU to UUA
So the answer is:
4
