Hint: Proline is a proteinogenic amino acid, which is often encoded by a triplet codon having the same pyrimidine in the first two places. This nitrogenous base is found in both DNA (deoxy ribonucleic acid) as well as RNA (ribonucleic acid).
Complete answer:
A genetic code is a triplet codon that encodes for a specific amino acid. There are a total sixty four codons that are found in all organisms of the three domains and are formed by a combination of any three nucleotides among adenine (A), guanine (G), uracil (U) or cytosine (C). Hence, these sixty four codons are universal genetic codes. Three codons among the total genetic codes are stop codons that do not encode for any amino acids. Only sixty one genetic codes are capable of encoding twenty different amino acids.
Proline is one of twenty known amino acids, and is encoded by codon(s) present among sixty four universal genetic codes. There are four genetic codes or triplet codons that are mainly responsible for encoding for proline. The triplet codon has cytosine (C) in their first two places, whereas the third place is occupied by all four nitrogenous bases that are commonly found in RNA. Hence, the codons encoding for proline generally include CCG, CCA, CCU, and CCC.
The correct answer is option A, which includes CCC, CCG, and CCU.
Note: One amino acid may be encoded by single or more than one genetic code. For example – Methionine is an amino acid encoded by only one out of total sixty four genetic codes. However, proline (single amino acid) has four codons for its synthesis.
