Final answer:
RNA's four bases form codons of three nucleotides each, allowing for 64 combinations that code for 20 amino acids, exceeding the necessary amount and providing redundancy.
Step-by-step explanation:
The RNA molecule contains just four bases, which can seem insufficient to carry instructions for the 20 different amino acids that make up proteins. However, the genetic code operates on the principle of codons, which are sequences of three nucleotides. This three-nucleotide or triplet code allows for 4³ (64) possible combinations, exceeding the number necessary to encode all 20 amino acids.
For instance, the codon GGU specifies the amino acid glycine, while GUC specifies valine. Moreover, because of the redundancy of the genetic code, some amino acids are specified by more than one codon, ensuring that all 20 amino acids can be uniquely coded for by different combinations of nucleotides.