What does the genetic code describe?

• A. The formation of ribosomes
• B. The process of DNA replication
• C. The structure of DNA
• D. The correspondence between nucleotide triplets in mRNA and amino acids in proteins

Answer: (D)

The genetic code describes how three-nucleotide sequences in mRNA specify which amino acids are incorporated into a protein. Each codon—a trio of nucleotides—maps to a particular amino acid (with some amino acids having multiple possible codons), and translation uses tRNA to bring the matching amino acids to the ribosome. The process begins at a start codon and ends at a stop codon, and the same codon-to-amino-acid mappings are used in nearly all organisms. This mapping is distinct from processes like ribosome assembly, DNA replication, or the chemical structure of DNA, which are involved in other cellular functions.