Australian Year 10 Biology Practice Test

The genetic code is read three letters at a time because each set of three nucleotide bases in DNA or RNA, known as a codon, corresponds to a specific amino acid in protein synthesis. This triplet nature of the genetic code is crucial for accurately translating the genetic information into functional proteins.

When the ribosome reads the mRNA, it does so in blocks of three bases, ensuring that the correct amino acids are assembled in the proper order to form proteins. This system provides a sufficient range of combinations, allowing for 64 possible codons (4 different nucleotides each contributing to three positions: \(4^3 = 64\)), which includes codons for all 20 standard amino acids as well as stop signals that mark the end of protein synthesis.