Question

a(n) is a three - letter code word in the genetic code.

Explanation:

In genetics, a codon is defined as a three - nucleotide sequence (which can be thought of as a three - letter code when considering the letters representing nucleotides, like A, T, C, G in DNA or A, U, C, G in RNA) that codes for an amino acid or serves as a start or stop signal in protein synthesis. This is a fundamental concept in molecular biology related to the genetic code.

Answer:

codon