What is a letter in a gene combination?

A letter in a gene combination represents a specific nucleotide base in the DNA sequence. In genetics, these letters correspond to the four bases: adenine (A), thymine (T), cytosine (C), and guanine (G). The arrangement of these letters forms the genetic code that determines traits and functions in an organism. For example, a gene combination like "ATCG" indicates a specific sequence of nucleotides that encodes for particular biological information.