These four "letters" are A, C, G, T, which are the first letters of the chemicals that make the links of Adenine, Cytosine, Guanine, and Thymine known as nucleotides.
Lezi "zinhlamvu" ezine ngu-A, C, G, T, okuyizinhlamvu zokuqala zamakhemikhali enza izixhumanisi Audine, Ci-ytosine, Gi-uanine, ne- Ticulo elaziwa ngokuthi yi-nucleotides.