The sugar-phosphate backbone forms the structural framework of nucleic acids, like DNA and RNA, and is composed of alternating sugar and phosphate groups.

It is an ester-derived prodrug that is converted in vivo by serum and tissue esterases to tenofovir, an acyclic nucleoside phosphonate (nucleotide) that inhibits HIV reverse transcriptase.

Definition. A section of DNA that encodes for a certain trait. A variant form of a gene. Role. Genes determine individual traits. Alleles contribute the diversity in phenotype expression. Determines .