A nucleic acids B DNA C double helix D DNA nucleotide E base pair F phosphate G deoxyribose H DNA base I DNA duplication J DNA polymerase K DNA purines L DNA pyramidines M guanine N cytosine O thymine P adenine Q RNA R RNA nucleotide S transcription T RNA polymerase U pre-messenger RNA V RNA base W ribose X ribosomal RNA Y transfer RNA Z messenger RNA AA tRNA activation BB amino acid CC activation enzyme DD RNA bases EE DNA bases FF RNA purines GG RNA pyramidines HH uracil