Nucleic Acids

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Nucleic Acids• DNA: deoxyribonucleic acid; found in cells (except for rbc); contain genetic information in segments called genes; DNA is a “blueprint” for an organism. One gene codes for one protein. • RNA: ribonucleic acid; also found in cells (except for rbc); responsible for transmitting and expressing the genetic information of DNA by translating DNA into proteins. The proteins are the “doers”. Structure of Nucleic Acids:• Nucleoside:

– A 5 membered cyclic sugar unit + cyclic nitrogen containing base (pyrimidine and purine bases)

• Nucleotide:– A 5 membered cyclic sugar unit + cyclic nitrogen containing base + phosphate (a nucleoside and phosphate unit linked via a phosphate ester bond)

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Nucleic Acids• Naming nucleosides:

– Prefix deoxy- if sugar is deoxyribose

– No prefix if sugar is ribose

– Base name –ending, +osine (for purines)

– Base name –ending, +idine (for pyrimidines)

• Naming nucleotides:

– Name nucleoside + monophosphate, diphosphate or triphosphate

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Nucleic Acids• Polynucleotides: The –OH of C-3 forms a phosphate diester linkage with the phosphate of C-5. The free phosphate group is the 5’ end; the free –OH group is the 3’ end.• Just as the amino acid order is important in proteins, the order of the nucleotides in nucleic acids is significant; 3’ TAG 5’ is not the same as 3’ GAT 5’!