Nucleic Acids

1. 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)

2. 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

3. 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’!