DNA and RNA

• Nucleic acids: biomacromolecules made out of monomers called nucleotides.
• Nucleic acids have 2 natural forms: DNA and RNA.
• Structures of DNA and RNA:

  1. 4 Nitrogenous bases
  2. DNA: adenine (A), Thymine (T), Guanine (G), Cytosine (C)
  3. RNA: all the same except for Thymine; RNA has Uracil (U)
  4. A and G are purines -> two-fused carbon rings
  5. C and T are pyrimidines -> single carbon-nitrogen rings
  6. Sugars
  7. DNA: deoxyribose
  8. RNA: ribose
  9. Phosphate groups
  10. Can have up to 3 phosphate groups; nucleotides lose 2 PO4 groups when they join the growing DNA/RNA chains.
• A polynucleotide chain has directionality -> 2 chemically distinct ends. At the 5' end, the phosphate group is attached. At then other end, 3' end, the 3' hydroxyl is exposed.

  REMEMBER! The 5' end is the beginning and the 3' end is the end.
• DNA/RNA strands grow through the joining of the sugars between their neighbors by a set of bonds called a phosphodiester linkage.