October 6th, 2022

Big Bang to Humankind

  • DNA has a double helix shape, with bas pairs (A, T, C, G) joined by hydrogen bonds.
  • RNA is single stranded
    • Can form a double helix by itself, but usually doesn’t.
  • 3 main parts of DNA and RNA:
    • phosphate linking group
    • nucleic acid base → reflects changes of A/T/C/G
    • sugar group
  • Differences between DNA and RNA:
    • RNA uses Uracil instead of Thymine
      • They’re chemically very similar
    • DNA has H at 2’, RNA has OH at 2’
  • Nucleotides link via a condensation reaction (produces H2O) between phosphate and sugar (sugar-phosphate backbone).
  • Why do we have both DNA and RNA?
    • DNA is much more stable.
    • Lack of oxygen in DNA makes it energy intensive to replicate.
      • But DNA can still self-replicate.
  • RNA World hypothesis: all genetic information was once stored in RNA.
    • Start simple and evolve to be more complex.
    • This was during pre-cellular times.