October 11th, 2022

Big Bang to Humankind

The Central Dogma

DNA → RNA (multiple types) → Proteins
 (transcription)         (translation)


DNA → mRNA transcript


mRNA → Protein

  • tRNA match to mRNA in chunks of 3 nucleotides.
    • Ribosomal RNA holds mRNA still so tRNA can find its match.
  • RNA maps to amino acids - multiple RNA chunks per amino acid, to be tolerant to possible mutations.
  • Amino acids link together via peptide onds.

Protein Structures

  1. Primary structure - amino acid chain (polypeptide)
  2. Secondary structure - folded structure within a polypeptide
  3. Tertiary structure - 3D structure of polypeptide
  4. Quartenary structure - multiple polypeptide chains joining together to make a protein When proteins are denatured, they go from quartenary structures to tertiary structures.


Traditional vaccines: have a bit of the virus (live or killed).

  • Example: smallpox is a live virus
  • We don’t use live virus much anymore

mRNA Vaccine for Covid: Injects mRNA transcript of Covid spike proteins.

  • Cells express it into a protein, immune system mounts a response.
  • Why mRNA vaccine for Covid?
    • Covid mutates/evolves very fast, so it’s hard to pin down one version to include in the vaccine.
    • Even a weakened version of the virus could be dangerous to immunocompromised people.
    • Because it’s a coronavirus, future mutations should also have the spike protein.