Lecture 1: Cells and the Central Dogma

Cells

• The fundamental unit of life

• Prokaryotes

  • Unicellular

  • Small and simple in appearance

  • Ex. Bacteria & Archaea

• Multicellular

  • Keep their DNA in a membrane-bound compartment called the nucleus

  • Larger and have more complex cytoskeletal networks

Prokaryotes

• Despite being individual, prokaryotic cells can interact with one another in a way that they’re almost multicellular communication

  • EXAMPLE: Bacillus subtilis biofilm

Domains of life

• Three main ones

  • Bacteria

    • Nonphotosynthetic bacteria

    • Photosynthetic bacteria

  • Eukaryotes

    • Plants

    • Animals

    • Fungi

  • Archaea

    • Archaea

Central dogma: Flow of genetic information

• DNA → RNA → Protein

Techniques used to study cells

• Microscopy

  • Light microscopy

    • Uses a light source to generate light which passes through a specimen to create an image

    • Can be used to look at live or fixed cells

  • Electron microscopy

    • Electrons pass through a specimen, which are then scattered

    • These interferences help create an image

    • Can ONLY be used to look at fixed cells

    • Ex. Fluorescence microscopy (like GFP)

      • Can be used to look at both live and fixed cells