Prokaryotes and Eukaryotes

Cell Theory and Prokaryotes vs. Eukaryotes

What is a Cell?

  • Cell – Basic unit of living things.
  • Organisms are either:
    • Unicellular – made of one cell such as bacteria and amoebas.
    • Multicellular – made of many cells such as plants and animals.

Cell Theory

  • Confirmed discoveries that all scientists believe to be true about cells:
    • Cells are the basic unit of life.
    • All living things are made of cells.
    • New cells are produced from existing cells.

The Discovery of Cells

  • Prokaryotic:
    • before nucleus
    • No defined nucleus
    • No organelles
    • Free DNA
  • Eukaryotic:
    • true nucleus
    • Organelles present

Prokaryotes

  1. NO nucleus
  2. NO membrane bound organelles (just ribosomes)
  3. ALL are unicellular
  4. Smaller than eukaryotic cells
  5. Forerunner to eukaryotic cells (smaller and more simple)
  6. DNA – single chromosome, double stranded and circular
  7. Ex: ALL Bacteria and Archaea

Eukaryotes

  1. Has a nucleus with a nuclear envelope
  2. Bigger and more complex than prokaryotes
  3. Have membrane bound Organelles (golgi, ER, lysosomes…etc)
  4. DNA – double-stranded and forms chromosomes (highly organized)
  5. Can be uni- OR multicellular organisms
  6. Ex: animals, plants, fungi

Similarities

  1. Contain all four biomolecules (lipids, carbs, proteins, and nucleic acids)
  2. Have ribosomes
  3. Have DNA
  4. Similar Metabolism
  5. Can be unicellular (But doesn’t have to be for Eukaryotes)
  6. Have cell/plasma membranes or cell wall