1. Unit 1 - The Origins of Life
Louis Pasteur
December 27, 1822 –
September 28, 1895

2. Pasteur’s swan neck flask

3. Pasteur’s sour wine

4. Radiometric dating of rocks (amîtsoq gneisses) from
The Earth Is Old!
Radiometric dating of rocks (amîtsoq gneisses) from
Western Greenland
Similar results from Australia, Wisconsin, Africa and Russia

5. Cyanobacterial microfossils

6. Extant stromatolites

7. Fossilized stromatolites

9. -Woese, Micro. Rev., 1987
The dilemma faced by microbiologist is that many bacteria look the same. It’s fairly to distinguish between the various plants and animals in a setting like this. But the two microbial species in these electron micrographs are all but indistinguishable.
In 1977 a fella by the name of Carl Woese at the Univerity of Illinois changed all that. By comparing the DNA of many different organisms he convincingly showed the biological world, rather than 5 kingdoms, was more appropriately divided into three domains of living things: the Bacteria, the Archaea and the Eukarya. (You are here - point to humans).
This is a phylogenetic tree. A tree of the similarity between the DNA of one organism and another. The shorter the distance between two organisms the more similar the DNA and by implication the more closely related they are.
Based on Dna evidence these two organisms are vastly different. More divergentt than plants are from animals.
One thing that you will note is that this tree does away with the hierarchy of the 5-kingdom scheme. The tip of each of these branches represents a living organism but it does not imply that one organism is more advanced than another - only genetically different. We’ll come back to this point in a couple of minutes.

10. Prokaryotes
Eukaryotes

17. Figure 3.8
The plasma membrane is a phospholipid bilayer with embedded proteins. There are other components, such as cholesterol and carbohydrates, which can be found in the membrane in addition to phospholipids and protein.
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18. Magnetosomes
Magentospirillum magnetotacticum

19. Eucaryotic nucleus & mitochondria

21. How diverse are the Archaea in the human mouth.