1. Origins of Life

2. Early Ideas
I. Spontaneous Generation:(not rejected until the mid 1800s) -life arises from non living material -Francesco Redi, an Italian scientist, in 1668 tested the idea that flies arose spontaneously from rotting meat. (scientific community not all convinced)

3. Early Ideas Theory of Biogenesis:
Living things can only produce living things
Louis Pasteur designed an experiment to show that biogenesis was true even for microorganisms

4. Modern Ideas: Miller-Urey experiment
Simple molecule formation:
1943 Stanley Miller and Harold Urey: Miller-Urey experiment
Add the picture to your notes and list the steps in their experiment
(watch video)Miller Urey Video

5. Modern Ideas: Miller-Urey experiment
Purpose: demonstrate the formation of simple organic molecules from inorganic compounds Results: Experiment produced several amino acids- suggested that early earth had substances that could produce organic compounds and then living things.

6. Modern Ideas
Once amino acids were formed, proteins are needed for life- scientists think clay particles could hold AA together to form proteins
Early genetic material-RNA
Scientists are working to
Discover how organic molecules
Became cells

7. Cellular evolution First cells were probably prokaryotic
Archaea (modern prokaryotes) are probably the closest relatives of modern cells
Cyanobacteria-primitive prokaryotes-autotrophs-produced oxygen to form ozone layer-alters conditions on earth for eukaryotic cells to survive

8. Endosymbiont Theory
1966, Lynn Margulis, ancestors of eukaryotic cells lived in association with prokaryotic cells-possibly inside-developed mutually beneficial symbiotic relationship
Evidence:
mitochondria and chloroplasts have their own DNA and ribosomes similar to prokaryotic ribosomes
Mitochondria and chloroplasts reproduce by fission (like prokaryotic cells)
View: Endosymbiont Theory-Concepts in Motion (online text)

9. Endosymbiont theory