1. Unit 8 Evolution

2. Carbohydrates – monosaccharides – Energy!
Review
Organic Molecules
contain carbon
Carbohydrates – monosaccharides – Energy!
Proteins – amino acids – enzymes, structure, transport, regulate
Lipids – fatty acids – Energy storage/insulation
Nucleic acids – nucleotides – store/transmit heredity info

3. Prokaryotic cells (bacteria) – no true nucleus; simple cells
Review
Prokaryotic Cells vs. Eukaryotic Cells
Prokaryotic cells (bacteria) – no true nucleus; simple cells
Eukaryotic cells – have nucleus; contain organelles; complex

4. Spontaneous Generation or Abiogenesis
Review
Spontaneous Generation or Abiogenesis
Before the invention of the microscope, it was a commonly held belief that life could come from nonliving things (matter).
“Vital forces” could bring about living things from nonliving material.
Maggots arose from meat
Mice arose from bags of grain
Beetle arose from dung

5. Experiments to disprove abiogenesis
Review
Experiments to disprove abiogenesis
1660’s – Francesco Redi
Set up jars of meat:
One set left open
One set tightly sealed
One set covered with gauze

6. Review
After several days
Maggots appeared on jars left open but were absent from sealed and covered jars

7. Experiments to disprove abiogenesis
Review
Experiments to disprove abiogenesis
1800’s - Louis Pasteur –
Designed a special curved-neck flask to finally disprove spontaneous generation.

8. Experiments to disprove abiogenesis
Review
Experiments to disprove abiogenesis #1
Boiled broth in curved-neck flask.
Broth remains free of microorganisms for a year. #2
Curved-neck is broken off
Broth becomes cloudy with microorganisms within 2 days.
This experiment finally disproved abiogenesis

9. BIOGENESIS – LIFE CAN ONLY COME FROM OTHER LIVING THINGS
CURRENT THEORY – ALL CELLS COME FROM PRE-EXISTING CELLS.
LIFE CANNOT SPONTANEOUSLY GENERATE!

10. Temperature- Very hot, no water initially
Earth’s Early History
4.6 billion years ago (bya)
Temperature- Very hot, no water initially
Very volatile gases in the atmosphere. (CO2, CO, Hydrogen cyanide, Nitrogen, Hydrogen sulfide)
NO OXYGEN IN ATMOSPHERE!

11. How did life arise?
1924 – Aleksandr Oparin hypothesized that organic compounds can be produced from inorganic early atmosphere with electricity (lightning)

12. How did life arise?
1950’s – American scientists Miller and Urey tried to recreate the atmosphere of the earth in a lab setting

13. Miller and Urey
Set up experiment with boiling water and gases (methane, ammonia, hydrogen gas)
Sparked with electricity to simulate lightning and sun’s energy on early Earth.
Cooled mixture to cause condensation. Results: After a few days, they obtained amino acids!

14. Evolution of Organisms on Earth
First cells did not use Oxygen, but could not make their own food. So they were
Anaerobic Heterotrophic Prokaryotics
(bacteria, did not use oxygen)
Autotrophic Prokaryotes eventually evolved which produced Oxygen (bacteria, photosynthetic)
Eventually, Aerobic Eukaryotic Cells arose
(cells with nucleus, used oxygen)

15. ENDOSYMBIOTIC THEORY
Endosymbiotic Theory says that eukaryotic cells arose from communities of prokaryotic cells living together.
Symbiosis = relationship (Endo=into)

16. Endosymbiosis
Ancient prokaryotes may have entered primitive eukaryotic cells and remained there as organelles.
Mitochondria and chloroplasts share many features of prokaryotic cells.