Packet 11- Evolution Notes: pg. 1

Notes: History of Life on Earth This experiment was done with an apparatus like the one seen above, to the left. In it they simulated the conditions present about 3.5 billion years ago on Earth. Several scientists showed how it may have been possible for __________________ (in the right conditions) to evolve to spontaneously form _______________________ This was very important since organic compounds are the building blocks of all _____, the basic unit of life. organic compounds inorganic compounds cells

What are Organic and Inorganic Compounds? Organic: compounds that contain Carbon, the building blocks of life Inorganic: compounds without carbon

Miller and Urey Experiment Attempted to explain formation of first organic compounds. Simulated conditions of Primitive Earth Sealed inorganic gasses in a chamber without oxygen and simulated lightening(which acted as a heat source in early Earth) After one week, amino acids had formed. Are amino acids organic compounds?

What were some theories about where life came from? This idea of life coming from life is called_______________. While it is supported today, many once believed that living things could arise from the non-living- a theory called ______________ or spontaneous generation. biogenesis abiogenesis It was believed that living things could spontaneously appear due to a vital force.

Lets break it down… A= not/without Bio= life Gen= give birth

Once the first cells formed- they evolved ( from simple to complex) 1st- Anaerobic Prokaryotes- there was only a little free oxygen (O2) on primitive Earth , so the first life forms had to be anaerobic. Heterotrophs (feeders) came before  autotrophs (producers….food and oxygen) 2nd- Aerobic prokaryotes, which thrived in the oxygen rich environment (thanks to the autotrophs).

3rd- Eukaryotes- Complex cells with a nucleus and membrane bound organelles (see the diagram below of the theory of Endosymbiosis) Evolution of mitochondria from aerobic endosymbionts Evolution of chloroplasts from photosynthetic endosymbionts Ancestral Prokaryotes Evolution of the nucleus

Endosymbiotic Thoery

What is the cell theory? According to the cell theory, “All cells come from preexisting cells” Binary fission (bacteria) Mitosis (body cells) Meiosis (reproductive cells)

You have 15 minutes to work on pg. 2 Skip #6-10 unless you remember them 

History of Life Overview 1. The early atmosphere had little of this type of gas oxygen and therefore the first organisms must have been anaerobic. 2. Using a closed system, Miller and Urey were able to show that organic compounds could from inorganic compounds, under the right conditions. 3. The earliest life forms on earth appeared about 3.5 billion years ago.

History of Life Overview 4. The theory that living things come from non-living things is called abiogenesis. 5. The idea that living organisms only come from other living organisms is biogenesis.

History of Life Overview 6. Cenozoic Era B. When man is first believed to appear on the planet, present era. 7. Paleozoic Era A. Increasing diverse life form, first fish appears 8.Mesozoic Era D. Small mammals appear, dinosaurs appear and disappear. 9. Precambrian Era C. First life forms (prokaryotes) appear, also the longest era

History of Life Overview 10. List the eras in order (beginning with the first and ending with the current era). Precambrian Paleozoic Mesozoic Cenozoic

History of Life Overview 11. The endosymbiont theory attempts to explain the formation of eukaryotic cells from several prokaryotic cells that formed a mutually beneficial relationship. 12. Compare biogenesis to abiogenesis. (What do they have in common?) They both attempt to explain the origin of life.

History of Life Overview 13. Contrast biogenesis to abiogenesis. (How are they different?) Biogenesis says life came from life Abiogenesis says life comes from non-living

History of Life Overview 14. Distinguish between the terms aerobic and anaerobic. Aerobic requires oxygen, anaerobic does not.

History of Life Overview 15. Explain why scientists believe that the first life forms would have been anaerobic. Because there would have been little or no oxygen present in primitive earth.