Oct 17 th

1. Warm Up: Identify 2 living and 2 non-living things in the picture. Explain in detail what makes them classifies as such Which essential question is this addressing? Oct 17th Agenda: 1. Warm Up-check flashcards 2. Origins QQ#4 3. Lab Procedures Homework 1. Origins Notes #4 2. Study for Quiz New TOC#s #12-Origins QQ#4 (in class) #13-Origins Notes #4 (10/19) #14-Lab Procedures Flow Chart (in class)

2. Origins Discussion QQ#4 ORIGIN OF LIFE

3. QQ#1What do you know about how life started on earth?

4. I. Early Theories A.Spontaneous Generation - The hypothesis that life arises regularly from non-living things II. Experiments That Helped to Disprove Early Theories • Italian scientist, Francesco Redi (1730’s) 1. Hypothesis: Maggots arose from tiny, non-visible eggs laid on meat 2. Procedures: • Put pieces of meat in several jars • Leave half open to the air • Cover the other half with thin gauze to prevent entrance of flies

5. 3. Results: • After a few days, meat in all jars spoiled and maggots were found only on the meat in the uncovered jars

6. II. Experiments That Helped to Disprove Early Theories cont. B. French scientist, Louis Pasteur (1864) 1. Hypothesis: Microorganisms do not arise from nutrient broth 2. Procedures: • Place nutrient broth in a flask with a long, curved neck. (This permitted air to enter, but trapped dust and other airborne particles) • Boil the flask thoroughly to kill any microorganisms • Do NOT seal the open end of the flask • Wait an entire year before gathering results

7. 3. Results: • After a year, no microorganisms could be found in the broth! Pasteur then removed the curved neck, permitting dust and other particles to enter. In just one day, the flask contained microorganisms! Microorganisms had clearly entered the flask with the dust particles from the air

8. QQ#2Explain how we know spontaneous regeneration is wrong

9. III. Current Theories • The Formation of Complex Molecules 1. Procedures: Scientists have simulated the conditions of Earth’s early atmosphere, adding energy to simulate early sunlight and lightening 2. Results: • In a few days, a “soup” of molecules • formed, including several amino acids • (the building blocks of proteins) • b)Reactions such as these occur today near volcanic vents at the bottom of the sea!

10. III. Current Theories • The Formation of Complex Molecules 2. Collections of these molecules tend to gather together into tiny round droplets known as coacervates • In the laboratory, these droplets have been shown to grow and divide! • Coacervates are not living cells, but their existence suggests ways in which the first cell may have formed.

11. QQ#3Explain how the first cells may have come to exist

12. III. Current Theories B. The First True Cells • They were PROKARYOTIC • lacked nucleus • anaerobic(survived in absence of O2), • heterotrophs (cannot synthesize own food) that resemble types of bacteria alive today • Had RNA (not DNA) stored • the genetic information

13. III. Current Theories C. The Evolution of Photosynthesis • Early heterotrophs fed on organic molecules until the supply diminished • Natural selection favored organisms that could harness energy from an outside source and use it for food • At some point, a primitive form of photosynthesis evolved using H2S instead of H20 • The first autotrophs (synthesize their own energy) were commonplace approx. 3.4 bya and grew in layered formations called stromatolites Living stromatolites still exist in Shark Bay, Australia

14. QQ#4What is the difference between and autotroph and a heterotroph

15. IV. The Road to Modern Organisms A. Oxygen and Life • Modern photosynthesis using H2O evolved 2.2 bya • Oxygen was released into the atmosphere as a waste product • Oxygen was poisonous to early anaerobic organisms and most died off. Earth was transformed! Anaerobic bacteria such as these now live only deep within the ocean, deep in mud and in other places where the atmosphere does not reach. Organisms using Oxygen began to evolve and dominate the planet!

16. IV. The Road to Modern Organisms B. Eukaryotes and the Origin of Complex Cells 1. EUKARYOTIC organisms with a true nucleus, DNA and membrane-bound organelles evolved between 1.4 and 1.6 bya 2. Eukaryotic ancestors probably ingested bacteria that performed specific functions, later becoming mitochondria and chloroplasts

17. QQ#5Compare and Contrast prokaryotes and Eukaryotes

18. IV. The Road to Modern Organisms C. Sexual Reproduction and Multicellular Life • The origin of sexual reproduction rapidly increased the rate of early evolution • Genes and traits began shuffling and combining in ways they were not capable of before • Genetic variation created new species under the influence of natural selection!