Ch. 12 Notes History of Earth

1. Ch. 12 NotesHistory of Earth By: Brianna Shields January 9, 2006

2. Radiometric Dating Radioisotope Half-life Microsphere Fossil Cyanobacteria Eubacteria Archaebacteria Endosymbiosis Protist Extinction Mass Extinction Mycorrhizae Mutualism Arthropod Vertebrate Continental Drift List the terms in your vocab notebook, leaving about 3-4 spaces between each term

3. DO NOW • The first genetically engineered organism involved the transfer of a gene from what organism to bacteria? • What type of organism was the first to be cloned in its entirety? • Which type of test uses blood, semen, hair or bone to determine whether an individual was present at the scene of a crime?

4. GOALS • Summarize how radioisotopes can be used in determining Earth’s age • Compare two models that describe how the chemicals of life originated • Describe how cellular organization might have begun • Recognize the importance that a mechanism for heredity had to the development of life • Distinguish between the two groups of prokaryotes • Describe the evolution of eukaryotes • Recognize the evolutionary advance first seen in protists • Summarize how mass extinctions have affected the evolution of life on Earth • Relate the development of ozone to the adaptation of life to the land • Identify the first multicellular organisms to live on land • Name the first animals to live on land • List the first vertebrates to leave the oceans

5. Age of Earth 1. Fiery ball of rock 2. Surface of Earth cooled 3. Water vapor in air condensed to form ocean water How did Life Begin?

6. Measuring the Age of Earth Radiometric Dating- estimates age by measuring amount of radioactive isotopes How did Life Begin?

7. Measuring the Age of Earth Radioactive Isotopes Unstable forms of an element with varying masses Break down, give off large amounts of charged energy particles (radiation) How did Life Begin?

8. Measuring the Age of Earth Radioactive Decay Breakdown of radioactive isotopes into smaller, more stable ones Half-Life Time it takes for one half of a certain amount of radioisotope to decay How did Life Begin?

9. Measuring the Age of Earth Age determined by measuring amounts of remaining isotopes and their decay products How did Life Begin?

10. Formation of Life’s Chemicals Nonliving matter was energized by sun and volcanic heat Caused chemical reaction to produce simple organic molecules Organics became more complex First cells developed How did Life Begin?

11. Primordial Soup Model by Miller and Urey Earth’s oceans once filled with organic molecules (“soup”) No oxygen in air: only nitrogen, hydrogen, water, ammonia, methane Solar radiation, volcanic eruptions, lightning excited electrons in gases Electrons reacted with H in air to form organic molecules How did Life Begin?

15. Testing Miller and Urey’s Theory Apparatus with hot liquid water at bottom, hot gaseous mixture at top Electrical spark (“lightning”) added Found complex amino acids, fatty acids in chamber How did Life Begin?

17. Reevaluating Miller and Urey’s Theory Mixture of gases in their experiment couldn’t have existed No ozone layer, UV rays would hit planet destroying all ammonia and methane Without these, no biological molecules could be made Chemicals of life aren’t in air, they’re in water How did Life Begin?

19. Bubble Model Ammonia & methane gas bubbles formed underwater by volcanoes Bubbles protect gases from UV rays- chemical reactions occurred Bubbles rise to ocean surface, releasing organic molecules Molecules carried by wind, exposed to UV and lightning Organics become more complex, fall back into ocean, cycle continues How did Life Begin?

20. Bubble Model

21. Precursors of the First Cells Haven’t yet made proteins or DNA spontaneously in water in the lab (very difficult!) Have made short chains of RNA RNA- catalyst and info storage First self-replicating info Assembled first proteins How did Life Begin?

22. Precursors of the First Cells First step towards cells Microspheres: short amino acid chains that gather into tiny droplets in water (like oil in water) Similarities to cell membranes How did Life Begin?

23. Precursors of the First Cells First step towards cells Coacervates- short chains of linked amino acids and sugars that form tiny droplets in water How did Life Begin?

24. Assessment One • Explain how radioisotopes are used to determine the age of a rock. • Critique two scientific models that explain the origin of life. • Describe the first step that may have led toward cellular organization. • Explain how heredity may have arisen. • Miller and Urey’s model is inconsistent with the finding that Earth’s early atmosphere lacked which gas?

25. Evolution of Prokaryotes Fossil- preserved remains (bone, tooth, shell) or imprint of an organism from long ago How did Life Begin?

26. Evolution of Prokaryotes Oldest fossils - photosynthetic prokaryotes (cyanobacteria) 2.5 billion years old Released oxygen into oceans Oxygen eventually escaped into air How did Life Begin?

27. Evolution of Prokaryotes Eubacteria Cell walls contain peptidoglycan Cause disease and decay How did Life Begin?

28. Evolution of Prokaryotes Archaebacteria Cell walls lack peptidoglycan Unique lipid cell membranes How did Life Begin?

29. Evolution of Eukaryotes Eukaryotes Larger More Comples Internal Membranes DNA in a nucleus Mitochondria Chloroplasts How did Life Begin?

30. Evolution of Eukaryotes Theory of Endosymbiosis 1. Mitochondria are descendants of symbiotic, aerobic eubacteria 2. Chloroplasts are descendants of photosynthetic eubacteria How did Life Begin?

31. Evolution of Eukaryotes Theory of Endosymbiosis 3. Bacteria entered large cells as prey or parasites 4. Bacteria began to live there 5. Bacteria evolved into mitochondria or chloroplasts How did Life Begin?

34. Evolution of Eukaryotes Similarities between mitochondria, chloroplasts and bacteria Size Double Membrane on outside Circular DNA (contain genes different from actual cell) Ribosomes Reproduce through fission (independent of host cell’s cycle) How did Life Begin?

35. Multicellularity First kingdom- Protist Half earth’s biomass In multicellular organisms- specialized cells carry out different jobs Ex: Protection, reproduction, movement Protists evolved into multicellular fungi, plant and animal kingdom How did Life Begin?

36. Origins of Modern Organisms A. Cambrian Period (540-505 million years ago) Time of great evolutionary expansion 1909- Burgess Shale in Canada (major fossils of this period found) How did Life Begin?

38. Origins of Modern Organisms B. Ordovician Period (505-438 million years ago) Many different animals continued to thrive How did Life Begin?

39. Mass Extinctions A. Extinction- Death of all members of a species How did Life Begin?

40. Mass Extinctions B. Mass Extinction- Episode during which large numbers of species become extinct Five major events in history How did Life Begin?

42. Mass Extinctions C. Most devastating- end of Permian period 245 million years ago 96% of all species became extinct Cause may have been worldwide geological and weather changes How did Life Begin?

43. Mass Extinctions D. Fifth mass extinction 2/3 of all land species (including dinosaurs) become extinct How did Life Begin?

44. Mass Extinctions E. A sixth mass extinction event? May be currently occurring due to destruction of tropical rain forests by human activity How did Life Begin?

47. WEBSITES • ajkf

48. Assessment Two • Contrast the two major groups of prokaryotes • Analyze Margulis’s theory of endosymbiosis, citing its strengths and weaknesses • Compare bacteria with eukaryotes • Summarize how multicellularity advanced the evolutin of protists • Justify the argument that today’s organisms would not exist if mass extinctions had not occurred • The kingdom that includes both multicellular and unicellular eukaryotes is called?

49. DO NOW • 1. Which theory attempts to explain the evolution of mitochondria and chloroplasts? • 2. Which kingdom contains both multicellular and unicellular eukaryotes? • 3. Which mass extinction do we think is currently occurring?

50. Ozone Layer Enabled life forms to leave the ocean that protected them from harmful UV rays Photo. Cyanobacteria releases oxygen that reacted with sun to form ozone Ozone accumulated into a layer to protect Earth from UV radiation How did Life Begin?