Lecture 1- Wednesday, January 22, 2003 R. Jones
Read Chapter 15.14, 16-16.6; 34-34.9
The Earth, the biosphere, and origins of life:
1. Origins of the Universe: Galaxies and Stars. 100 bn stars in our galaxy, the Milky Way
2. Earth: 80% covered by oceans, 10% by mountains, deserts and ice/water. Only 20% of earth's land is used for agriculture
3. The Biosphere: That part of earth that harbors living things. Extends up to 8-10 Km from earth's surfave and about 10 m in soil. All parts of oceans, even the deep oceans harbor living organisms.
4. Origins of life: The timetable: Earth solidified about 4-4.5 BYA. Evidence that life existed 3.5-4 BYA comes from the finding of fossils in ancient rocks. Cyanobacteria found in fossils that are 2.5-3 BYA. Eukaryotes appeared 1.5 BYA and multicellular organisms 600 MYA
5. Early ideas on the Origins of Life: spontaneous generation and Louis Pasteur. Swan flasks and proof that sterile media do not become contaminated as a result of spontaneous generation.
6. Chemical evolution: Based on the hypothesis of Haldane and Oparin that the early atmosphere of the earth had no oxygen and was thus a "reducing atmosphere" that alos contained hydrogen, nitrogen, ammonia, carbon monoxide, methane etc. Water was abundant and energy in the form of heat, light and electricity was also present.
7. Miller and Urey- experimental testing of Haldane-Oparin concept. Built an apparatus and showed in the laboratory that when the presumed ancient atmosphere was duplicated, energy inputs could cause more complex moleules to be formed from simple molecules.