Chapter 14 History of Life

Origin of Life Spontaneous Generation — Life from nonlife Francesco Redi — (1626-1697) Meat Covered meat Maggots No maggots

Lazzaro Spallanzani— (1729-1799) Uncovered Broth Covered Broth Cloudy Broth Unclouded Broth Cloudiness comes from microorganisms

Louis Pasteur—(1822-1895) Flask: Tilted flask: S shaped neck S shaped neck No microorganisms Microorganisms Biogenesis - Life comes from Life

Earth’s History 5 billion years ago the earth was formed 3.9 billion years ago the oldest rocks were formed 3.5 billion yeas ago the first fossils formed

Fossils Fossils - most formed from hard part of body - shell, bones, teeth may be trapped in resin (sap) or ice, tar, mud Three types of fossils: 1. Imprints –film of carbon remains 2. Molds - impression of object 3. Casts - sediments fill a mold http://web.ukonline.co.uk/conker/fossils/what-is-a-fossil.htm

Molds - impression of object Position in sedimentary rock

Dating Fossils Position in sedimentary rock Carbon 14 dating—1/2 life of C-14, 5700 years Ratio of C-12/C-14 is constant Ratio when an organism dies same as atmosphere when it died, makes it possible to date thing up to 50,000 years old Potassium & Uranium dating - longer ½ life makes it possible to date objects older than 50,000 years old

First Organic Compounds Alexander Oparin — (1894-1980) Theorized that the original atmosphere of the Earth consisted of NH3 (ammonia), H2 (hydrogen gas), H20 Water Vapor, and compounds made of Carbon & Hydrogen. Lightening and the heat of the Earth created simple organic molecules Miller & Urey - Tested Oparin’s theory p.285 - produced simple organic compounds supporting the theory

First Organisms First Prokaryotes – 1 celled organism with no nucleus Anaerobic — no 02, Autotrophic make own food, or heterotrophic Endosymbiosis Theory- Lynn Margulis (I938-) Several prokaryotes lived together in symbiotic relationship = first eukaryotes p. 290