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History of life notes Theory = Early Earth 4.6 bya - VERY (colliding meteorites, erupting volcanoes) - Atmosphere was mostly nitrogen, carbon dioxide, water vapor, methane, ammonia but _____________________________!!! 4.4 bya - Earth ____________ - water vapor condenses into ________ creates oceans (where the first life will form) Evidence that we do have! Fossils = (Examples: A person who studies fossils is called a__________________ (just like Ross on Friends!) How is a fossil made? - after an organism is buried, the sand and clay around it harden to form_________________________. Then erosion brings the fossil to the surface Dating Fossils 1. Relative Dating- older rocks/fossils are on the ________ younger ones are on top 2. Absolute Dating (also called radiometric dating)- measures the amount of ___________ substance left in the rock or organism and determines its actual age By examining rock layers and dating the fossils, scientists have been able to put together a chronology, or calendar of Earth’s history called the____________________________. (see left page) Origin of Life Cell Theory 1. all living things are made of ________ 2. cells are basic unit of _______________ & ________________ 3. All cells come from pre-existing cells. What is the big question this theory raises? 1. 2. - The initial belief was that life was created through _______________________ (abiogenesis). Example: Summary History of life notes Disproving Spontaneous Generation 1. Francesco Redi was the first to disprove spontaneous generation in the 1600s. Although Redi was able to disprove that large organisms did not simply appear, many scientists thought that microorganisms (bacteria) were so numerous and widespread that they must arise spontaneously- probably from a vital force in the air. 2. Louis Pasteur in the mid 1800’s designed an experiment that disproved the spontaneous generation of_____________________________. From this time on________________________ , the idea life comes from life holds true. (Ex. Humans give birth to humans, mice to mice, etc.) Summary History of life notes But…. How did the very first life form that start this chain reaction?!!! The current theory is that life began in the_____________________. Oparin’s hypothesis: Energy from the _______________________________________ triggered chemical reactions with the vapors that were present in the early atmosphere to produce__________________________________________ . Then, the rain washed the molecules into the _____________ to create what is called the _____________________ (place of the origin of life). PROOF?? 1953- Stanley Miller and Harold Urey tested the hypothesis by simulating the conditions of early Earth in a lab. Simple Molecules to Complex molecules? - experiments were done to prove that simple molecules like ____________________ when heated without oxygen link up to form_________________ (complex molecules) Complex Molecules to Cells? - Sidney Fox showed how amino acid chains will form _____________________ Evolution of Cells 1st cells = 2nd cells = 3rd cells = Summary History of life notes First organisms were prokaryotes 2 types – Archaebacteria – bacteria that live in ____________________, and more closely related to early prokaryotes – EubacteriaEndosymbiotic theory Pre-eukaryotic bacteria engulfed another – (similar to mitochondria or chloroplast) Eukaryotic organisms formed much __________________ than prokaryotes Summary