Evolution The Origins of Life I Cellular Life

Evolution The Origins of Life I. Cellular Life

Review-Questions About Our Origins How did the universe form? l How did our galaxy form? l How did the sun and Earth form? l How/where did life start? l How did all the life forms on Earth develop? l Where do humans come from? l

Review-What evidence is there for evolution? Fossils l Geologic l Age of the Earth l Anatomy and Physiology l Molecular (DNA, “primordial soup”) l

Review-What is evolution? l A changes in a species over time l process of biological change by which descendents come to differ from their ancestors.

What explanations are there for how life started on Earth? Christianity-God l Buddhism-no creator, world constantly recreates itself l Islam-Allah l Native Americans-mother, mother animals l Aztec-gods-5 births of suns l Bantu-Bumba vomitted up “life” and Planets l

Review-How was the Earth formed? l l l Our solar system (Sun and planets) formed from a rotating disk of gas and dust about 4. 6 billion years ago. 4 -3. 8 bya Earth cooled down and the impacts happened less Solar radiation and lightning produced energy for reactions on Earth Water vapor condensed and rain formed large bodies of water Presence of water allowed inorganic compounds to form organic molecules

Origins of Life Organic molecule hypotheses-(Miller-Urey and Meteorite Hypothesis) l Early cell structures-(Iron-sulfide, lipid membrane) l RNA-early genetic material l

Organic Molecule Hypotheses l Miller-Urey Experiment-Passed an electrical current through mixture of gases and created amino acids and nucleotides Meteorite Hypothesis-Meteorite that landed in Australia had 90 different amino acids, possible that aa were brought to Earth on meteorites l Question: What do amino acids make? l

Early Cell Structures Hypotheses l Iron-sulfide bubbles hypothesis-4 b. y. a, hot iron sulfide chimneys concentrated basic organic molecules in small space Lipid membrane hypothesis-lipid molecules can form spheres around organic molecules l Question: What do lipids make up? l

RNA as Early Genetic Material l RNA can chop and copy itself w/out enzymes l Short chains of RNA can form from inorganic molecules

Summary-Molecular Origins of Life Molecules create the structures for life. l Organisms are made of molecules. l Under the right conditions, nonliving molecules such as gases, lipids, amino acids, and nucleic acids can naturally form the structures of life. l

Summary Questions l What some of the different beliefs that various religions have on how life started on Earth? l In your own words explain one of the biological hypotheses on how life started on Earth.