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Evolution Evolution Thales- Everything stemmed ultimately from Water. Idea of descent with modification? Aristotle- Everything has a desire to move from lower to higher forms. How did life develop such a diversity of forms on Earth? The prevailing perception in the Dark and Middle Ages in Europe was that all things on Earth had existed in basically their same forms since they were created. Pierre Louis Maupertuis-1750 Small Changes between generations could accumulate into large changes given enough time. Fossils Example: Trilobite From 550 Million Years Ago! Water protects organism for decomposition Bacteria eat soft parts and leave exoskeleton An organism that is deposited in sediments after death is covered by additional sediments that protect it from predation and decay. Over time, the weight of additional sediments squeeze out the fluids from the organism and the sediments that surround it, causing lithification (sedimentary rock formation). Charles Lyell Advocated Uniformitarianism. Believed in an old Earth. The time frame given by an old Earth would allow for Evolution Evolution Voyage of the Beagle Finches Origin of the Species • “There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” Tree of Life Cells Thermodynamics First Law-The amount of energy in the Universe remains constant Second Law-The Universe tends towards a state of disorder. Basic Metabolic Needs 1. A source of raw materials with which to build new products. For a cell- key raw materials are molecules that provide the cell with carbon and other basic elements for life Basic Metabolic Needs 2. A source of energy This fuels the metabolic processes that break down old molecules and manufacture new ones. Metabolic Classifications Carbon SourcesHeterotroph- ‘others’ and ‘feed’. Autotrophes- ‘self’ and ‘feed’ Energy Sourcesphoto- ‘from light’ chemo- from chemicals’ Metabolic Classifications Photoautotrophs Chemoautotrophs Photoheterotrophs – Chemoheterotrophs - ATP and ADP Biochemical Processes Earth Life is Carbon-Based CARBON- What is the big deal? Organic Molecules Silicon-Alternative to Carbon? Although can also bond with 4 atoms at a timethe chemical bonds formed are weaker than those for Carbon Molecular Components of Cells • Carbohydrates– make important cellular structures – Store energy • Lipids– Can form barriers that make it possible for cells to exist (Cell Membrane!) – Store energy Proteins Enzymes-serve as catalysts for biochemical reactions. Evidence for a Common Ancestor Evidence of Single Common Ancestor: 1. All Life uses the Left Handed Version of Amino Acids 2. All Life uses only 20 amino acids 3. All Life uses ATP Nucleic Acids DNADeoxyribonucleic RNARibonucleic DNA->Genes->Chromosomes Amino Acids-building Blocks of Proteins AMINO ACIDS Handedness(Chirality) Tree of Life Mutations The Molecular Basis of Evolution 1. Mistake in Replication 2. Exposure to Radiation 3. Exposure to Carcinogens