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Evolution Darwin’s Ideas Hardy-Weinberg Evidence for Evolution Speciation and Mechanisms Origins
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There’s something you need to know…
The Origin of Species Mom, Dad… There’s something you need to know… I’m a MAMMAL!
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What must Earth have been like before living things took over?
Origin of the Earth What must Earth have been like before living things took over?
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The Primitive Earth Atmosphere:
All chemicals/compounds necessary are thought to have originated on earth Inorganic precursors: Water vapor Nitrogen Carbon dioxide Small amounts of hydrogen and carbon monoxide These were the monomers for forming more complex molecules. Experiments have shown that it is possible to form organic from inorganic.
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Origin of Organic Molecules
Water vapor Condensed liquid with complex, organic molecules Condenser Mixture of gases ("primitive atmosphere") Heated water ("ocean") Electrodes discharge sparks (lightning simulation) Water Origin of Organic Molecules Abiotic synthesis Oparin first molecules formed by strong energy sources Miller & Urey test hypothesis formed organic compounds amino acids adenine CH4 H2 NH3 Attempted to prove that chemical evolution could occur The experiment Used water, methane, ammonia, hydrogen sealed inside a glass container Water was heated to produce steam and sparks were generated from electrodes Water was then cooled and allowed to condense\ Experiment went on in this cycle for 1 week Results 15% of carbon was now present in the form of organic materials 13 out of 20 amino acids were present High concentrations of the base Adenine were also detected
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Key Events in Origin of Life
Origin of Cells (Protobionts) lipid bubbles separate inside from outside metabolism & reproduction Origin of Genetics RNA is likely first genetic material multiple functions: encodes information (self-replicating), enzyme, regulatory molecule, transport molecule (tRNA, mRNA) makes inheritance possible makes natural selection & evolution possible Origin of Eukaryotes endosymbiosis Life is defined partly by two properties: accurate replication and metabolism. Neither property can exist without the other. Self–replicating molecules and a metabolism–like source of the building blocks must have appeared together. How did that happen? The necessary conditions for life may have been met by protobionts, aggregates of abiotically produced molecules surrounded by a membrane or membrane–like structure. Protobionts exhibit some of the properties associated with life, including simple reproduction and metabolism, as well as the maintenance of an internal chemical environment different from that of their surroundings. Laboratory experiments demonstrate that protobionts could have formed spontaneously from abiotically produced organic compounds. For example, small membrane–bounded droplets called liposomes can form when lipids or other organic molecules are added to water.
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Timeline Key events in evolutionary history of life on Earth
3.5–4.0 bya: life originated 2.7 bya: free O2 = photosynthetic bacteria 2 bya: first eukaryotes
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Prokaryotic ancestor of eukaryotic cells
~2 bya First Eukaryotes Development of internal membranes create internal micro-environments advantage: specialization = increase efficiency natural selection! nuclear envelope endoplasmic reticulum (ER) plasma membrane infolding of the plasma membrane nucleus DNA cell wall plasma membrane Prokaryotic cell Prokaryotic ancestor of eukaryotic cells Eukaryotic cell
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internal membrane system
1st Endosymbiosis Evolution of eukaryotes origin of mitochondria engulfed aerobic bacteria, but did not digest them mutually beneficial relationship natural selection! internal membrane system aerobic bacterium mitochondrion Endosymbiosis Ancestral eukaryotic cell Eukaryotic cell with mitochondrion
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photosynthetic bacterium chloroplast & mitochondrion
Eukaryotic cell with mitochondrion 2nd Endosymbiosis Evolution of eukaryotes origin of chloroplasts engulfed photosynthetic bacteria, but did not digest them mutually beneficial relationship natural selection! photosynthetic bacterium chloroplast mitochondrion Endosymbiosis Eukaryotic cell with chloroplast & mitochondrion
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Theory of Endosymbiosis
Lynn Margulis Theory of Endosymbiosis Evidence structural mitochondria & chloroplasts resemble bacterial structure genetic mitochondria & chloroplasts have their own circular DNA, like bacteria functional mitochondria & chloroplasts move freely within the cell mitochondria & chloroplasts reproduce independently from the cell
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Cambrian explosion Diversification of Animals
within 10–20 million years most of the major phyla of animals appear in fossil record 543 mya
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