Origin of Life SC.912.L.15.8

Conditions on early Earth *Reducing atmosphere water vapor (H2O), CO2, N2, NOx, H2, NH3, CH4, H2S lots of available H & its electron no free oxygen Energy source lightning, UV radiation, volcanic low O2 = organic molecules do not breakdown as quickly * Are there alternative topics? What’s missing from that atmosphere?

Origin of Organic Molecules Abiotic synthesis 1920 Oparin & Haldane propose reducing atmosphere hypothesis 1953 Miller & Urey test hypothesis formed organic compounds amino acids adenine Oparin and haldane: energy from lightning and intense UV radiation (early oceans were a primitive soup Urey and Miller: teted this hypothesis

What is science? Uncovered jars Covered jars Controlled Variables: jars, type of meat, Location, temperature, time In a controlled experiment, only one variable is tested at a time. Redi designed an experiment to determine what caused the sudden appearance of maggots. In his experiment, the manipulated variable was the presence or absence of the gauze covering. The results of this experiment helped disprove the hypothesis of spontaneous generation. Copyright Pearson Prentice Hall

Manipulated Variable: Gauze covering that keeps flies away from meat Several days pass. Responding Variable: whether maggots appear Maggots appear. No maggots appear. Copyright Pearson Prentice Hall

Pasteur’s Test of Spontaneous Generation Louis Pasteur conclusively disproved the hypothesis of spontaneous generation. Pasteur showed that all living things come from other living things. Copyright Pearson Prentice Hall

Pasteur’ s Experiment Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms. Pasteur’s experiment showed that boiled broth would remain free of microorganisms even if air was allowed in, as long as dust and other particles were kept out. Broth is boiled Copyright Pearson Prentice Hall

The Impact of Pasteur’s Work Pasteur saved the French wine industry, which was troubled by unexplained souring of wine. He began to uncover the nature of infectious diseases, showing that they were the result of microorganisms. Copyright Pearson Prentice Hall

First Eukaryotes ~2 bya 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 Endosymbiotic theory Stromatolite: layered rocks that form when certain prokaryotes bind this films of sediment together DNA cell wall plasma membrane Prokaryotic cell Prokaryotic ancestor of eukaryotic cells Eukaryotic cell

Endosymbiosis Evolution of eukaryotes origin of chloroplasts Eukaryotic cell with mitochondrion 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

Review Questions

Review Questions

Review Questions