Section 14.2 Cheet Sheet
Spontaneous generation – The idea that living material comes from nonliving material.
Was disproved by Francesco Redi and Louis Pasteur
Redi did the meat/fly experiment
Pasteur did the broth experiment
Biogenesis – Life comes from life
Simple organic molecules must have been formed on early Earth for life to arise.
Water vapor, carbon dioxide, nitrogen, and methane and ammonia in the atmosphere may have joined together via energy from the sun, lightning, and Earth's heat to form organic molecules.
These molecules would “brew” in a “primordial soup” until simple life arose called protocells.
Stanley Miller and Harold Urey tested the hypothesis and created organic molecules.
The first life might have been heterotrophs, eating organic molecules found in the oceans, and anaerobic, because there was not an abundant amount of oxygen in the atmosphere.
After all the food had been devoured by these heterotrophs, autotrophs would be favored by natural selection and would have evolved, called archaebacteria. These autotrophs would be photosynthetic, producing oxygen.
These autotrophs increased the concentration of oxygen in the Earth's atmosphere and allowed aerobically energy producing organisms to evolve.
Lightning also may have converted much of the oxygen in the atmosphere to ozone, forming a shield from the dangerous ultraviolet radiation from the sun, which enabled more complex organisms to evolve.
Lynn Margulis proposed a theory for how eukaryotes may have evolved, called the endosymbiont theory.
Mitochondria evolved from energy making bacteria.
