-
Redi
Francesco Redi put decaying meat in some jars, then covered half of them. When maggots appeared only on the uncovered meat, Redi explained that they had hatched from fly eggs left by circulating flies. Link text -
Needham
John Needham heated broth in flasks (thinking he had killed all life forms within the flask). After waiting some time he observed microorganisms and he explained that they had developed spontaneously from the broth. -
Spallanzani
Lazzaro Spallanzani boiled broth in sealed flasks for a longer period of time. He then opened several of them and realized that only the opened flasks would become cloudy with microorganisms. experiment explained -
Pasteur
Louis Pasteur boiled broth in S-necked flasks that were open to the air. The broth only became cloudy and full of microorganisms when it got exposed to the dust that collected in the specially shaped neck of the flask. Animation of Redi & Pasteur exp. -
Oparin
Alexander Oparin hypothesized that life began from chemical reactions that we triggered from the energy emitted from the sun, volcanoes and lightning. These chemical compounds then dissolved into the ocean waters and became known as the primordial soup. Oparin theory explained -
Miller & Urey
Stanley Miller and Harold Urey developed a device to mimic the conditions of the early Earth (as Oparin has suggested). They then mixed gases together, heated them and allowed them to cool. They then observed the presence of amino acids in the fluid collected after the experiment. Miller-Urey experiment & its implications -
Fox
Sidney Fox picked up from the Miller-Urey experiment and combined amino acids in an oil bath and heated them up. After several hours he noticed the formation of protein-like materials (called proteinoids) which form long amino acid chains. He then was able to assemble a protocell made of membrane structures and proteinoids. Protocell formation animation -
Margulis
Lynn Margulis proposed the idea that complex cells, such as the Eukaryotic animal & plant cells, could have been formed by Prokaryotic cells coming together and invading larger cells thus forming the organelles we know of today.
