BIOL 1103 LECTURE NOTES - Historical Figures in Scienceo Aristotle is very first person to write about spontaneous generation Believed in abiogenesis “life from non-life”o Theophrastus Paracelsus was Swiss medical philosophero Van Helmont was a physician and alchemist Experimented with how to produce (draw) mice with a dirty shirt in a vesselo Fransisco Redi was first scientist to really emphasize biogenesis (as opposed to abiogenesis) life comes from previous life To determine biogenesis, experimented with decaying fish Put decaying fish in vessel, uncovered, and flies appeared (life from life); put decaying fish in vessel and covered with clay and no flies appeared Believers in abiogenesis believed that the clay was trapping the ‘soul’ of the fly out and thereby not allowing it to reproduce Redi put sheath cloth over vessel with decaying fish to let the flies’ ‘soul’ in still no flies appeared This experiment is considered to have debunked abiogenesis theoryo Van Leeuwenhoek is the inventor of the microscope First person to find: bacteria, free-living and parasitic microscopic protists, sperm cells, blood cells Leeuwenhoek, contradictory to Redi’s experiment, thought that these microbes arised from spontaneous generationo 1860: French Academy of Science offered reward to anyone who could prove one way or another about spontaneous generationo T. Schwann experimented to show biogenesis of microorganisms in 1837o Louis Pasteur experimented with spontaneous generation Used a swan-necked flask experiment (diagram in book) Won reward from French academy and officially disproved abiogenesis- Cell Theoryo Cell theory all life is made of cells and all cells come from previously existing cellso Atoms the smallest particle of any element o Subatomic particles protons, neutrons, electronso Atoms has never been seeno Atomic number number of protons; this number is always equal to the number of electronso Atomic mass mass of protons, neutrons, and electrons (though electrons havepractically no mass)o Electrons occur in pairs in stable atomso Molecule combo of atoms, such as: water, methane, glucose- Bondso Bond connection of one atom to another Covalent (strongest), ionic, and hydrogen bondso Louis Dot model created to show covalent bonds by using dots instead of usual dasheso Valence [electrons] how many pairs of electrons are shared (covalence) Hydrogen has 1 valence Oxygen has 2 valences Nitrogen has 3 valences Carbon has 4 valenceso Ionic bond results from gain or loss of an electron Ion atom that’s gained or lost an electron and now has a chargeo Covalent bonds share electron pairsH atomH atomCovalent bond, shared
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