August 25, 2022CHAPTER 1: CELLS: THE FUNDAMENTAL UNITS OF LIFE NOTESThe Cell Theory-Robert Hooke is the one who coined the term “cell” (first person)-Adapted telescopes by inverting the lenses to see something very close-Cork trees are one of the organisms he used to look at the underlying structure (1665)-Anton van Leeuwenhoek is the one that adapted the microscopes and increased the magnification to about 200 in order to be cells-Hooke used these microscopes to look at cork trees-Leeuwenhoek used them to look at organisms in places like ponds, such as Algae Spirogyra (1674)-*Note these two were in the late 1600’s-In the early 1800s (1838), Schleiden & Schwann proposed 2 tenets of the cell theory:1. All organisms are composed of one or more cells2. Anything that is alive has cells at their bases, because the cell is the structural unit of life-The big question was, where do cells come from in the first place?-The person who put all of the observations of cell theory together and proposed the 3rd tenet was Virchow (1855)-He proposed: Cells can only arise by division from a preexisting cellPasteur Experiment (1864)-He used 2 types of flasks, which differed in the fact that one had a neck that was straight, meaning it was open to the environment, and the other was crooked so that something couldn’t just fall in the flask-The idea was that if cells were just in the environment floating around, they couldn’t get in the flask if it had a crooked neck-He boiled the media (water), which killed any live microorganisms in the media-He then incubated it in the lab for a few days, and he noticed that the flask that was open to the environment had live cells growing in it-This showed two things:1. Cells can’t just spontaneously generate from a bunch of dead cells in the flask that were killed by heat2. There are cells out in the environment -This was strong support for germ theory and a strong argument against spontaneous generationAugust 25, 2022Pasteurization vs. Sterilization-Pasteurization is killing all the live microorganisms through a (“low”) heat treatment-Benefit: Killing all the microorganisms that might make you sick-Drawback: Need to keep milk in a cold place-Killed all the LIVE organisms, but there is still bacteria and microorganisms can grow to create spores-If Pasteur had left the flask with the crooked neck out for another week it would have probably created spores (meaning you would see stuff growing)-Pasteurization maintains the nutritional value-Sterilization is the way to kill all the microorganisms, including spores, through high temperature and pressure-Benefit: It will be safe forever -Drawback: Lacks the nutritional and flavor value Shared Chemistry-All organisms have shared chemistry, such as metabolism, electro-transport chains, transcription, translation-If they share the chemistry, it’s likely they came from common ancestors -When talking about the process in general, it applies to virtually all
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