Theory of Biogenesis

Theory of Biogenesis - broth in the flasks did not decay or...

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Theory of Biogenesis living cells can arise only from preexisting living cells Rudolf Virchow, 1858 1861, Pasteur demonstrated that microbes are present in the air and can contaminate sterile solutions, but the air itself does not create microbes Pasteur filled several short-necked flasks with beef broth and boiled the broth. Some flasks were left open for several days and were found to be contaminated Other flasks were sealed after boiling and were free of microbes (remember before the flasks were sealed before boiling) Results allow for reasoning that microbes in the air contaminated the flasks to further prove that air-borne microbes do not spontaneously generate, Pasteur performed a second experiment Pasteur placed broth in a long-necked flask and bent the neck of the flask into a "s" curve he then boiled the broth and allowed it to cool
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Unformatted text preview: broth in the flasks did not decay or become contaminated for long periods air was allowed to freely move in or out of the flask but air-borne microbe were trapped in the curve of the neck some of the flasks still show no contamination even now over 140 years later Later experiments of Pasteur’s proved that microbes can be present in nonliving matter, solids, liquids, in air Also demonstrated that microbes can be destroyed by heat And methods can be devised to block the access of airborne microbe to nutrient environments These discoveries form the basis of aseptic techniques, techniques that prevent contaminations by unwanted microbes standard practice in laboratory and medical procedures FIRST AND MOST IMPORTANT THING YOU WILL LEARN IN LAB...
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This note was uploaded on 01/23/2012 for the course MCB MCB2010 taught by Professor Smith during the Fall '09 term at Broward College.

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