basicmetabolism

basicmetabolism - 9/29/11 Mechanistic Ideas of Life: Basic...

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9/29/11 1 Mechanistic Ideas of Life: Basic Metabolism Phlogiston and Its Demise Why do substances burn? Why do metals rust? Why do animals breath? At the beginning of the 18 th century Georg Ernst Stahl developed and popularized the idea that phlogiston was a colorless, weightless, tasteless, and odorless element released in all of these processes – Once it is released, calx, a basic element, is left behind – Air could only absorb phlogiston if it was dephlogisticated – When air is completely phlogisticated ( fixed ), nothing burned, rusted, or lived Joseph Priestley isolated what we call oxygen but viewed it as fully dephlogisticated air From Lavoisier to Physiological Chemistry The Chemical Revolution – Reversed the elements and compounds of phlogiston chemistry – Oxygen, hydrogen, carbon, nitrogen basic elements Lavoisier and LaPlace: respiration is slow combustion – Measured heat generation by melting of ice in a calorimeter Fermentation an ordinary chemical process (yeast had not yet been observed) – C 6 H 12 O 6 à 2CO 2 + 2C 2 H 5 OH
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9/29/11 2 Jöns Jacob Berzelius (1779-1848) Discovered of the elements calcium, barium, strontium, magnesium, lithium and cerium Established that blood contains iron (1806) Established that muscle tissue contains the same acid as sour milk (lactic acid; 1806-1808) Discovered the chemical formulae for water, ammonia, and various oxides of nitrogen, sulfur and carbon Gave protein its name Discovered pyruvic acid and aconitic acid Introduced the concept and term 'isomerism b Advanced the concept of catalysis (1835), including organic catalysis Digestion of Food Some process of making food soluble – Prout (1824): gastric juice contains hydrochloric acid – Cagniard la Tour and Schwann independently: active enzyme in gastric juice is a catalyst: pepsin • Made active by hydrochloric acid • Ingredient in the original Pepto-bismol, developed to treat l cholera infantum z Other digestive juices, associated with the pancreas, etc., also contain a pepsin-like substance Schwann on the importance of yeast Yeast are living organisms and fermentation only occurs in the presence of yeast Schwann saw himself as a good mechanist – Proposed that fermentation due to the special combination of matter in living cells – But in attributing fermentation to living yeast cells he was viewed by some as making a concession to vitalists
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9/29/11 3 The Chemists ` Response In the 1820s Friedrich Wöhler had
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This note was uploaded on 12/12/2011 for the course PHIL 147 taught by Professor Bechtel,w during the Fall '08 term at UCSD.

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basicmetabolism - 9/29/11 Mechanistic Ideas of Life: Basic...

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