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Unformatted text preview: BIOL 110: Principles of Biology
Spring 2005 Lecture 12, W 2/16/05
http://www.smccd.net/accounts/staplesn/biol110/ Job for Science/Health majors: Earn some $ on campus as a Lab Prep Assistant in Biology (prefer 1yr + commitment): See Kim Autrey in 18-209, 306-3296. 18306- Quiz #2: In lab this week. Note: You MUST complete each laboratory exercise to get credit for lab attendance. ie: just coming in to take the quiz, etc. doesn't cut it!!! ie: doesn' REVIEW: Ch. 4: How Cells Work Energy (kinetic, Potential; ATP phosphates & electrons) Potential; Chemical Equilibrium Metabolism energetic coupling (ATP as currency) Couple exergonic to endergonic reactions Catabolism (degradation) = exergonic (E releasing & Spontaneous) Anabolism (biosynthesis) = endergonic (E requiring & non-spontaneous) non- TODAY: Ch. 4: How Cells Work Enzymes & regulation (catalysis, substrates, active sites, activation energy) Membrane Transport passive, active, bulk 1 two substrate molecules A. Enzymes: "Induced Fit" Catalyze (speed up) chemical reactions "Biological Catalysts" Catalysts" But are not consumed in reactions! (strain bonds, increase local concentration, orient reactants/substrates correctly....) correctly... substrates contacting active site of enzyme active sight TRANSITION STATE (tightest binding but least stable) end product enzyme unchanged by the reaction Recognize and bind specific substrates (at ACTIVE SITES) Act repeatedly (reused quickly!) Most are proteins; some RNA Activation Energy For a reaction to occur, an energy barrier must be surmounted Enzymes make the energy barrier smaller activation energy without enzyme starting substance activation energy with enzyme energy released by the reaction products direction of reaction 2 Action of Catalase ("Antioxidant")
2H2O2 ----------> 2H2O + O2 (gas) histidine hydrogen peroxide heme group Figur...
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- Spring '09