BIOL 120 1st Edition Lecture 12Outline of Last LectureI. The Cell Cycle II. ChromosomesIII. Mitosis events IV. Checkpoints Outline of Current LectureI. EnergyII. MetabolismIII. Cell EnergyIV. Cellular Respiration Current LectureI. Energy1. Energy: the capacity to do work (flows into the biological world from the sun)A. Kinetic: energy of motionB. Potential: stored energy (found in chemical bonds)C. Comes in many forms: mechanical, heat, sound, electrical current, light or radioactivity a). heat is the best for measuring 1 calorie= heat required to raise 1 gram of water 1 degree C2. Laws of ThermodynamicsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.A. First law energy cannot be created or destroyed, it can only change from one form to anotherB. Second law Entropy (disorder) is continuously increasing (energy transformations occurring spontaneously to get matter from less stable to more stable and vice versa)3. Free EnergyA. G = Energy available to do worka). G = H – TSb). H = enthalpy, energy in a molecule’s chemical bonds (stored energy)c). T = absolute temperatured). S = entropy, unavailable energy (cannot be used by the system) B. Positive ∆G Endergonic (add energy to system) Products have more free energy than reactants C. Negative ∆G Exergonic (release energy from chemical reaction) Products have less free energy than reactants II. Metabolism1. Metabolism: total of all chemical reactions carried out by an organismA. Anabolic reaction (making)a). expend energy to synthesis molecules B. Catabolic reaction (breaking down)a). harvest energy by breaking down molecules 2. Biochemical pathwaysA. reactions occur in a sequence B. Product of one reaction is the substrate for the nexta). i.e. A B C D …..(substrate (A) product (B)) (each step catalyzed by enzymes)3. Feedback inhibition A. Shutting down enzyme activity by binding the end product of a pathway to thefirst sight because enough material is already present Turns back on once more is neededIII. Cell Energy1. Enzymes: Biological CatalystA. Most enzymes are proteins and their shape helps stabilize a temporary association between substrates B. Enzymes are not consumed or changed in the reaction 2. ATP and NAD / NADHA. ATP: (adenosine triphosphate) is the cellular currency for energy: provides the fuel for most cellular activityB. NADH: is also an energy sourcea). NAD + H + 2e = NADH b). reversible reaction 3. Redox ReactionsA. Reduced= an atom or molecule gaining an electronB. Oxidized = an atom or molecule losing an electron C. Oxidation and reduction events are always coupled IV. Cellular Respiration1. RespirationA. Glycolysis: involves the initial oxidation and partial breakdown of Glucose (Glucose 6C to Pyruvic Acid 3C) occurs in the cytoplasmB. Citric Acid Cycle: is the further removal of the electrons from the remnants of Glucose (Pyruvate) occurs in the matrix of the mitochondria C. Electron transport chain: where the energy of the electrons from oxidation reactions is used to make ATP occurs in the cristae of the mitochondria 2. Photosynthesis: converts light energy to chemical energy and is the reverse of respiration (turning carbon dioxide and water into sugar)3. Oxidation of Glucose A. carbon atoms of glucose become carbon dioxide and oxygen atoms become water B. In cells glucose is oxidized through a long series of controlled redox reactions resulting in a change of free energy being used to make ATP from ADP IV. Cellular Respiration 1. OverviewA. organisms use glucose to build carbs, fats, and other compounds cells then recover glucose by breaking down molecules a). Glucose is used to make ATP through cellular respiration or fermentation B. Cellular respiration makes ATP from molecules with high potential energy (glucose) 2. Steps A. Glycolysis breaking down glucose into pyruvatea). a series of 10 reactionsb). Glucose (6C) is broken down into two pyruvates (3C)c). potential energy released is used to form ATPd). all of the enzymes needed for glycolysis are found in the cytosole). Energy investment phase1). Two molecules of ATP are consumed f). Energy payoff phase1). 6C is split to form two pyruvates2). 2 molecules of NAD are reduced to NADH3). 4 molecules of ATP are made (net gain of 2 ATP)B. Pyruvate processing pyruvate is oxidized to form acetyl CoAC. Citric Acid Cycle acetyl CoA is oxidized to CO2D. Electron transport and chemiosmosis compounds that were reduced in steps 1-3 are oxidized in reactions leading to ATP production a). B, C, D take place in the mitochondria 3. Methods of producing ATPA. In substrate level phosphorylation ATP is produced by the enzyme-catalyzedtransfer of a phosphate group (how ATP is produced in glycolysis and the citric acid)B. In electron transport chain proton gradient provides energy for ATP production membrane protein ATP synthase uses this energy to turn ADP to ATP (called oxidative phosphorylation) 4. Pyruvate ProcessingA. second step in glucose oxidation it is catalyzed by pyruvate dehydrogenase in the mitochondrial matrix B. In the presence of O2 pyruvate produces acetyl CoA and NADH and CO2 5. Citric Acid Cycle A. during this step acetyl CoA is oxidized to 2 molecules of CO2B. some potential energy released is used to: reduce NAD to NAFH, reduce FAD to FADH2, Phosphorylate GDP to GTP (later become ATP)C. This cycle completes glucose oxidation D. for one glucose the citric acid cycle has to run twice producing 6 NADH, 2 FADH, and 2 ATPE. Citric acid cycle has a feedback inhibition that prevents over
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