BIOL 120 1st Edition Lecture 12 Outline of Last Lecture I The Cell Cycle II Chromosomes III Mitosis events IV Checkpoints Outline of Current Lecture I Energy II Metabolism III Cell Energy IV Cellular Respiration Current Lecture I Energy 1 Energy the capacity to do work flows into the biological world from the sun A Kinetic energy of motion B 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 C 2 Laws of Thermodynamics These 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 another B 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 Energy A G Energy available to do work a G H TS b H enthalpy energy in a molecule s chemical bonds stored energy c T absolute temperature d 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 Metabolism 1 Metabolism total of all chemical reactions carried out by an organism A Anabolic reaction making a expend energy to synthesis molecules B Catabolic reaction breaking down a harvest energy by breaking down molecules 2 Biochemical pathways A reactions occur in a sequence B Product of one reaction is the substrate for the next a 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 the first sight because enough material is already present Turns back on once more is needed III Cell Energy 1 Enzymes Biological Catalyst A 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 NADH A ATP adenosine triphosphate is the cellular currency for energy provides the fuel for most cellular activity B NADH is also an energy source a NAD H 2e NADH b reversible reaction 3 Redox Reactions A Reduced an atom or molecule gaining an electron B Oxidized an atom or molecule losing an electron C Oxidation and reduction events are always coupled IV Cellular Respiration 1 Respiration A Glycolysis involves the initial oxidation and partial breakdown of Glucose Glucose 6C to Pyruvic Acid 3C occurs in the cytoplasm B 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 Overview A 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 pyruvate a a series of 10 reactions b Glucose 6C is broken down into two pyruvates 3C c potential energy released is used to form ATP d all of the enzymes needed for glycolysis are found in the cytosol e Energy investment phase 1 Two molecules of ATP are consumed f Energy payoff phase 1 6C is split to form two pyruvates 2 2 molecules of NAD are reduced to NADH 3 4 molecules of ATP are made net gain of 2 ATP B Pyruvate processing pyruvate is oxidized to form acetyl CoA C Citric Acid Cycle acetyl CoA is oxidized to CO2 D 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 ATP A In substrate level phosphorylation ATP is produced by the enzyme catalyzed transfer 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 Processing A 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 CO2 B 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 ATP E Citric acid cycle has a feedback inhibition that prevents over production