Slide 1 Slide 2 Slide 3 Slide 5 Slide 6 Slide 7 Note if there are no notes for a slide it just means the book didn t have any extra information that wasn t on the slide or that the slide if pretty self explanatory or Lecture 10 Notes How the cell converts external energy sources such as chemical nutrients or sunlight into a intracellular chemical energy carrier Adenosine Triphosphate ATP ATP is found in all types of organisms it is generated from ADP and inorganic phosphate HPO4 2 or Pi Cells use the energy released during hydrolysis http faculty ccbcmd edu biotutorials energy adpan html of the high energy phosphoanhydride bond in ATP to power many otherwise energetically unfavorable processes Energy to drive ATP synthesis from ADP is produced primarily by two processes Aerobic Oxidation occurring in the Mitochondria in all eukaryotic cells and photosynthesis which occurs in chloroplasts on in leaf cells of plants and certain single celled organisms Two additional processes glycolysis and the citric acid cycle are also important sources of ATP Slide 4 energy stored in the covalent C bonds will be utilized by the cell most of energy is stored in carbohydrates the cell ef ciently degrades the 6 carbon molecule the covalent C bond will undergo oxidative phosphorylation to produce CO2 Substrate level phosphorylation glycolysis occurs in the cytoplasm Substrate level phosphorylation is a type of metabolism that results in the formation and creation of adenosine triphosphate ATP or guanosine triphosphate GTP by the direct transfer and donation of a phosphate PO3 group to adenosine diphosphate ADP or guanosine diphosphate GDP from a phosphorylated reactive intermediate Oxidative Phosphorylation is a metabolic pathway that uses energy released by the oxidation of nutrients to produce ATP During oxidative phosphorylation electrons are transferred from electron donors to electron acceptors such as oxygen in redox reactions These redox reactions release energy which is used to form ATP In eukaryotes these redox reactions are carried out by a series of protein complexes within mitochondria A proton electrochemical gradient is generated across a membrane driven by energy released as electrons travel through an electron transport chain The energy store in this gradient called the proton motive force is used directly to power the synthesis of ATP and other energy requiring processes Slide 8 stage 1 glycolysis in the cytoplasm Slide 9 we divide them into 4 stages this all just happens continuously we just break it up into stages to make it clearer this slide set focuses on Stage 1 plants have chloroplasts that can synthesize carbohydrates by harvesting sunlight energy that x CO2 into carbs like glucose 6 C molecules kind of like reverse of what happens in mitochondria harvest CO2 and x it to carbs Top half of Diagram In aerobic oxidation fuel molecules primarily sugars and fatty acids undergo preliminary processing in the cytosol breakdown of glucose to pyruvate stage 1 and are then transferred into mitochondria where they are converted by oxidation with O2 to CO2 and water stages 2 3 and ATP is generated stage 4 Glucose Oxidation Stage I Conversion in the cytosol of one 6 Carbon glucose molecules to two 3 Carbon pyruvate molecules glycolysis Stage II Pyruvate oxidation to CO2 in the mitochondrion via 2 Carbon acetyl CoA intermediate citric acid cycle Stage III Electron transport to generate a proton motive force Stage IV ATP synthesis in the mitochondrion oxidative phosphorylation uni direction irreversible can t go back to original molecule KINASE alternatively known as a phosphotransferase is a type of enzyme that transfers phosphate groups from high energy donor molecules such as ATP 2 to speci c substrates 3 steps are irreversible and the others are reversible don t have to know every single step and memorize steps 1 3 10 are irreversible involve kinases and are critical know these Glycolysis Does not require oxygen called anaerobic glucose catabolism biological breakdown of complex to simpler substances During glycolysis cytosolic enzymes convert glucose to pyruvate A set of 10 water soluble cytosolic enzymes catalyze the reactions constituting the glycolytic pathway think glyco sweet lysis split in which one molecule of glucose is split into two molecules of pyruvate In addition to producing 2 pyruvates and intermediates these enzymatic reactions generate 4 ATP molecules by phosphorylation of 4 ADP s steps 7 10 a process called substrate level phosphorylation to distinguish it from the oxidative phosphorylation that generates ATP in the 3rd stage of aerobic oxidation Figure Glucose is degraded to pyruvate 2 reactions consume ATP forming ADP and phosphorylated sugars red two generate ATP from ADP by substrate level phosphorylation green and one yields NADH by reduction of NAD yellow Note that all the intermediates between glucose and pyruvate are phosphorylated compounds Reactions 1 3 and 10 with single arrows are essentially irreversible large negative delta G value under ordinary cell conditions Slide 10 Slide 11 Slide 12 This is the balanced chemical equation for the conversion of glucose to pyruvate produces net gain of 2 atp molecules most of the energy is stored in the electrons Glycolysis of 1 molecule of glucose gives a net gain of 2 atp molecules energy production by glycolysis is essentially a minimum cell cannot harvest in glycolysis in the cytosol after oxidative phosphorylation you have 30 atp molecules Electron carriers NADH carriers two electrons Remember LEO goes GER Lose Electrons Oxidized Gain Electrons Reduced 2NADH are produced after glycolysis this is a bigger molecule and is less easily transported across the membrane needs carrier proteins will discuss later FADH can be utilized as the e carrier has reducing power can carry e s E stored in the C covalent bond after glycolysis produces 2 molecules of atp most energy produced by glycolysis is carried in the e s which are transported to the inner membrane of the mitochondria Proton Motive Force Transmembrane concentration and electrical voltage gradients collectively called the proton motive force are generated during aerobic oxidation and photosynthesis in eukaryotes and prokaryotes bacteria High energy electrons generated by light absorption by pigments chlorophyll or held in the reduced form of electron carriers NADH FADH2 made during the catabolism breakdown of sugars and lipids pass down an electron transport