Ex Phys Exam I Study Guide 1 What is ATP How does it function How is it formed ATP is the main energy currency in the body Stored in the myofilaments of muscle Energy is released when ATP is converted to ADP ATP ADP Pi ENERGY Only gives 2 4 seconds of energy Everything in the body is controlled via adding or taking off a phosphate o So the body takes chemical energy in the form of ATP and transforms it into mechanical energy in the form of muscle contraction CP creatine phosphate PC used after immediate ATP is used up CP Cr Pi ENERGY Energy from this reaction helps to resynthesize more ATP ATP PC system is immediate energy system 2 Differentiate between aerobic and anaerobic metabolism Because the body cannot easily store ATP reserves only 2 3 seconds these energy systems continually create ATP during exercise by converting nutrients Anaerobic without oxygen o Takes place in the cytosol of the cell o Used for short bursts of exercise maximum exertion o ATP PC system and anaerobic glycolysis o Glucose 2 Pyruvate 2 ATP Lactate Aerobic with oxygen o Takes place in the mitochondria of the cell o Produces more prolonged energy source for exercise but at a slower rate o Relies on O2 as the final electron acceptor so that s why it cannot take place without oxygen o TCA citric acid cycle and ETC respiratory chain o Glucose 2 Pyruvate 2 Acetyl CoA 36 38 ATP 3 Describe glycolysis Glycolysis breakdown of glucose into 2 molecules of pyruvate o Start with blood glucose G6P or glycogen o Initial step addition of 2 phosphates to glucose 2 ATP o Result 6 carbon sugar diphosphate and 2 low energy ADP o Next it is split into two 3 carbon molecules which are then converted through a series of steps to pyruvate 2 o During these reactions electrons are transferred to the coenzyme NAD to form NADH and ATP is formed NET YEILD 2 ATP and 2 NADH per molecule of glucose o If glycogen is used rather than free glucose circulating in blood then one more ATP will be formed for a total of 3 ATP Under aerobic conditions the pyruvate is further oxidized to yield more ATP o Pyruvate oxidizes to Acetyl CoA which then acts as a metabolic intermediate as it can enter the TCA cycle providing energy for the cell or it can be transformed into fatty acids instead it is converted into lactic acid which Under anaerobic conditions accumulates in the muscles o Usually due to the ETC not being able to process all of the H from NADH when oxygen supply is low o These unprocessed H can attach to pyruvate and from lactate via lactate Regulation o Also called the lactic acid system because lactic acid is the end product by PFK levels of fructose 1 6 biphosphate oxygen and ATP levels o High blood glucose levels after a meal glycolysis is stimulated by dehydrogenase insulin o Low blood glucose levels during fasting or exercise gluconeogenesis is stimulated by glucagon o Glycolysis is crucial for exercise lasting up to 90 seconds 4 Describe the Krebs cycle and ETS Require oxygen If energy is not required right away as in endurance exercise the pyruvates will enter the cell s mitochondria rather than forming lactate TCA cycle aka Krebs involves the conversion of acetyl CoA from pyruvate into several intermediates that serve to produce ATP o Pyruvate Acetyl CoA achieved by removing a CO2 molecule and then removing an e to reduce NAD to NADH An enzyme called coenzyme A is combined with the remaining acetyl to make acetyl CoA which is then fed into the cycle o Acetyl CoA creates 6 carbon citric acid and the cycle ends with a 4 carbon oxaloacetate which then combines with acetyl CoA again to repeat the cycle over and over o NET YIELD one turn 3 NADH 1 FADH2 1 ATP and releases 2 CO2 o Remember we have 2 molecules entering the cycle so its doubled ETC electron transport chain happens in the mitochondria of the cell o NADH and FADH2 molecules give up their e and H atoms to create a proton gradient of stored energy NADH 3 ATP per molecule FADH 2 ATP per molecule o Happens at the same time the TCA cycle is occurring o 12 H2O are produced at the end of ETC TOTAL BREAKDOWN OF GLUCOSE 36 ATP Breakdown of Fats Fat is a much larger source of fuel compared to glucose o 30 more energy ATP then carbs o Fats 9 calories while CHO only 4 The body prefers to use fat but it is not as readily available so its only used for sub maximal exercises Oxygen MUST be available for fat to be used as fuel o Breakdown of triglyceride to 3 free fatty acids o Free fatty acids are transported in blood to muscle mitochondria where they are prepared for catabolism energy activation Chylomicrons transport FA into mitochondria o Breakdown of FA to Acetyl CoA through beta oxidation NADH and FADH2 are produced o Coupled oxidation in TCA cycle and ETC Lactic acid inhibits fatty acid mobilization Beta Oxidation Fatty acid oxidation Involves successive splitting of 2 carbon acyl fragments from the long chain FA Happens in the mitochondria Acyl fragments join with coenzyme A to form Acetyl CoA Continues repeats until the entire fatty acid molecule degrades into Acetyl CoA o Which then directly enters the Krebs cycle o H ions released oxidize through the ETC Note fatty acid breakdown directly relates to oxygen consumption o O2 must join with hydrogen for B oxidation to proceed hydrolysis NET YIELD with TCA and ETC 441 ATP from one triglyceride o Each triglyceride molecule contains 3 fatty acids o One fatty acid total 147 ATP so 3 x 147 441 5 Compare and contrast the three energy systems ATP CPr Pathway immediate supplies 10 seconds worth of energy o Most powerful system o First uses up any ATP stored in the muscle o Then uses creatine phosphate CP to resynthesize ATP until CP runs out ADP CP ATP C ADP triggers the release of CK which catalyzes this reaction o After ATP and CP are used up the body will move on to either aerobic or anaerobic metabolism Anaerobic Metabolism short term Glycolysis lactic acid system creates ATP exclusively from carbohydrates with lactic acid being a by product o 2nd most powerful system o Provides energy by the partial breakdown of glucose without O2 o For short high intensity bursts of activity lasting no more than a several minutes o Lactic acid builds up causing muscle burning and fatigue Aerobic Metabolism long term fuels most of energy needed for long duration activity by using oxygen to convert nutrients carbohydrates fats and protein to ATP o Slower because it relies on the circulatory system to transport O2 to the o Primarily used during
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