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EX PHYS TEST I I. Bioenergetics 1. What is ATP? How does it function? How is ATP formed? ATP is an energy-rich compound that stores energy which powers all of the cell’s energy requiring processes. Potential energy is conserved within the bonds of ATP through food sources. This potential energy is then extracted and transferred into chemical energy to power biological work. Formation: ATP is formed from a triphosphate group, a ribose, and the nucleotide Adenine (ribose + adenine=adenosine). The bonds that link to the outermost phosphates represent high-energy bonds because they release considerable amounts of energy during hydrolysis. Therefore, the hydrolysis of a phosphate form ATP serves as its energy generating mechanism. ATP uses this mechanism to donate phosphates in creating new cellular material.2. Differentiate between aerobic and anaerobic metabolism. a. Aerobic: Metabolism that occurs in the presence of oxygen. These processes occur in the mitochondria only. TCA (citric acid cycle) and ETC (respiratory chain/electron transport chain) occur through exclusively aerobic conditions (oxygen supply is mandatory). Aerobic metabolism produces a more prolonged energy source for exercises including marathons, swimming, walking, etc. Energy is produced at a slower rate. These activities rely on oxygen as a final electron acceptor so without oxygen, exercise is unable to be sustained. i. Glucose 2 Pyruvate  2 Acetyl CoA 36 ATP b. Anaerobic: Metabolism that occurs in the absence of oxygen. These processes cannot occur in the mitochondria because oxygen isn’t available, a requirement for this organelle. Instead, these processes occur in the cytosol. These processes include the regulation of phosphocreatine, glucose/glycogen, glycerol, and some deaminated amino acids. This type of metabolism occurs when an individual is participating in situations where oxygen isn’t readily available (asthma, maximum exercise). A large amount of energy is produced but it is quick to fatigue. Examples would include sprinting and power training. i. Glycose  2 Pyruvate (2 ATP)  Lactate 3. Describe glycolysis. Glycolysis includes the breakdown of glucose to two molecules of pyruvate. Glycolysis is stimulated when there are high blood glucose levels and the body acts to remove glucose from the blood by breaking it down into pyruvate which can lead to different pathways. Glucose is brought into the cell through GLUT-4. Glut- 4 is located on the cell membrane, stimulated by physical activity and insulin, and it allows glucose entry into the sarcoplasm for ATP synthesis. (*** TEST QUESTION) During aerobic conditions: pyruvate oxidizes to acetyl-CoA. Acetyl-coA then acts as a metabolic intermediate as it can enter the TCA cycle providing energy for the cell or be transformed into fatty acids (FA synthesis). During anaerobic conditions: pyruvate is instead reduced to lactic acid which accumulates in the muscles.Regulation: Glycolysis occurs in the cytoplasm and is regulated by PFK, levels of fructose-1,6-bisphosphate, oxygen, and ATP levels. When there are high blood glucose levels (such as after a meal) glycolysis is stimulated by insulin. When there are low blood glucose levels (during fasting or exercise) gluconeogenesis is stimulated by glucagon. Glycolysis is crucial for exercise lasting up to 90 seconds. (*** test question) a. Know net ATP yield, depending on substrate used and know what other energetic molecules are formed. *** Net reaction: Glucose + 2NAD+ + 2ADP + 2Pi  2 Pyruvate + 2ATP + 2NADH + 2H+ + 2H22 ATP produced Glycogen Glucose Pyruvate (extra ATP produced with breakdown from glycogen)3 ATP produced b. How is lactate formed from glycolysis? What are the conditions under which it is formed? Lactate is formed from pyruvate (final product in glycolysis) during anaerobic conditions. Lactate builds up during high intensity resistance training or sprinting activities when the body doesn’t have an adequate oxygen supply for the given activity. This is usually due to the fact that the ETC cannot process all of the hydrogens from NADH when oxygen supply is low. These unprocessed hydrogens can then attach to pyruvate and form lactate via lactate dehydrogenase. NADH H+ is oxidized to NAD+ which serves to continue glycolysis, hence why lactate production is so important during activities that rely primarily on carbohydrate metabolism. 4. Describe the Krebs Cycle (TCA cycle). The TCA cycle involves the metabolism of acetyl-CoA from pyruvate into several intermediates that serve to produce ATP. Acetyl coA is broken down to carbon dioxide (6 molecules) and hydrogen atoms (20 ) within the mitochondria. ATP is produced when hydrogen atoms oxidize to water during oxidative phosphorylation in the ETC cycle. The primary function is to generate electrons for passage (via NADH H+ and FADH2) in the respiratory chain to NAD+ and FAD. With adequate oxygen supply, NAD+ and FAD regenerate. a. Know what happens to pyruvate before entering the Krebs cycle. Pyruvate is first oxidized to acetyl-CoA by pyruvate dehydrogenase complex. THIS REACTION IS IRREVERSIBLE. Acetyl-CoA, considered the universal intermediate between carbohydrates, lipids, and proteins, can then enter the Krebs cycle and produce energy for demanding cells. This process requires oxygen and deals with mostly lipolysis and aerobic glycolysis. b. Know what important high energy molecules are formed (e.g. FADH2, NADH+ H+, ATP). For each the complete metabolism of one molecule of acetyl-CoA: o3 NADH H+: each NADH releases 3 ATP (3 X 3 = 9 ATP) o1 FADH2: each FADH2 releases 2 ATP (1 X 2 = 2 ATP) o1 ATP are produced via substrate phosphorylation 1. TOTAL ATP= 12For the complete metabolism of glucose: This 10 ATP is doubled because one molecule of glucose yields two molecules of acetyl-CoA so total glucose metabolism from the TCA cycle would be 24 ATP. 5. Know what the role of NADH + H+ and FADH2 in the ETC and the differences in energy yield. The electron transport cycle utilizes NADH H+ and FADH2 as electron carriers which enter the respiratory chain at complexes I and II. Each molecule of NAD+ (Niacin-containing coenzyme) gains a proton and two electrons, reducing to NADH + H+ which produces 3 ATP (P: O ratio= 3). Each molecule of FAD+ (riboflavin-containing coenzyme) gains two hydrogens and two electrons, reducing to FADH2 which produces 2 ATP (P: O ratio=2). a. Know the general mechanism by which energy is produced in


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FSU PET 3380C - PHYS TEST I

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