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Bioenergetics: How energy is utilized in living organisms Metabolism Sum of all chemical reactions that occur in body (require energy) (BMR) o Catabolic reactions breakdown of molecules carbs, protein, fat release energy o Anabolic reactions synthesis of molecules (building up) building muscle, storing carbs. or fat Bioenergetics o converting foodstuffs (fats, proteins, carbohydrates) into energy or storing them Cell Structure Cell membrane o protective barrier b/t interior of cell & extra-cellular fluid Nucleus o contains DNA/genes that regulate protein synthesis Cytoplasm o fluid portion of cell o contains organelles (mitochondria) Energy Transformation Forms of Energy o Electrical o Mechanical o Thermal o Chemical 1st Law of Thermodynamics o “energy is neither created nor destroyed, just transferred from one form to another” Energy stored in food, transferred to body & stored when need energy for mechanical work we extract it from carbs, fat, or protein Enzymes Catalysts regulate speed of reaction o lower the “energy of activation” o rate limiting enzyme Interact with specific substrates o lock & key Factors that regulate enzyme activity Temperature (warm up) o Q10 Effect pH (fatigue, buffering agents: sodium bicarbonate) Enzymes Lower Energy of Activation Energy for Exercise Carbohydrates (glucose) o stored as glycogen (liver & muscle) o most rapid form of energy o only fuel used anaerobically o can also be used aerobically o *limited stores; can be depleted Fats (fatty acids & glycerol) o stored as triglycerides (adipose/muscle) o ideal fuel, unlimited, but requires O2 Proteins (amino acids) o not primary energy source o no storage form; found in muscle Usable Energy Source for Body Adenosine triphosphate (ATP) o Energy trapped in phosphate bonds (chemical energy) Carbs, fats, proteins must be catabolyzed into this form before our body can use energy Muscle stores limited amounts (3-5 sec) 3 Mechanisms for Formation of ATP ATP-PC or Phosphogen system: anaerobic Glycolysis: anaerobic (can continue into an aerobic process) Aerobic System: Krebs cycle & electron transport chain 1. “ATP/PC” or “Phosphagen” system Immediate energy source; onset of exercise Approx. 10 sec. of energy System is “anaerobic” & occurs in cytoplasm Replenishment occurs during recovery (3 min): aerobically Short sprint, lift (5 reps), explosive movements 2. Glycolysis Breakdown of “glucose” Occurs in “cytoplasm” of cell “Anaerobic” process Very little energy (ATP) produced, but very quick; “pyruvate” or “lactate” formed depending on availability of O2 2 Stages Energy investment phase; requires ATP Energy generation phase o produces ATP, “NADH” (carrier molecule), & pyruvate or lactate Key Points in Glycolysis Define – breakdown of ONLY glucose to make ATP Energy put in to get going (phosphorylation) Enzymes needed throughout H+ ions pulled off substrate (oxidation) (picked up by NAD) o Good – have energy in them Bad – if can’t use them, they turn pyruvate into lactic acid Lactic acid lowers pH; effect on enzymes??? Small amount of ATP is formed but very quickly Last 2-3 minutes max, anaerobic process (no oxygen present) then need other source of energy 3. Aerobic System (Use of O2 to form of ATP) Occurs in mitochondria Substrates converted to Acetyl CoA only molecule that can enter Krebs cycle 2 Processes: Krebs cycle o completes “oxidation” of substrates & produces NADH to enter… Electron Transport Chain Electron Transport Chain Hydrogens & Electrons are removed from NADH (oxidized) energy in electrons used to concentrate H+ H+ then diffuses back across membrane giving energy to phosphorylate ADP producing ATP H+ then combines with O2 to form water (NO LACTIC ACID) final product of aerobic metabolism: Water, ATP, & CO2 process called oxidative phophorylation all occurs in mitochondria of cell (aerobic process) as long as oxygen is available the process can continue Review of Aerobic Metabolism Occurs in mitochondria of all cells aerobic process Acetyl CoA is formed from substrates; Acetyl CoA enters “Krebs Cycle” & is oxidized H+ & electrons are removed & carried to ….Electron Transport Chain energy in electrons/H+ are used to combine ADP with P to make ATP (oxidative phosphorylation) oxygen combines with H+ to form water & CO2 Without oxygen H+ builds up in ETC pH drops & Krebs cycle & ETC enzymes are inhibited & shut down aerobic metabolism slows NADH can’t drop off more H+ H+ brought to pyruvate (creates lactic acid) Now we can only rely on glycolysis to make more ATP but it eventually shuts down by H+ & lactic acid ATP/PC system is already used up Exercise must stop or slow down b/c there is no way to form ATP Interaction Between Aerobic and Anaerobic ATP Production Energy to perform exercise comes from an interaction b/t aerobic & anaerobic pathways Short-term, high-intensity o > contribution of anaerobic energy systems Long-term, low to moderate-intensity exercise o majority of ATP produced from aerobic sources Always combination of both, which one dominates Where is the Practicality to ATP/PC & Glycolysis? Student: I am thinking about supplementing “creatine”, the bottle says it builds muscle. What do you know about creatine what is it, how does it work, does it work? What are possible limitations? Student: I read that B vitamins (niacin) give us energy, should I supplement them to perform better. What does niacin do? Student: I notice when I lift weights and push myself really hard, I feel a burning sensation in my legs. What is that & is it dangerous, why is it occuring? Student: What causes me to fatigue during exercise (especially high intensity exercise like sprinting)? Is there anything I can do to delay this fatigue? Student: Why do we need oxygen to live, what does it do? What happens, if I cant get enough during exercise? Student: I read that when I weight train for increasing strength, I should weight about 3 minutes between sets, why this amount of time? Student: If I am training for the 400 m (<90 sec), is there any benefit to aerobic training? Student: I was at the “Super Supplement Store” and they were selling “pyruvate” and “Acetyl CoA”. What is that stuff and how does it work? If it works, what would it do? Student: Is basketball an aerobic or anaerobic sport? We will make this much more practical when we talk about developing exercise programs, but we first must understand energy systems Questions on Material The primary function of the krebs cycle is? Explain the role of NAD Where is energy stored in substrates? Describe the 3 Methods for producing ATP. What is the function of ETC? What is contribution of aerobic & anaerobic production at 20, 60 secs, 3 min, 10 min? What is a rate limiting enzyme? What controls these enzymes? Questions on Material, Explain the following Metabolism Anabolic Catabolic Bioenergetics 1st law of thermodynamics Forms of energy Cell membrane, cytoplasm, mitochondria Enzymes, substrates Energy of activation