Download Bioenergetics: How energy is utilized in living organisms

Bioenergetics: How energy is utilized in living organisms
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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
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Energy for Exercise
Carbohydrates (glucose)
o stored as glycogen (liver & muscle)
o most rapid form of energy
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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
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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)
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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
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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
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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
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2 Stages
Energy investment phase; requires ATP
Energy generation phase
o produces ATP, “NADH” (carrier molecule), & pyruvate or lactate
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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
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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
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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
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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
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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
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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?
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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