Metabolism Flashcards
ATP-PCr system (characteristics, how it responds, how it adapts to exercise, what type of activity would this activate)
Characteristics:
- Simplest of energy systems
- Anaerobic substrate-level metabolism
- Reassembles ATP because ATP stores are limited
How it responds:
- Replenishes ATP stores during rest (ATP recycling) using energy from PCr’s breakdown from creatine kinase
- CK controls rate of ATP production
- When ATP levels are low, CK activity is high and vice versa
How it adapts to exercise:
- Recycles ATP during exercise until used up (~3-15s max exercise)
Activities: Short sprints up the stairs
Glycolytic system (characteristics, how it responds, how it adapts to exercise, what type of activity would this activate, pros and cons)
Characteristics:
- Anaerobic
- Breakdown of glucose via glycolysis
- More complex than ATP-PCr system
How it responds:
- Aerobic: relatively slow process resulting in substantial ATP formation
- Anaerobic: rapid but limited ATP production that produces lactate as the end product
How it adapts to exercise:
- When ATP is low, PFK is high and vice versa
- ~2 min max exercise
Activity: 800m run
Pros:
- Fast; readily available; allows muscle to contract when low O2; allows short, high-intensity exercises
Cons:
- Inefficient; low ATP yield; lack of O2 converts pyruvate to lactic acid; lactic acid impairs glycolysis, muscle contraction
Oxidative system (characteristics, how it adapts to exercise, what type of activity would this activate)
Characteristics:
- Aerobic
- Krebs cycle
- Steady supply for hours
- Most complex of three systems
- Occurs in mitochondria, not cytoplasm
- 32-33 ATP/1 glucose
How it adapts to exercise:
- When ATP is low, IDH activity is high and vice versa
Activity: Running a marathon
ATP basics
- Stored in small amounts until needed
- Body must constantly synthesize new ATP via ATP-PCr system, Glycolytic system and Oxidative system
Phosphocreatine (PCr)
- Provides energy for ATP resynthesis
- Releases a large amount of energy when the bond splits between the creatine and phosphate molecules
- Hydrolysis of PCr begins at the onset of intense exercise
- Cells store PCr in considerably larger quantities than ATP
Carbs (role in bioenergetics, basic characteristics, how it’s metabolized and how its involved in the regeneration of ATP)
- Short, high-intensity exercises
- Converted to glucose, excess stored in liver and muscles
- 4.1 kcal/g; ~2,500 kcal stored in body
- Primary ATP substrate for muscles and brain
Fats (role in bioenergetics, basic characteristics, how it’s metabolized and how its involved in the regeneration of ATP)
- Used for prolonged, less intense exercise
- Efficient substrate, efficient storage
- 9.4 kcal/g
- +70,000 kcal stored in body
- High net ATP yield but slow ATP production
- Broken down into FFAs and glycerol
Proteins (role in bioenergetics, basic characteristics, how it’s metabolized and how its involved in the regeneration of ATP)
- Used during starvation
- 4.1 kcal/g
- Converted into glucose via gluconeogenesis
- Can also convert into FFAs via lipogenesis for energy storage
Glycolysis (basics, what’s happening, net ATP production, rate limiting enzymes)
Basics:
- Carbohydrate breakdown
What’s happening:
- Uses glucose or glycogen as its substrate, converting it to glucose-6-phospate
- Costs 1 ATP for glucose, 0 ATP for glycogen
- Pathway starts with glucose-6-phosphate, ends with pyruvate
Net ATP production:
2 ATP
2 NADH
2 Pyruvate
Rate-limiting enzyme:
- PFK (phosphofructokinase)
Krebs cycle (basics, what’s happening, net ATP production, rate limiting enzymes)
Basics:
- Oxidation of carbohydrates
What’s happening:
- 1 molecule of glucose yields: 2 acetyl-CoA; 2 complete Krebs cycles; double ATP yield
- Also produces NADH, FADH2 and H+
- Too many H+ in the cell = too acidic so moved to electron transport chain
Net ATP:
6 NADH
2 ATP
2 FADH2
Rate limiting enzyme:
- Isocitrate Dehydrogenase
Electron transport chain (what’s happening, net ATP production, rate limiting enzymes, key steps)
What’s happening:
- H+ electrons carried to chain via NADH, FADH molecules
- H+ electrons travel down the chain
- H+ combines with O2
- Electrons and O2 form ATP
Net ATP:
- 2.5 ATP per NADH
- 1.5 ATP per FADH
Beta oxidation of Fat (basics, what’s happening, net production, rate limiting enzymes, key steps)
Basics:
- Process of converting FFAs to acetyl-CoA before entering Krebs cycle
- Requires 2 ATP up front
- Number of steps depends on number of carbons on FFA
Net:
- 16-carbon FFA yields 8 acetyl-CoA
- 1 glucose yields 2 acetyl-CoA
- Yields 3-4 times more ATP than glucose
What are the end fates of lactate?
- Synthesized to glucose via gluconeogenesis in muscle
- Or synthesized to glucose via Cori Cycle (gluconeogensis in liver) in the liver to be utilized in skeletal muscle
- Can be taken up by the mitochondria and oxidized
- Supplies fuel for use in other cells
