W1-L3: Energy Metabolism Flashcards
What is Phosphocreatine? (PcR)
- A high-energy phosphate compound
- Cells store approximately 4-6x more PCr than ATP
- Free energy releases when the bond cleaves between PCr’s creatine and phosphate molecule
PCR Enzymes
PCr and ATP during SPRINT exercise
explain
Can physical training increase the muscles’ quantity of high-energy phosphates?
yes do interval of maximal movement training to increase storage
Cellular oxidation: Electron Transport
slide 35
3 ATP for every NADH + H+…but really 2.5.. Why?
2 ATP for every FADH2 … but really 1.5… Why?
https://www.youtube.com/watch?v=zJNx1DDqIVo
uses ATP
What are the 3 requirements for an uninterrupted electron transport chain?
- Tissue availability of the reducing agent NADH or FADH2
- Presence of the oxidizing agent oxygen in the tissues
- Sufficient concentration of enzymes and mitochondria to ensure that energy transfer reactions proceed at their appropriate rate
What are the 3 Stages of Energy release form Macronutrients?
Stage 1: digestion, absorption and assimilation of large food macromolecules into smaller subunits for use in cellular metabolism
Stage 2: degrade amino acid, glucose, fatty acid and glycerol units within the cytosol into acetyl-coenzyme A, with limited ATP and NADH production
Stage 3: within the mitochondrion, acetyl-coenzyme A degrades to CO2 and H2O with considerable ATP production
What is Aerobic or slow Glycolysis?
- Slow process
- Substantial ATP formation
- pyruvate become the end product. Will go through other processes to further breakdown in the citric acid cycle and electron transport production of ATP
What is Anaerobic or rapid Glycolysis?
- Rapid process
- Limited ATP production
- Lactate is formed from pyruvate and is the end produc
Energy Release from Carbohydrate
1:1 Ratio
What is Rapid Glycolysis, where does it take place?
- Occurs outside of the mitochondria
- Important for maximum effort physical activity for up to about 90s
What is Glycogenesis?
glycogen synthesis
What is Glycogenolysis?
glycogen breakdown
- the glycogen reacts with a phosphate and become G6P
- When this occurs, we get a net gain of 3 ATP instead of 2 ATP
What is the starting substrate of Glycolosis?
What is the Net Gain of ATP?
What if the starting Substrate is Glycogen?
Glucose
The net gain of ATP in glycolysis is 2 ATP molecules per glucose molecule.
we get a net gain of 3 ATP instead of 2 ATP
Glucose to G6P uses 1 ATP (not glycogen)
make 2 ATP
use 2 ATP
make 2 ATP
Net Gain of 2
research more on when each ATP is used
What Three factors regulate glycolysis?
Need to know specific enzymes (rate-limiting Enzymes)
- Concentration of the four key glycolytic enzymes: hexokinase, phosphorylase, phosphofructokinase and pyruvate kinase
- Levels of the substrate fructose 1-6-diphosphate
- Oxygen, which in abundance inhibits glycolysis
What is Lactate?
“steady rate” exists when hydrogen oxidizes at about
the same rate it becomes available
Lactate
What is the Cori Cycle?
Cori cycle removes lactate released from active muscles and uses it to replenish glycogen reserves depleted from intense physical activity
What is Lactate shuttling?
Lactate shuttling is a process whereby lactate produced in one muscle fiber will circulate to another, convert to pyruvate then to acetyl CoA and enter the citric acid cycle
What happens if energy demand exceeds O2 supply or its rate of use?
need to make lactate to replinish NAD+
check that
The Citric Acid Cycle (also Krebs Cycle)
A more in depth look at the citric acid cycle
NET ATP GAIN
Anaerobic Versus Aerobic Glycolysis
Anaerobic Versus Aerobic Glycolysis
- Two forms of carbohydrate breakdown:
- Anaerobic (rapid) glycolysis results in pyruvate-to- lactate formation with the release of about 5% of energy within the original glucose molecule -Rapid, but less ATP
- Aerobic (slow) glycolysis results in pyruvate-to- acetyl-CoA-to-citric acid cycle and electron transport of the remaining energy within the original glucose molecule - Slower, but more ATP (Efficient)
Net ATP Gain from glycolosis and Krebs
Energy Release from Fat
Fuel reserves from fat come from 2 main sources:
1. 60,000-100,000 kcal form triacylglycerol in fat cells
2. 3000 kcal from intramuscular triacylglycerol
Perspective: Carbohydrates energy reserves generally amount to less than 2000 kcal
Fat Catabolism comes from what?
- Triacylglycerols stored directly within the muscle fiber in close proximity to the mitochondria
- Circulating Triacylglycerols in lipoprotein complexes that become hydrolyzed on the surface of a tissue’s capillary endothelium
- Circulating free fatty acids mobilized from Triacylglycerols in adipose tissue
What is Beta oxidation?
What does it produce?
removal of 2- carbon units by oxidation at the fatty acyl-CoA molecule
Each round of B-oxidation produces one mole of NADH, one mole of FADH2 and one mole of acetyl-CoA
What is the Total energy transfer from fat catabolism?
- For each 18-carbon fatty acid molecule, 147 ATP are formed
during B-oxidation and citric acid cycle metabolism X3 = 441 ATP - 19 ATP are formed during glycerol breakdown
