Muscle Energetics Flashcards
How much work does a muscle produce per mole of ATP?
24kJ
What is the resting EC? Does this favour ATP hydrolysis or resynthesis?
Around 0.95. ATP hydrolysis more favourable
How does the concentration of ATP, ADP, and AMP of fast muscle compare to that of slow muscle at rest?
ATP higher in fast muscle
ADP and AMP are about the same (as is EC)
What happens to the concentration of ATP, PCr, and lactate as a result of exercise intensity?
ATP doesn’t change
PCr declines slightly
Lactate greatly increases
What is phosphocreatine?
It serves as a rapidly mobilisable reserve of high energy phosphates.
Can anaerobically donate a phosphate group to ADP to form ATP in first 2-7s following an intense muscular effort
Is reversible
What is the ∆G for PCr, and is it more energetically favourable for ATP hydrolysis or resynthesis?
-43kJ/mol
Resynthesis of ATP
Describe the power output profile during a 30s sprint
Peak power at around 3s
Power output reduced by about 45% at 25s
The fall in power matches the switch from PCr utilisation to glycolysis
What are the 2 isoforms of creatine kinase (CK), and what do each of them do?
MM-CK: responsible for regeneration of ATP
Mi-CK: part of the phosphate shuttle
What is indirect calorimetry?
A technique for calculating the contribution of carbohydrates and fat to energy provision using O2 and CO2
What happens to the contribution to energy turnover from CHO has exercise intensity increases?
Increases
What is the net production of ATP from glucose and glycogen?
2 ATP from glucose
3 from glycogen
What are the 4 key enzymatic steps in controlling glycolysis?
Glycogen –> Glucose-1-phosphate (catalysed by glycogen phosphorylase
Glucose –> Glucose-6-phosphate (catalysed by hexokinase)
Fructose 6-phosphate –> Fructose 1, 6-biphosphate (catalysed by phosphofructokinase)
Glyceraldehyde 3-phosphate –> 1, 3-diphosphoglycerate (catalysed by glyceraldehyde-phosphate dehydrogenase)
What is the creatine kinase reaction?
PCr + ADP + H+ Cr + ATP
Catalysed by creatine kinases
What are the 4 mechanisms in which skeletal muscle synthesises ATP?
Oxidative phosphorylation
Substrate level phosphorylation
Creatine kinase reaction
Myokinase reaction
What is oxidative phosphorylation?
Where mitochondria use their structure, enzymes, and energy released by the oxidation of nutrients to reform ATP
