ATP regeneration Flashcards
how many ATP molecules are used per actin- myosin power stroke?
- 1 ATP molecule
what can hydrolysis exceed during strenuous exercise?
- exceeds 12 hexillion molecules of ATP/ min
describe the ATP- ADP cycle
- negative charge on terminal oxygen of phosphate group (PO4-) acts like a compressed spring as it repels the rest
- chemical energy is released when ATP hydrolysed> loses a phosphate molecule
is the ATP hydrolysis reaction favoured?
- thermodynamically favoured
describe anabolic reactions
- endergonic so are not thermodynamically favoured
- coupled with hydrolysis of ATP to ADP + Pi + energy to perform cellular work
describe catabolic reactions?
- exergonic> thermodynamically favoured
- release energy which can be used for ATP synthesis
what are anabolic reactions coupled to?
- the hydrolysis of ATP to ADP + Pi + energy to perform cellular work
what type of reaction is hydrolysis? is it exergonic or endergonic?
- catabolism
- exergonic
what do catabolic reactions release and what is it used for?
- release energy used for ATP synthesis
- net energy from ATP breakdown/ synthesis is manipulated to allow reactions to proceed
how much ATP is turned over by human with energy expenditure of 2000kcal per day?
- 45 kg of ATP is turned over
what can the demand for ATP hydrolysis be as high as? when does this happen?
- as high as 1kg per minute
- during strenuous exercise
what do the different metabolic pathways vary in?
- maximal rate
- sustainability
what is ATP used for during exercise?
- mechanical energy for muscle contraction
- electrical energy; electrical nerve impulses (Ca2+ pump)
- heat aids maintenance of body temperature
how long would ATP stored in muscle last?
- 3 seconds in maximal exercise
what are the accumulating breakdown products of ATP?
- ADP, AMP and PCr
describe myokinase regulation
- myokinase located in the muscle, adds phosphate group in a anaerobic reaction to maintain ATP during hard exercise
what is the maximal rate of ATP resynthesis of myokinase regulation ?
- 0.9mmmol/kg/sec
why is the reaction of ATP replenishment favoured?
- reduced ATP
- increased ADP
- AMP is broken down in liver and excreted via kidneys by adenylate deaminase
what has the highest phosphoryl transfer potential?
- phosphocreatine
describe the phosphocreatine system in muscles
- creatine kinase rapidly drives ATP synthesis during hard exercise in a cyclic process
what does phosphocreatine outweigh and why is this important?
- outweighs Cr in muscle (2:1) to favour the conversion of Cr and ATP
where is creatine located?
- near myosin head
how long does phosphocreatine stores last?
- 7 seconds during maximal exercise
what is creatine kinase maximal rate of ATP resynthesis?
- 2.6mmol/kg/s
is PCr store larger than ATP and which resynthesis is faster?
- PCr stores are 3-4 times lager than ATP
- resynthesis of PCr stores is slower than ATP
what is ATP measurement and what is the demand in exercise?
- ATP is 8mmol/kg/ s
- maximal demand during exercise is 3mmol/kg/s
what does ATP not drop below and why?
- doesn’t drop below 60% of resting levels during exercise
- due to enzymes myokinase and creatine kinase
what provides initial demand of ATP?
- phosphocreatine system
why does Pi increase and ADP increase modestly?
- because myokinase reutilises ADP
what happens beyond anaerobic pathways?
- ATP also supplied via breakdown of carbohydrates and fats
