MCBG energy topic 5 Flashcards
Which phosphate group on ATP is hydrolyzed when energy is needed to drive cellular work?
gamma
When ATP levels are high in skeletal muscle, energy may be temporarily stored in which substance?
Phosphocreatine (creatine phosphate)
used to store “phosphate” bond energy
used in the first few seconds of vigorous exercise.
Compare and contrast catabolism and anabolism
Catabolism
- oxidative
- produces high energy compounds (energy releasing enabling)
- produces intermediates
- large negative Gibbs free energy
- +ve entropy change (degenerative)
Anabolism
- reductive
- energy consuming
- consumes intermediates
- small negative Gibbs free energy
- -ve entropy change (biosynthetic)
list fuel molecules
- fatty acids
- ketone bodies
- glucose
- glycerol
- amino acids
- alcohol
- lactate
which reaction is catalysed by creatine kinase.
when does this occur?
Creatine phosphate + ADP ↔ ATP + creatine
backwards reaction
when high [ATP] drives synthesis of Creatine Phosphate.
Role of creatine phosphate?
act as a small store of free energy in muscle cells
- ATP generated by reversible reaction
- important in first seconds of vigorous muscle activity e.g. sprinting.
Role of ATP?
- ATP acts as a carrier of free energy
- energy is conserved as chemical bond energy (covalent bond that links the terminal phosphate group to the rest of the ATP molecule)
- energy released when phosphate group removed by hydrolysis
- ATP must be rapidly resynthesised from ADP (cycle) using the free energy from catabolism of fuel molecules.
example of biosynthetic reaction involving reduction step
fatty acid and cholesterol synthesis require NADPH (biosynthetic reducing power)
role of CNS in energy metabolism
energy sources and storage
- Energy from glucose (also ketone bodies under certain conditions).
- No fuel storage > requires continuous supply of fuels and oxygen.
role of heart muscle in energy metabolism
source and storage
- Energy from glucose, lactate, fatty acids or ketone bodies.
- No fuel storage > requires continuous supply of fuels and oxygen.
role of skeletal muscle in energy metabolism
- Energy from glucose, fatty acids or ketone bodies.
- Stores glucose as glycogen and some triacylglycerol.
- Muscle protein can be used in emergency.
• Can oxidise glucose to lactate under anaerobic
conditions.
role of liver in energy metabolism
- Energy from fatty acids, amino acids or alcohol. Can use galactose and fructose.
- Stores glucose as glycogen.
- Makes glucose from lactate, glycerol and amino acids.
- Makes ketone bodies, cholesterol and triacylglycerol.
role of Adipose tissue in energy metabolism
- Energy from glucose or fatty acids.
* Stores fuel in the form of triacylglycerol.
why does cardiac arrest affect the heart and CNS more rapidly than skeletal muscle.
heart and CNS
- no oxygen or fuel store > require continuous supply
- VERY limited capacity for anaerobic metabolism
skeletal muscle
- store fuel and glycogen
- store O2 as myoglobin
- limited capacity for anaerobic metabolism (~5mins)
why does disruption of the fuel and oxygen supply to heart and CNS cause damage?
inability to maintain intracellular ATP levels
- reduced functional activity
- failure to maintain ionic gradients (Na+ and K+)
- reduced membrane stability
> structural damage.
