Energy Reactions In Cells Flashcards
(18 cards)
Metabolism
The set of processes which derive energy and raw materials from food stuffs and use them to support repair, growth and activity of tissues of the body to sustain life.
Catabolic pathways
Break down larger molecules into smaller ones.
Release large amounts of energy.
Oxidative - release H atoms.
Anabolic pathways
Synthesise larger important cellular components.
Use energy released from catabolism (ATP).
Reductive - uses H atoms
Energy in metabolism?
Chemical bond energy
Exergonic
Releases energy
Endergonic
Requires energy
Gibbs free energy of exergonic reactions
Gibbs free energy < 0
Energy of reactants > energy of products
Gibbs free energy of endergonic reactions
Gibbs free energy > 0
Energy of reactants < energy of products
H-carrier molecules
Coenzymes that act as carriers of reducing power (H atoms).
Adenylate kinase
Switched on when ATP levels are dropping; catalyses 2ADP -> ATP + AMP.
High energy signals
ATP
NADH
NADPH
FAD2H
- these activate anabolic pathways
Low energy signals
ADP
AMP
NAD+
NADP+
FAD
- these activate catabolic pathways
What regulates gene expression, changing anabolic processes to catabolic pathways?
AMP dependent kinase
Activated by AMP (and ADP).
Creatine phosphate
Used as a reserve of high energy stores.
It is formed when ATP concentrations are high, and the reaction is reversed when ATP levels fall, providing a short term boost to ATP conc.
Creatine phosphate reaction
Creatine + ATP <ā> Creatine phosphate + ADP
Catalysed by creatine kinase
Creatine kinase
Enzyme that catalyses formation of creatine phosphate.
Used as a marker for muscle damage eg cardiac muscle damage in MI. However it is not very specific, so cardiac specific trope in tests are preferred.
Can still be used for suspected muscle injury or unexplained muscle weakness (myopathy).
Isoforms on CK
3 combos possible, as CK is made of two subunits, M and B.
- MM, BB and MB
CK-MB is used as a marker for muscle damage.
Creatinine
Breakdown product of creatine and creatine phosphate.
Usually produced at a constant rate, unless the muscle is wasting.
It is excreted via kidneys, so can be used to assess kidney function.
Conc. in urine is marker of urine dilution.
