L2: Bioenergetics & L2B: ATP Flashcards
what is bioenergetics
the quantitative study of energy transductions in living cells, organisms, systems
What must rxns in metabolism be (2)
- Specific - must recognise substrate & produce product
- Thermodynamically favourable - must be able to go ahead
what is thermodynamics in biology considered in terms of
Change in Gibbs free energy - delta G’0
what is delta G’0 if rxn at equilibrium
0
what is the rxn like if delta G’0 is negative
- rxns is exergonic
- releases energy
- proceeds spontaneously
- proceeds forward
what is rxn like if delta G’0 is positive
- rxn is endergonic
- requires energy input
- rxn cant occur spontaneously
delta G’0 is another way of expressing what
K’eq - the equilibrium constant
tells us how far from equilibrium a rxn is
K’eq = conc of product divided by conc of reactants
why is delta G’0 a constant value
chem rxns in cells have characteristic delta G’0 under standard conditions so delta G’0 a constant value
what are actual free energy changes based on
real conditions & real [reactants] and [products]
how can thermodynamically unfavourable rxns be driven
-can be driven by thermodynamically favourable ones
-can be coupled
what pathways produce ATP
catabolic
what pathways use ATP
anabolic
what happens if cells dont keep ATP conc constant
changes in homeostasis - cell death
the cleavage of what bond in ATP causes energy to be releases
phosphoanhydride bonds
what charge is in the phosphates & why
- strong neg charge to repel eachother
- phosphoanhydride bonds ready to break & release energy
what kind of rxn breaks the phosphoanhydride bonds
hydrolysis
what is the delta G’0 value for ATP hydrolysis & energy transfer
-30.5 kJ/mol
where does ATP synthesis occur
mitochondria
how does oxidative phosphorylation work
ATP synthase synthesises ATP in the presence of O2
* phosphorylation = addition of phosphate to ADP to make ATP
where does substrate level phosphorylation occur & w what enzyme
occurs in cytosol w kinase enzyme
what other molecules have large free energies of hydrolysis to drive metabolic processes
- phosphorylated: phosphoenolpyruvate (PEP), phosphocreatine
- non phosphorylated: thioesters like acetyl-CoA
ATP functions
- cell division
- biomolecule synthesis
- muscle contraction
- transcription & translation
- cell signalling
