bioenergetics Flashcards
what is enthalpy
energy contents of a system stored in the bonds. bonds broken or made changes enthalpy
chnage in H = Hproducts - H reactants
units kJ/mol
what are endothermic and exothermic reactions
endothermic - enthalpy > 0, energy taken in
exothermic - enthalpy < 0, energy released
both require energy (activation energy)
what is a spontaneous reaction
only require activation energy - exothermic reactions (endothermic reaction needs continuous energy)
what is entropy
entropy, S is a measure of how random the reactants are at the endpoint
what is free energy
free energy, G combines enthalpy and entropy - determines if reaction will happen
if change in G is negative - the reaction is spontaneous
change in G = change in H - T (change in S)
what are exergonic and endergonic reactions
exergonic reactions have negative G, release energy
endergonic reactions have positive G, take in energy
how can an exergonic reaction be achieved
increase temperature, couple reaction to an exergonic one that will outbalance the positive free energy (G)
reactions must have a common intermediate
describe metabolism
pathways in an organism, most are irreversible
if G is negative, it is energetically favourable
a high energy compound has more energy for hydrolysis - makes key intermediates. they have strained bonds which are easier to break. energy from hydrolysis drives unfavourable reactions
what is catabolism and anabolism
catabolism - breakdown provide coenzymes to anabolism turns oxidised form into reduced form energy yielding well defined products
anabolism - build up need coenzymes from catabolism requires energy well defined reactants turns reduced form into oxidised form
what is energetics
energy flow
catabolism is exergonic - produces atp
the atp is used for endergonic reactions (anabolism)
