ATP Flashcards
Anabolism
synthetic reactions
genesis
glycogenesis
Catabolism
breakdown reactions
lysis
glycolysis
Why is metabolism important?
Energy is required for:
- motion
- transport
- biosynthesis
- thermoregulation
Cells requires sources of free energy
maintaining life requires constant investment in energy, when a cell can no longer obtain energy it dies and decays
- free energy is energy available to perform work and is
accquired from nutrient molecules
C6H12O6+6)2->6CO2+6H2O+ energy
Enthalpy (H)
the heat content of the reacting system
Entropy (s)
the randomness or disorder in a system
Gibbs Free Energy
energy capable of doing work at a constant temp and pressure
In cells the enthalpy change (deltaH) reflects
- the chemical bonds broken and formed
- delta H is positive when energy is absorbed by the
reaction (endothermic)
In cells the change in entropy (delta S) describes
the formation of large complex proteins from smaller molecules or vice verse
- delta S is positive when randomness increases
(breaking a bigger molecule into smaller molecule)
Gibbs free energy equation
For a reaction to occur spontaneous delta G must be
negative (energy is released by the reaction)
Catabolism is endergonic or exergonic
exergonic
products have less free energy and so are more stable than the reactants
exergonic reactions
endergonic reactions
Coupling of reactions:
an endergonic reaction can be driven in the forward direction by coupling it to an exergonic reaction
the hydrolysis of ATP provides the energy to drive an unfavourable reaction
ATP is the energy currency of the cell
achieved by phosphate group transfer
Substrate level phosphorylation
- formation of ATP by the transfer of a phophoryl froup
from a substrate to ADP - distinguished from respiration linked phosphorlyation
- substrate level phosphorylation requires soluble
enzymes and chemical intermediates - respiration linked phosphorylates involve membrane
bound enzymes and transmembrane gradients of
protons and require oxygen
Enzymes influence the delta G of the reaction.
True or False?
False
DOES NOT INFLUENCE DELTA G
cofactors and coenzymes
prosthetic groups
- non-protein cofactor that is covalently bound to the
enzyme - not released as part of the reaction
- acts as a temporary store for e—– or reaction
intermediates