Unit 3 - Thermodynamics & Enzymes Flashcards
First Law of Thermodynamics
-energy can be transferred and transformed, but it cannot be created nor destroyed
Second Law of Thermodynamics
-energy tends to disperse spontaneously
localized and ordered to spread out and disordered
Exergonic Reactions
- occur spontaneously (gibbs free energy is negative)
- net release of energy
- energetically favourable reaction
Endergonic Reactions
- does not occur spontaneously (gibbs free energy is positive)
- net input of energy required
- energetically unfavourable reaction
Coupling of Reactions
- can occur if reactions share one or more intermediates
- unfavourable reaction can be driven by second, highly favourable reaction
- cells cannot undergo endergonic reactions, must find a way to do them exergonically
Collisions are influenced by…
- how fast molecules are moving - temperature
- how crowded they are - concentration
Enzymes
- catalyze thermodynamically favourable reactions
- allows reactions to proceed at rapid rates
- accelerate and control rates of vitally important biochemical reactions
- DO NOT CHANGE: thermodynamics, equilibrium, catalyze non-spontaneous reactions, endergonic reactions
Activation Energy
-energy required for reaction to proceed/start
enzymes lower a.e. of exergonic reactions so that they can proceed
Enzyme Cofactors
-some enzymes bind to non-protein factors to ‘help’ them do required chemistry they cannot do on their own
-inorganic & organic
chemically changed during the reaction
- must be regenerated to complete catalytic cycle
Non-competitive inhibitors
-bind to allosteric sites, changing enzyme’s confirmation so that the substrate no longer fits
Competitive inhibitors
-competes with substrate to bind to active site so that the substrate cannot bind
Covalent Modification
- phosphorylation occurs at the -OH containing side chains
- to add phosphate group –> add kinase
- to remove phosphate group –> need phosphatase
