Lecture notes APES1001A

Block 3 Notes:


L1
Metabolism  The sum of all chemical reactions in a cell
Differentiating between catabolic and anabolic reactions:




Catabolism Breaking down of molecules
Anabolism Synthesis of molecules
2nd law of thermodynamics: Every energy transfer increases disorder (entropy) of
the universe.
-ΔG= spontaneous reaction
A process is spontaneous and can perform work only when it is moving toward
equilibrium.


Hydrolysis of ATP: Breaking a phosphate bond through the addition of water

,ATP Powers cellular work:
Type of work Example:
Chemical work Pushing of endergonic reactions
Transport work Pumping of substances across a
membrane
Mechanical work Contraction of muscle cells


Regeneration of ATP:
 ATP is a renewable resource that can be regenerated by addition of phosphate
to ADP
 Energy from catabolism (exergonic, energy-releasing processes)  energy for
cellular work (endergonic, energy-consuming processes)


Enzymes:
 Spontaneous reactions can be slow
 Enzyme= macromolecule (usually protein) that is a catalyst to reactions

,  Biological catalyst that speeds up a reaction without being consumed by the
reaction.


Activation energy:
 Energy required to break the bonds of the reactant molecule




 Acting as a template for
substrate orientation
 Stressing the substrate &
stabilizing the transition
state
 Providing a favourable
microenvironment
 Participating directly in the
catalyst reaction




Optimal Conditions:

, L2
Redox reactions:
 Reduction gain of electrons
 Oxidation loss of electrons
 Reducing agent becomes oxidised
 Oxidising agent becomes reduced
Cellular respiration:




 Electron carrier or coenzyme NAD+ (Nicotinamide adenine dinucleotide)
functions as an oxidising agent during respiration
 oxygen is the final electron acceptor in cellular respiration
 GlycolysisPyruvate oxidationcitric acid cycleOxidative phosphorylation
 32 ATP from cellular respiration