Download Metabolism: the chemical reactions that occur in a cell

Metabolism: the chemical reactions that occur in a cell
Catabolism: complex Rx are broken down into smaller ones (release energy)
Anabolism: Rx that uses energy to assemble more complex molecule.
Amphibolic pathways: pathways that are either anabolic or catabolic
* Each Rx are catalyzed by a different enzyme
Endergonic: energy consuming
Exergonic: release energy
Aerobic: presence of O2
Anaerobic: without O2
Energy: the ability to do work
G: free energy; the energy in a system that is capable of doing work.
ΔG: G products - G reactants ( A Rx proceed only if ΔG<0 )
ΔG: the reaction is at equilibrium
The reaction always moves from a situation of high potential energy to one of lower
potential energy.
A pathway must satisfy minimally two criteria:
(1) The individual reactions must be specific. (A reaction that is specific will yield only
one particular product or set of products from its reactants)
(2) The entire set of reactions that constitute the pathway must be thermodynamically
favoured (The thermodynamics of metabolism is most readily approached in terms of free
energy. A reaction can occur spontaneously only if ΔG, the change in free energy, is
negative)
Equilibrium: rate forward equals rate reverse. Net change = 0.
Keq = equilibrium constant
* A Rx will proceed in the direction that favors an approach to equilibrium.
ΔG°’: the standard free energy change; so it will be equal to ΔG under standard
conditions (temperature (298 K), pH (7) and pressure (1atm)), concentrations of reactants
and products (1M). ΔG°’ is an indication of energy released or consumed.
If ΔG°’ is:
Negative, the reaction is exergonic; the Rx will favor the formation of products.
Positive, the reaction is endergonic; the Rx will favor the formation of reactants
*Standard free energy value are additive
Autotroph organism: is an organism that produces complex organic compounds from
simple inorganic molecules using energy from light (by photosynthesis) or inorganic
chemical reactions.
Heterotroph organism: is an organism that uses organic carbon for growth.
Respiration: sugars, form through photosynthesis, are acquired and oxidized to water
and CO2.
Oxidation: loss of electrons
Reduction: gain of electrons
Electron acceptors: NAD+ and FAD
Electron donor: NADH and FADH2
They are electron
carriers
Lactic acid: the product of glycolysis in muscle in the absence of oxygen.
Fermentation: metabolic process with organic compound as end product (in absence of
oxygen)
Kinase: enzyme that transfer y phosphoryl group of ATP to acceptor.
Hexokinase: traps glucose in cell because when glucose gets phosphorylated, it can not
leave the cell.
Phosphofructokinase: can have regulatory properties: Pacemaker enzyme.
Ubiquinone = CoQ ; mobile carrier electron. It’s lipid soluble because it stays in the
inner membrane. It’s also a proton carrier, because it carries H+.
Charge separation: move one molecule from donor to acceptor
V-snares: one type of integral membrane protein that is incorporated into the vesicle.