Lecture 1
Major Energy source for E.Coli is glucose.
•preferentially uses glucose as its main carbon source
•extracts energy and combines with inorganic compounds to carry out functions
for cellular growth and division
•uses these building blocks to convert into AA, nt, lipids, sugars, vitamins,
macromolecules (DNA,RNA,proteins, polysaccharides)
Metabolism:
•several pathways that use small fundamental components to build larger
macromolecules required for cellular processes
•uses same macromolecules to break down and provide energy
•governed by specific enzymes
Glucose>pyruvate and small molecules>
•exergonic (catabolic) reaction producing ATP
•uses ATP to build important components (Anabolic)
Energy
•ability to carry out mechanical work
•active transport of small molecules and ions
•generate macromolecules and building blocks
Energy: Ability to do work
•kinetic and potential
•potential:
ochemical bonds
oconcentration gradients
ocharge separations across membranes
•energy can be converted from one form to another
All chemical reactions are reversible
Equilibrium: rate forwards = rate reverse
• k_1[A][B] = k_2[C][D]
•products/reactants = k1/k2 = k_eq
Free energy or G
•Reaction proceeds only if ∆G<0
•∆G>0, reaction from right to left
•∆G = 0 , equilibrium
Standard free energy
•∆Gº < 0 ; exergonic (energy releasing)
•∆Gº > 0 ; endergonic (energy consuming)
•∆Gº (from A to B) = -∆Gº (From B to A)
•∆Gº (A to C) = ∆Gº (A to B) + ∆Gº (B to C)
Lecture 2 Metabolism II
Rate of reaction depends on reactants involved
so we must know characteristics of reactants
As reaction proceeds, concentrations of A decreases as concentratoin of B is formed
Catalysis
•changes energy required to form a critical transition state
•transition state of any chem reaction is when reactants come together in
favorable manner to drive the reaction to form products
•enzymes or any catalysts decreases the amount of free energy to achieve
transition state between reactants
Enzymes
•specific catalysts for bio reactions
•act by binding to reactant(s) [substrates] in a way that reduces the energy
required to reach transtition state
•enzymes affect only the rates of reaction-
oother properties (e.g. Keq and ∆G emain the same)
•by forming binding pocket, substrate can interact with its enzyme
oenzyme substrate complex… we can achieve products with much less
energy input
owe favor the formation of products
E + S<--> ES --> E + P
Rates of enzymatically catalyzed rxns approach a maximal velocity as substrate
concentration increases
i.e. any enzyme has a specific maximum velocity/capacity to form products
Vmax
•Vmax is dependent on amount of enzyme in solution-so Vmax doesn't tell us
much
•BUT the HALF-MAX value (i.e. Vmax/2), we have a value at which the
enzyme produces at half its maximal velocity
•the HALF MAX value (Km - Michaelis constant) is a characteristic of the
enzyme
•describes the affinity of the enzyme for the substrate
If we plot enzyme activity on Lineweaver-Burk plot
•double reciprocal plot
•y intercept = 1/Vmax
•x intercept = -1/Km
•slope = Km/Vmax
Energy from breakdown of food into smaller molecules is captured b coupling
specific rxns to ATP synth and through the process of OXIDATIVE
PHOSPHORYLATION
ATP generated in cell is used for many processes (i.e. mechanical)
Lecture 4 - Photosynthesis
Photosynthetic organisms (Phototrophs) capture light energy and use it to:
•transfer H atoms from water to acceptor molecules
•form molecular oxygen
•synth ATP from ADP and P
•transfer H atoms from acceptor to carbons derived from CO2 to form glucose