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BioChem: Bioenergetics and Buffers


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-What is the symbol for Gibbs Free Energy?
-What is the symbol for enthalpy and entropy?
-delta G nought
-delta G nought prime
How does energy get used biologically?
-inorganics nutrients converted to organic compounds using light through photosynthetic organisms
-these organic compounds are used for energy, taken by other organisms, turned into biopolymers and wastes
What is the Gibbs free energy for a spontaneous reaction?
How about a resonant equation?
Exergonic reaction?
Endergonic reaction?
What is the delta G equation we need to know?
deltaG = deltaH - (T)(deltaS)

H is change in enthalpy
S is change is entropy
T is degrees Kelvin
What does delta G tell us?
What DOESN'T it tell us?
-tells us the spontaneity of the reaction but NOT the rate of reaction
What is the important reaction for the energy balance of a cell?
-hydrolysis of ATP
- ATP (4-) + water <--> ADP (3-) + H3PO4 (2-) + H (1+)
How are pyrophosphates bonds strained?
How are its products stabalized?
What else happens to the products?
-strain by electrostatic repulsion
-stabilization of products by ionization and resonance
-additional hydration of products
What are some energy rich compounds?
-Acyl phosphates
-Enolic phosphates
-Guanidium phosphates
What phosphates are above ATP in energy usage?
-creatine phosphate
-Phosphoenolpyruvate (most kJ/mol)
What is the first reaction to occur in phosphorylation of glucose?
Then what?
-glycolysis (13.8kJ/mol)
-hydrolysis of ATP (large negative delta G: -30.5kJ/mol)
-these reactions are coupled (energy needing and energy giving) to allow for spontaneous phosphorylation of glucose! (13.8 + -30.5 = -16.7
What is another type of couple reaction?
acetyl-CoA going to Malonyl-CoA with the treatment of Acetyl-CoA carboxylase
What is the angle found in a water molecule?
-104.5 degrees
Which bonds are strongst?
How about in between?
-Van der Waals
-hydrophobic bonding is just above Van der Waals, but well below ionic and h-bonding (these are equal)
What is the equilibrium constant for water?
-Keq = concentration of H times OH, all over water concentration
What is the concentration of pure water? Calculate this.
(1000g/L)/(18g/mol)=55.5mol/L = 55.5M
When pure water dissociates, does H or OH have a higher concentration? What is it?
How about the ion product?
-they are equal at 1 x 10^-7
-ion product is 1 x 10^-14
What is the definition of a strong acid or base?
-ionize completely in water such as HCl and NaOH
What is the definition (or equation) for a weak acid?
HA <--> H+ + A-
ex; acetic acid

Ka= [H][A]/[HA]
ka=1.76 x 10^-5
What is pH?
-a convenient expression of [H]
- pH=-log[H]
What are the two factors that buffer capacity depends on?
1)molar concentration of acid/base pair
2)ratio of the concentration of acid/base pair
What do buffers contain?
-a weak acid and its conjugate base
How would you define concentration in terms of buffers?
-the sum of the concentrations of the weak acid and its conjugate base
If [acetic acid]=[acetate]=.1M, considered a .2M acetate buffer?
How about .15M acetic acid and .05 acetate?
What is the equation one should know when dealing with pH?
pH=pka + log [A]/[HA]
Henderson-Hasselbalch equation

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