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?
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-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? -
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0
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>0 - What is the delta G equation we need to know?
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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?
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-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?
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-pyrophosphates
-ATP
-Acyl phosphates
-Enolic phosphates
-Guanidium phosphates
-Thioesters - What phosphates are above ATP in energy usage?
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-pyrophosphate
-creatine phosphate
-1,3-Bis-phosphoglycerate
-Phosphoenolpyruvate (most kJ/mol) -
What is the first reaction to occur in phosphorylation of glucose?
Then what?
Lastly? -
-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
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Which bonds are strongst?
Weakest?
How about in between? -
-covalent
-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
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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?
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HA <--> H+ + A-
ex; acetic acid
Ka= [H][A]/[HA]
ka=1.76 x 10^-5 - What is pH?
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-a convenient expression of [H]
- pH=-log[H] - What are the two factors that buffer capacity depends on?
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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
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If [acetic acid]=[acetate]=.1M, considered a .2M acetate buffer?
How about .15M acetic acid and .05 acetate? -
Yes
Yes - What is the equation one should know when dealing with pH?
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pH=pka + log [A]/[HA]
Henderson-Hasselbalch equation