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431 - Exam 1 Review Questions and Answers
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431 - Exam 1 Review Questions and Answers
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431 - Exam 1 Review Questions andAnswers
1st law of thermodynamics - Answer-- Energy can be transferred and transformed, but it
cannot be created or destroyed.
∆E = Efinal - Einitial = heat(q) - work(w)
2nd law of thermodynamics - Answer-- All spontaneous processes lead towards entropy
(S) in the absence of energy input
∆Suniverse = ∆Ssystem + ∆Ssurroundings > 0
Enthalpy (H) (endo vs exo) - Answer-Endothermic
- Absorbs heat
- +∆H
Exothermic
- Releases heat
- -∆H
Entropy (S) - Answer-A measure of disorder
More dispersal means greater entropy
Gibbs Free Energy (equation, endo vs exo) - Answer-G = H - T·S
- At equilibrium, G=0
Exergonic
- Spontaneous
- ∆G<0
- Forward Rxn
Endergonic
- Nonspontaneous
- ∆G>0
- Reverse Rxn
Standard Free Energy Change - Answer-∆G° = ∆H° - T·∆S°
- at 1 atm, 298 K, [reactants] = [products] = 1 M
∆G° = -R·T·ln(Keq)
, - Keq < 1 favors reactants
- Keq > 1 favors products
- Keq = 1 is in equilibrium
Anabolism - Answer-- Building stuff up when there's high EC (use ATP)
Catabolism - Answer-- Breaking things down to maintain EC (Generate ATP)
- E rich compounds --> energy poor compounds
Water properties - Answer-- Polar
- Ionizable
- Universal solvent due to its H-bonds
- Less dense as a solid
Hydrogen Bonding - Answer-Bonds between an EN donor group's H-atom and another
EN atom
Ionic bonding - Answer-Bonds held together by oppositely charged atoms
Hydrophobic interactions - Answer-- Hydrophobic regions cluster together away from
water to minimize the hydration layer
- Between nonpolar amino acids which don't form H-bonds with water
- Important in protein folding
Kw - Answer-The ionization constant of water = 1.0*10^-14
Henderson-Hasselbalch equation - Answer-pH = pKa + log [A-]/[HA]
Alpha Helix - Answer-- Right handed
- Helix stabilized by H-bonds
- 3.6 residues per turn
- Both + and - charges present
- Amphipathic
Beta Sheets (Strands) - Answer-- Held together by H-bonding
- Antiparallel configuration has less bond strain
Beta Turns - Answer-- Connect the strands of a beta sheet
- Glycine is most common beta turner, so it contributes the MOST torsional strain
- Type 1 configuration has less strain
4 classes of Tertiary Structures - Answer-- Alpha-helices
- Beta sheets
- Alpha/beta tertiary
- A + B structure
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