biochem exam review

biochem exam review - 3 domains of organisms Bacteria,...

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3 domains of organisms Bacteria, archaea, eucarya Elements that compromise organisms - H, O, C, N= 99% of human body o Cations/anions Blood plasma/Interstitial fluid (Na + , HCO 3- , Cl - ) Cell fluid (K + , HPO 42- ) Macromolecules o From building blocks Amino acids proteins, monosaccharides (sugars) polysaccharides, nucleotides nucleic acids, fatty acids and glycerols lipids o Have directionality o Have characteristic 3D architecture Names and structures of functional groups in biomolecules Different types of weak interactions and their energies; H-bond characteristics o Weak forces Mediate biomolecular recognition Restrict organisms to narrow range of environmental conditions Note the E(r)
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Favorable bond energies are negative in value Energy of and reason for hydrophobic interactions Strength = <40kJ/mol Entropy-driven due to a net decrease in order among the water molecules
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Decrease in entropy when water forms clathrate structure around nonpolar molecules Nonpolar molecules associate to reduce surface area minimizes decrease in entropy Principal buffers in blood and cells Blood plasma/interstitial fluid: CO 2 -bicarbonate system (HCO 3- /H 2 CO 3 ) Cell fluid: phosphate system (HPO 42- /H 2 PO 4- ) Meaning of Ka and pKa; use in determining pH of weak acid solutions Acid dissociation constant (K a ) and pK a o pK a = -logK a o K a = [H + ][A - ]/[HA - ] = [H + ] 2 ./ [HA - ] [HA - ] o – [H + ] Use quadratic equation to find [H + ]. Use [H + ] to find pH. How pKa values can be changed by environment Henderson-Hasselbalch eq o pH = pK a + log[A - ]/[HA] o Use to find pH for mixture of weak acid and its conjugate base, or amount of weak acid and conjugate base for given pH Meaning of buffer zone A substance that minimizes change in the acidity of a solution when an acid or base is added to the solution Determination of pI for polyprotic weak acids 1 st and 2 nd laws of thermodynamics o 1 st Law = energy is neither created nor destroyed, only changes its form ΔE = q – w (q stands for heat, w for work) o 2 nd Law = systems tend toward disorder, entropy unchanged, processes occur towards equilibrium Meaning of H,S, and G o ΔH = enthalpy, heat transferred under constant pressure o ΔS = entropy, disorder o ΔG = Gibbs free energy, amount of useful work obtained from a chemical process Definitions in thermodynamics Endothermic- (system absorbs E) Exothermic- (system releases E) Endergonic- (ΔG>0, reaction is unfavorable) Exergonic- (ΔG<0, reaction is favorable and spontaneous) Amphipathic/amphiphilic- (has both polar/hydrophilic and nonpolar/hydrophobic parts) Examples: fatty acids, detergents, and most common AAs
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Micelle -(globular formation of amphiphilic molecules in aqueous environment) Why H and S tend to counteract one another in aqueous solutions The formulas of thermodynamics Meaning of ΔG’ and ΔG°’ o ‘ = at pH 7.0 o ° = at standard state (25
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biochem exam review - 3 domains of organisms Bacteria,...

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