BIOSC 1000: FINAL EXAM
20 Cards in this Set
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acid strength
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tendency to release a proton
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Ka
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equilibrium constant for an ionizing acid: ionization constant, measured by titration of the pH
Doesn't change with changes in pH, depends on the chemical structure and environment of the acidic group
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equivalence point
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complete deprotonation has occured, the amount of added base is equal to the total number of ionizable protons in the weak acid. Can be used to determine the concentration of the acid
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inflection point
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where the pH=pKa for the acid. [HA]=[A-]. pH changes most slowly when added near this point (buffer zone)
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zwitterion
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have no net charge, both amino and carboxyl groups are ionized around pH-7; can act as proton donors or proton acceptors
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enantiomers
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mirror images that cannot be superimposed; identical physical, chemical properties but different biological properties
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maple syrup urine disease
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defect in enzyme that breaks down branched chain AA (Leucine, isoleucine, and valine); leads to build up of AA
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phenylketonuria (PKU)
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defect in the metabolism of phenylalanine leading to buildup of metabolites; painful condition can be controlled by diet
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peptides
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chains of AA residues linked by amide bonds formed by condensation reactions between carboxylic acid and amino groups of amino acids
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Edman degradation procedure
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determining one residue at a time from the n-terminus
proteases are used to selectively cleave the protein into smaller fragments
trypsin- cleaves at the carbonyl side of basic residues (lys, Arg)
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sickle cell anemia
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E6V, Glu to Val mutation at AA position 6
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Ion exchange chromatography
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separates proteins based on net charge; anion exchange attracts negative charged ions, cation exchange is a negatively charged column that makes positively charges stick
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Gel electrophoresis (SDS-PAGE)
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separates based on size, migration depends on molecular weight regardless of charge; small proteins migrate further
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affinity chromatography
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most selective purification strategy that uses a specific ligand binding so that unwanted proteins are washed through colomn
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gel filtration chromatography
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large proteins elute first as smaller proteins get stuck in pores
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Kd
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(1/ka); represents the concentration at which 50% of total possible ligand binding sites are occupied; lower Kd means higher affinity of ligand for the protein
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Bohr Effect
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Allosteric regulation of Hb; as [H+] and CO2 increase in tissues, a decrease in pH is seen which leads to a diminished affinity of Hb for O2. This leads to release of O2 into blood and tissues. In the Lungs, the pH increases as CO2 is expelled. This increases the affinity of Hb for O2, le…
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Myoglobin
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stored supply of O2 in the muscles; more tightly bound than in Hb; oxygen binding doesn't induce any significant structural change; hyperbolic curve
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Hemoglobin
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4 heme groups, shows cooperative/sigmoidal binding to O2; O2 has highest affinity for R state; binding of O2 at the first site affects the affinity of the other sites for O2
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Km
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describes the dissociation constant for a substrate with its enzyme; [S] where V=.5Vmax
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Exam 1