MCAT chem1* – Flashcards
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| -? H +? S |
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| -? G, spontaneous at all temps |
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| +? H -? S |
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| +? G, non-spontaneous at all temps |
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| -H -S |
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| spont. at low temps |
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| +? H +? S |
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| spont. at high temps |
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| if delta G is negative what does it tell you about energy and speed of rxn |
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| exothermic cannot tell anything about how fast rxn is, |
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| -? G, then Keq favors |
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| +Keq products |
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| +? G, then Keq favors |
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| -Keq reactants |
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| G=0, then Keq favors |
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| Keq=1 equilib |
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| Eqn for Gibbs free energy |
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| ?G= ?H-T ?S |
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| Gibs energy eqn std in a cell where molarities arent 1 |
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| ? G*=-RTlnKeq |
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| catalyst |
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| lowers Ea in both directions by stabilizing Transition state |
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| what does catalyst do to equilibrium |
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| does not shift/mess with it |
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| higher Km means -- substrate |
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| lower affinity for S |
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| Km= |
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| 1/2 vMax |
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| competitive inhibition |
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| inhibitor binds to active site |
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| competitive inhibition effect on Km and Vmax |
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| increases Km doesn't change Vmax |
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| Non-competitive inhibition |
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| inhibitor binds not at active site |
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| non- competitive inhibition effect on Km and Vmax |
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| Km does not change Vmax is lowered |
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| Cooperativity |
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| binding of one substrate increases affinity for the next substrate to bind |
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| cooperativity has a -- curve |
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| sigmoid |
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| Hb vs Mb |
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| Hb has 4, where Mb (muscle) only has 1 subunit and therefore Mb does not have cooperativity |
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| Bohr effect- |
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| prescence of H+ and CO2 decrease Hb affinity for O2 causing Hb to release O2 in the tissue. This shifts the sigmoid curve to the right |
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| Pressure of O2 is highest in |
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| lungs, causing the high % saturation of Hb to pick it up and deliver to tissue where PO2 is lower to release it |
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| allosteric regulation |
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| not active site, feedback inhibition |
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| phosphorylation |
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| covalent modification by adding a phosphate it adds - charge |
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| AA with an OH group that can be phosphorylated |
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| Ser, Thr, Tyr |
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| Kinases or phophorylations |
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| add phosphate kinase- ATP hydrolysis |
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| phosphatases |
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| dephosphorylate enzymes, take phosphate off |
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| what does phosphorylation do to the enzyme |
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| changes the confirmation, either activating it or deactivating it. |
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| Zymogens |
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| inactive precursors that become active w/proteolytic cleavage ex: digestive enzymes trypsin and chymotrypsin |
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| Cofactors |
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| enzyme regulation with the use of metal ions or coenzymes |
