BIOC405 LECTURE 22 EXAM QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS VERIFIED

BIOC405 LECTURE 22 EXAM QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS VERIFIED What is ATPase driven by? protons going back down their concentration gradient made by ETC What is the reason for ETC to make H+ gradient? makes transporting H+ back to matrix thermodynamically favorable Which makes a greater contribution to ATPase: H+ concentration gradient or electrical gradient? why? electrical gradient bc protonation and re-ionization of a glutamate in c-ring subunits drives rotation ____ H+ are pumped out of matrix for each pair of e- that enters ETC from NADH 10 What are the different domains of ATPase? How many subunits do they have? a-subunit: 1 c-ring: 8-15 (11 in mammals) Stator: 4 y, δ, ε: 1 each αβ dimers: 3 (6 total) Which domains of ATPase are stationary? which rotate? stationary: Stator + αβ dimers + a subunits rotate (known as rotor): c-ring, y δ ε subunits What happens if you feed ATP to ATPase? it will spin backwards and hydrolyze it to ADP describe the process of ATPase getting H+ into matrix 1. wandering H+ in intermembrane goes thru a-subunit channel, and meets glutamate (which is usually - charged) and protonates it 2. once protonated, it's still polar, but now uncharged. This allows glutamate to be happy enough to enter lipid bilayer (so whole thing rotates so glutamate faces the membrane) - remember, this wouldn't happen if glutamate was - charged bc entering hydrophobic bilayer is highly unfavorable 3. after this, the next glutamate comes in to accept a H+ and repeat sequence. 4. Once original glutamate goes around and reaches 2nd half channel of a-subunit (connected to matrix), there's an arginine residue in the half channel waiting for it. * remember, Arg is + charged and that convinces glutamate to lose its H+ and become - charged to create electrostatically favorable interaction (H+ goes into matrix thru half channel) describe process of ATPase using H+ from matrix to form ATP