PHSC 208, L29

iClicker: Consequence of antimyicin exposure on mitochondrial function and electron carriers in isolated mitochondria?

a. increased ATP synthesis

b. enhanced O2 consumption

c. accumulation of oxidized Cyt C

d. accumulation of NAD+

e. accumulation of FAD+

c. accumulation of oxidized Cyt C

Where is ATP synthesized in the complexes?

at Complex V

Chemiosmotic Theory is

the energy obtained from ETS was being stored and used later to make ATP

Protonmotive force is…

the energy generated by ETS from the proton gradient (high concentration to low concentration) to move protons out of matrix into inner mitochondrial membrane

Who is Peter Mitchell?

• proposed the chemisomotic hypothesis which explains how electron transport stored energy could be used elsewhere to make ATP, but stored energy could not be isolated from mitochondria

• won Nobel Prize in chemistry, 1978

More evidence that supports Chemiosmotic Model

• pH outside the inner mitochondrial membrane lowers during aerobic respiration

• ATP synthesis by mitochondria stops when membrane is physically disrupted

• uncouplers: molecules that allow protons into mitochondria inhibit ATP synthesis (DNP, gramicidin)

F1 domain

• contains catalytic activity and sticks into matrix

• responsible for ATP synthesis— H+ protons flow through F0 and generates PMF, and rotates itself leading to ATP synthesis

• located outside of membrane

F0 domain

• drives rotation of F1

• protons pass through F0 and the protons’ rotation drive catalysis

• subunits: c10/a/b2

  “proton driven wheel”

Stator Domain

b2 and δ

“rigid arm to stabilize F1 domain”

αβ OPEN state

no substrate binding

αβ LOOSE state

weak substrate binding (priming)

αβ TIGHT state

undergoes catalysis

iClicker: What is the intermediate form of energy generated by electron transport that is used to make ATP?

a. water gradient across the outer mitochondrial membrane

b. ADP gradient across the outer mitochondrial membrane

c. gradient of protons across the inner mitochondrial membrane

d. a spring-like structure with torsional energy that is used to rotate a supramolecular structure

e. phosphorylated proteins that line the inner mitochondrial membrane

c. gradient of protons across the inner mitochondrial membrane

O2 consumption in purified mitochondria and give ADP…

it speed up oxygen consumption— ADP is regulating process

What is the function of ADP levels?

respiratory control regulates ATP synthesis

What happens to the electron transport system when ATP is high/ ADP is low?

ETS and citric acid cycle slows down

ATP is an ______ inhibitor of ETS at Cyt C oxidase (complex IV)

allosteric

What are ATP and ADP in the mitochondrial matrix controlled by?

ADP-ATP translocaters and phosphate translocase