Chapter 19 - Exam 3 Flashcards
Electron Transport Chain: Basics
ETC oxidizes NADH to NAD, passing electrons from one component to another
O2 + 4e- + 4H+ = 2H2O
Where do the electrons come from?
come from NADH and FADH molecules produced during earlier stages of cellular respiration (glycolysis, pyruvate oxidation, and the citric acid cycle)
What is the importance of oxygen?
oxygen is the final electron acceptor and forms water
The components of the ETC.
- NADH-Quinone Oxidoreductase
- Succinate: Ubiquinone Oxidoreductase
- Cytochrome b, cytochrome c1, ISP (iron sulfur protein)
- Cytochrome c oxidase
- Ubiquinone
Complex 1
catalyzes two simultaneous and obligately coupled process
1. The exergonic transfer of a hydride ion from NADH and a proton from the matrix to ubiquinone
2. Proton transfer through the inner mitochondrial membrane
Complex 2
FADH2 is oxidized by ubiquinone to reform FAD (couples the oxidation of succinate with the reduction of ubiquinone)…no proton pumping
Complex 3
couples the transfer of 2 electrons from ubiquinol to cytochrome c with the vectorial transport of four protons to the intermembrane space
Net result: 2H+ are transferred to the intermembrane space from the matrix and cytochrome C is reduced
Complex 4
carries electrons from cytochrome C to oxygen…oxygen accepts the electrons and pulls 4H+ from the matrix to form water (4 protons are pumped from the matrix to the intermembrane space)
ATP Synthesis
oxidation/reduction reactions along the components of the ETC generate a proton gradient that is used by ATP synthase to phosphorylate ADP, producing ATP
Describe the chemiosmotic model.
describes the coupling of ATP synthesis to an electrochemical proton gradient (proton-motive force)
What are the two gradients that are maintained?
chemical potential and electrical potential gradients (forms a proton gradient in ETC)
ATP Synthase.
a protein that can make a large amount of ATP
the proton gradient produced during the ETC is used to synthesize ATP…protons flow down the gradient into the matrix through ATP synthase, causing it to spin and catalyze the conversion of ADP to ATP
Fo Subunit Structure and Function.
-an integral membrane protein with a proton pore
-embedded in the inner mitochondrial membrane; protons pass through the Fo transmembrane unit (acts as a mechanical driving device rotating the subunit F1, inducing conformational changes of F1)
F1 Subunit Structure and Function.
-a peripheral membrane protein
-proton movement catalyzes the release of ATP by pumping protons across the membrane to create a proton gradient
Conformational change in the B subunits catalyze ATP synthesis.
Binding-Change Model: B subunits have the ATP synthesis catalytic sites (B-ATP, B-ADP, B-empty); each complete rotation synthesizes three ATP