Chapter 18 - Oxidative Phosphorylation

What is oxidative phosphorylation?

the process by which ATP is formed as electrons are transferred from NADH to O2

Where does oxidative phosphorylation occur?

inner mitochondrial membrane

what do the respiratory assemblies contain?

electron carrier and proton pumps

What is the free energy and electrical potential formula?

Delta G standard' = -nFE0

N=number of e- transferred

F=faraday constant= 96.48 kJ/v-mol

E0= electrical potential (+ for spontaneous)

How are partial reactions written?

oxidant + e- to reductant

What happens to NADH and FADH2 in the mitochondria during oxidative phosphorylation?

NADH is oxidized back to NAD+ and FADH2 is oxidized back to FAD

FMN

flavin mononucleotide

what is a cytochrome?

a protein that transfers electrons and that also contains a heme prosthetic group

What is the are the central metal atom for the three cytochromes a, b, and c?

Fe for b and c, Cu for a

How many complexes are the electron carriers organized into?

four

How are the transmembrane complexes arranged?

so that each successive reaction has a more positive E0… more spontaneous

What is complex 1 of the transmembrane complexes?

NADH-Q oxidoreductase

What is the net reaction for complex 1: NADH-Q oxidoreductase?

NADH + CoQ + 5H+(matrix)---> NAD+ + CoQH2 + 4H+(transmemspace)

What is complex 2 of the transmembrane complexes called?

succinate-Q reductase

What do SDHC and SDHD do in complex 2?

they are hydrophobic proteins that bind the complex to the membrane and include cytochrome b

What is complex 3 of the transmembrane complexes called?

Q-Cytochrome C oxidoreductase

What type of cytochromes does complex 3 contain?

bH and bL (for high and low affinity)

What is complex 4 of the transmembrane complexes called?

cytochrome oxidase

What does it mean for a complex to be transmembrane?

it means it touches both the matrix and intermembrane space

What are proton pumps?

Protein complexes that pump protons through a membrane

What is the chemiosmotic hypothesis?

protons pumped across membrane create proton gradient, which powers ATP synthesis

how are the electron transport chain and ATP synthase linked?

the proton gradient

What are the two components of ATPase?

F0 located in the membrane and F1 which protrudes from the membrane into the matrix

What are the three binding modes for the 3 beta subunits in ATP synthesis?

O=open- low affinity for substrate

L=loose-catalytically inactive, loosely binds substrate

T=tight-catalytically active, binds substrate tightly

Which binding mode goes to which during proton flux? What does each binding mode do during ATP synthesis?

O-->L

L-->T

T-->O

O releases ATP, L binds ADP and Pi, T converts ADP and Pi to ATP

On what side of the mitochondria is ATP synthesized?

the matrix side

What transports the ATP and ADP in and out of the mitochondria?

ATP-ADP translocase

How much ATP comes from one glucose?

30 ATP

How much ATP is yielded from oxidative phosphorylation?

26 ATP

What does the glycerol-3-phosphate shuttle do?

it brings NADH into the matrix to give 1.5 ATP per NADH

What is the net reaction of the glycerol-3-phosphate shuttle?

NADH + H+ + E-FAD ---> NAD+ + E-FADH2

What does the malate-aspartate shuttle do?

transports NADH into the matrix to give 2.5 ATP per NADH

What is the net reaction of the malate-aspartate shuttle?

NADH + NAD+ --> NAD+ + NADH

What are the inhibitors of the electron transport chain?

rotenone, amytal, antimycin A