Card Set Information
MCDB 310- Chapter 19 notes
Overview of oxidative phosphorylation:
Catabolism of carbohydrate, lipid, amino acids converge on Cellular Respiration.
Electrons donated by NADH and FADH2.
Happens in mitochondria
Overview of photophosphorylation:
The process by which sunlight is captured and used to drive ATP synthesis - Absolutely requires light.
Involves oxidation of H2O to O2
NADP+ is the final electron acceptor
Happens in chloroplasts
NAD+ and NADP+
FAD and FMN
Universal electron carriers:
Ubiquinone (Coenzyme Q)
Ubiquinone (coenzyme Q):
long isoprenoid side-chain
shuttles electrons between various carriers.
Accepts one electron (semiquinone radical) or two (ubiquinol)
Contain iron-heme groups.
Tightly, but non-covalently, associated with the protein.
Most are integral proteins of the inner mitochondrial membrane.
What are the three classes of cytochromes:
Iron protoporphyrin IX (in b-type cytochromes).
Heme C (in c-type cytochormes).
Heme A (in a-type cytochromes).
Iron is associated with inorganic sulfur or Cys sulfur (not heme sulfur).
Participate in one-electron transfers.
Rieske iron- sulfur protein iron coordinates with 2 His instead of 2 Cys.
Sequence of electron transport in the respiratory chain:
electrons move from NADH, succinate, or other donors to..
Ubiquinone (coenzyme Q)
cytochromes (and copper centers)
molecular oxygen (final electron acceptor)
ECT complex names:
Complex I = NADH dehydrogenase
Complex II = succinate dehydrogenase
Complex III = cytochrome bc1
Complex IV = cytochrome oxidase
Phosphates transferred (P) to oxygens oxidized (O).
2.5 [10 protons pumped out per pair of electrons transferred/ 4 - number of protons required to drive the synthesis of 1 ATP
Succinate P/O ratio:
1.5 [ 6 protons pumped – electrons entering the second complex don’t pump 4 protons across like complex one does].
Name some enzymes in mitochondria that can use the products of oxidative phosphorylation as a reactant
Enzymes in the mitochondria that can use it as a reactant are isocitrate dehydrogenase,
alpha-ketoglutarate dehydrogenase complex, and malate dehydrogenase.
Proton Motive Force:
provides energy to
drive ATP synthesis. ATP synthesis results from coupling proton flux to phosphorylation. Pumping out H+ generates an electrochemical gradient and the
energy is stored as a proton motive force.
Chemical energy potential – due to a H+ chemical gradient across the membrane,
and an electrical potential energy – due to a separation of charge (H+).
the Chemiosmotic Hypothesis
1. H+ are pumped to the intermembrane space using the electron transport chain
2. An electrochemical gradient is generated that serves as a proton motive force
3. H+ move down their gradient to generate the force for ATP synthesis