ETC/ Oxidative phosphorylation Flashcards
What are the four major complexes in the ETC? What do they do?
Complex 1 - NADH dehydrogenase complex
catalyzes transfer of electrons from NADH to coenzyme Q
Complex 2- Succinate dehydrogenase complex
Catalyzes electron transfer from succinate to coenzyme Q
Complex 3 - Cytochrome bc1 complex
Transfer electrons from reduced coenzyme Q to cytochrome C
Complex 4- Cytochrome reducatse complex
Catalyzes transfer of 4 electrons to O2 to form H20
What type of enzymes are most of the enzymes in the ETC?
Oxidoreductases
What is UQ/Coenzyme 1?
UQ is lipid-soluble e- carrier that shuttles the e- between ETC complexes along
the inner mitochondrial membrane
What are cytochromes?
Proteins with heme groups attached. Addition of electrons changes oxidation state of heme iron.
What is the Q cycle?
Transfer of electrons through complex 3. For each 2 pairs of electrons transported, 2 cytochrome c are reduced.
What is cytochrome c?
Cytochrome c is a water-soluble mobile e- carrier of the outer face of the inner membrane
Which complex can be inhibited by ATP?
Complex 4
What is the energy released by NADH oxidation used for?
Pumping protons into intermembrane space to create proton gradient
How many molecules of ATP are produced per NADH? FADH2?
2.5 per NADH
1.5 per FADH2
`
What is the chemiosmotic coupling theory? What evidence exists in favor of it?
Explains how oxidative phosphorylation links ETC and ATP production
- Disruption of inner mitochondrial membrane stops respiration
- Disruption of proton gradient stops reproduction
Describe how ATP synthase works
Has 2 rotors linked by a stator
2 major components:
1) F1 = ATP synthase
2) F0 = Transmembrane channel - converts proton motive force into rotational force of the central shaft, which drives ATP synthesis
What are the subunits of ATP synthase? What are their functions?
3 alpha and 3 beta subunits
Beta subunits have the ADP and Pi binding sites
Beta subunits have 3 conformations
1) Loose - ADP and Pi bound
2) Tight- ATP bound
3) Open - ATP released, nothing bound
How is oxidative phosphorylation regulated?
Activated when ADP/Pi is high
Inhibited when ATP is high
Amounts of ATP and ADP in mitochondria are controlled by the ADP-ATP
translocator
Amount of H2PO4-is controlled by phosphate carrier (H2PO4- /H+ symporter)–aka phosphate translocase
What is the glycerol phosphate shuttle?
Mechanism to move NADH from cytoplasm to mitochondria
Cytoplasmic NADH reduces oxaloacetate to malate, which is transported to the matrix. Malate is then oxidized to yield NADH.
Which complex does not pump out protons?
Complex 2
