Terminal Respiration Flashcards
Describe the basic definition of terminal respiration
Terminal respiration is when reduced co-reactants can pass on their high energy electrons (that eventually combine with O2 to form H2O) through a series of carrier proteins to yield lots of ATP.
Describe the requirements of NADH and FADH2 for oxidation in terminal respiratory system.
NADH and FADH2 have to be in the mitochondrial matrix, the majority of the NADH and FADH2 is already in the mitochondrial matrix (i.e. that of the TCA cycle and B oxidation), but some is in cytoplasm (glycolysis).
But NADH and FADH2 cannot cross the membrane so are transported into the matrix by shuttle systems.
Describe the glycerol phosphate shuttle.
Found in brown adipose tissue.
Catalysed by glycerol - 3 - phosphate dehydrogenase.
G-3-P, passes its electrons to FADH2, the oxidation of FADH generates less ATP than NADH, so energetic price.
Describe complex 1 of the electron transport chain.
Oxidises NADH, passes electrons to ubiquinone to give ubiquinol (QH2).
Pumps proteins (H+ ions into intermembrane space).
Describe complex 2 of the electron transport chain.
This involves the entry of FADH2.
Which is oxidised once in the cell.
Also passes electrons to ubiquinone to make ubiquinol (QH2).
Utilises Fe-S centres to channel electrons.
The heme group of this molecule, blocks stray electrons, which are free radicals if they leak.
Describe complex 3 of the electron transport chain.
Nme: Q - cytochrome c oxidoreductase.
This takes electrons from ubiquinol and passes them to cytochrome c.
1 ubiquinone is oxidised to yield 2 reduced cytochrome c molecules.
This complex is responsible for pumping protons into intermembrane space.
Describe complex 4 of the electron transport chain.
Name: cytochrome c oxidase.
The only place in energy metabolism where O2 is involved.
This complex takes electrons from cytochrome c and passes them to molecular oxygen. The electrons are channelled through Fe-Cu centre. Pumps protonx into intermembrane space.
Describe the energy conversion in the electron transport chain.
The energy conserved leads to oxidation of NADH, FADH2, ubiquinone and cytochrome c.
The energy is further conserved through setting up of protein gradient.
Describe the creation of the protein gradient across the mitochondrial membranes.
The outside of the cell has a higher conc. of proteins and so is more positively charged.
The inside is negatively charged.
While the electrons move through the complexes in the electron transport chain, protons from the matrix move to the intermembrane space.
Explain how energy is stored in the H+ gradient.
There is a pH difference between the matrix and intermembrane space of the mitochondria. (matrix is alkaline).
The difference in charge created an electromotive force which allows the protein gradient to do the work.
ATP synthase, which is a molecular turbine that harnesses the energy in the protein gradient.
Describe the two regions of the ATP synthase.
F,0 - This is essentially a membrane bound proton conducting unit, it consists of 10 subunits and is the anchorage into the membrane.
F,1 - A large globular protein that protrudes into the matrix.
(it acts as a catalyst for ATP synthesis)
Describe the cooperating structure and functions of the ATP synthase.
ATP synthase rotates (like a turbine).
The central gamma region (F,0) is the rotating part and the surrounding Beta (F,1 units) change conformation and are driven by the proton gradient to allow the addition of ADP and Pi to release ATP.
Release not formation.
Describe the binding change mechanism.
Sequential conformational changes of Beta subunit.
There are 3 different binding pockets and therefore 3 different states.
Tight, open and loose binding pockets.
State the number of moles of ATP produced from NADH and FADH2.
FADH2 - 1.5 (2) mol
NADH - 2.5 (3) mol
Describe the reaction coupling involved in terminal respiration.
The electron transport chain is said to be coupled to ATP synthase.
