The Mitochondrion
Complex 1, NADH Dehydrogenase (ETC)
- 20 subunit proteins, believed to be L shaped - the flavin nucleotide (FMN) recieves a pair of electrons from NADH, NADH releases it's H+ into the matrix. FMS passes the electrons one at a time through a series of FeS groups to a molecule of CoQ held in a bonding pocket near the matrix side of the complex. - the movement of electrons through the complex releases energy that alters the structure of the complex, this allows the H+ to pump from the matrix to the intermembrane space.
The Outer Membrane
- a smooth boundary for the mitochondrion, known for the high content of the protein 'mitochondrial porin', forms a beta barrel, a large pore
Complex 2, Succinate Dehydrogenase
- a succinate is oxidized its electrons and H+ are transferred to the FAD creating FADH2, releases the H+ into the matrix and passes electrons via FeS groups to CoQ.
The Intermembrane Space
- between the inner and outer membrane, the contents roughly match the cytosol. There are few proteins, the primary one being the cytochrome-c
Complex 4, cytochrome oxidase
- electrons moving from 3 to 4 are passed one at a time to cytochrome-c, this small protein is a mobile electron carrier, trapped inside the inner and outer membranes. - complex 4 is made up of 13 protein subunits, 2 of which are crucial to its electron transport function 1. binding molecular oxygen 2. transferring e- to the oxygen creating reative oxygen species 3. absorbing h+ from the matrix, uniting w/reactive oxygen to form water 4. using energy released in the process to pump 2H+ from the matrix to the inter membrane space, for every pair of electrons
ETC
- recieves 'high energy' electrons from the oxidative reactions of catabolism and passes them along with H+, to molecular oxygen forming water. These steps are coupled to the generation of an electrochemical, energy storing, gradient that is subsequently used to produce ATP.
Mitochondrial Matrix
- the central 'fluid' compartment of the mitochondrion, densely packed with protein and particles. -Enzymes and metabolites of the cirtic acid cycle, and beta oxidation cycle live here. -DNA ribosomes that make the mitochondrion a semi-autonomous reside here.
Proton Motive Force
- the electrochemical gradient for H+ from the movement of H+ from the matrix to the intermembrane space decreases its concentration in the matrix and the charged intermembrane space becomes more positive. This starts and electrical gradient, represents stored or potential energy.
Mitochondrion
- the energy power plants of the cell - mitochondrion can fuse, producing extensive branched networks, and also undergo fission back to individual units.
Complex 3
- the energy released in this process is sufficient to allow CoQ to 'shuttle' 4H+ from the matrix to the intermembrane space for every pair of electrons transported along the chain.
The Inner Membrane (characteristics)
1. Folded into cristae to increase surface area. 2. not smooth, has a large number of projections 3. Unusual lipid composition, impermeable to H+ 4. High protein content, diverse transporters, electron carriers, and enzymatic proteins. 5. 'Inner boundary membrane'- helps define intermembrane space, rich in metabolite transporters and protein translocators 6. 'cristae Paper'- rich in ETC components, and ATP- synthase.
ATP Synthase (Identification)
the hypothesis of Mitchell proposed that the H+ ion gradient was the driving force behind ATP synthesis. This observation came from the observation that dislodging the particle stopped ATP synthesis.
