Mitochondria Flashcards
Outer mitochondrial membrane structure and permeability
- contains porins which act as channel proteins
- permeable to proteins 5kDa or less
Mitochondrial inter-membrane space composition & pH
- similar to cytoplasm
- higher protein composition than matrix
- lower pH than matrix
Mitochondrial matrix composition & pH
- viscous containing less water than cytoplasm
- contains DNA, ribosomes, enzymes, organic molecules & inorganic ions
- pH more alkaline than IMS
Enzymes in mitochondrial matrix enable reactions like:
TCA cycle
beta-oxidation
oxidative phosphorylation
Inner mitochondrial membrane (Cristae) structure and permeability
- extensively folded
- freely permeable to O2, CO2 and H2O
- less permeable to ions and small molecules than outer membrane
Where are mitochondria found?
near sites of high ATP use
Mitochondria often fuse to make:
elongated tubular networks which can extend throughout cytoplasm
Mitochondrial origins
Endosymbiotic theory
Mitochondrial DNA
- circular
- extra-genomic to cells they’re found in
Mitochondrial functions (6)
- TCA cycle
- beta-oxidation
- oxidative phosphorylation
- chemiosmosis
- cyt c release for apoptosis
- calcium ion regulation
Synthetic uncouplers disrupt:
oxidative phosphorylation
Synthetic uncouplers act by:
binding to H+ which uncouples pH gradient from ATP synthesis causing ATP depletion and energy generated by e- transfer is lost as heat
Thermogenin
- uncoupling protein found in brown adipose tissue of newborn mammals
- acts as proton channel increasing H+ permeability allowing them back into matrix without passing through ATP synthase which means energy is used to generate heat
Mitochondrial involvement in apoptosis:
- cytochrome c released into cytosol from mitochondrial IMS
- cyt c binds to adaptor protein and assembles into 7-armed complex which becomes an apoptosome
Mitochondrial diseases
can occur in any organ & have many different outcomes
