Mitochondria Flashcards
Exaggerated increase in ATP level that would
inhibit respiration
What can prevent an exaggerated increase in ATP level?
partial uncoupling of respiration
Uncoupling proteins (UCPs) are ?
Found in which cell?
Present in ?
- Mitochondrial transporters present in the inner membrane of mitochondria.
- Found in all mammals and in plants.
- Present in mitochondria of brown adipocytes (fat cells), the thermogenic cells that maintain body temperature.
Uncoupling dissipates energy of ———- ———– as —-
substrate oxidation as heat
Uncoupling allows __________ _______ of _______ that are essential to metabolic pathways.
continuous reoxidation of coenzymes
Electron leakage can occur to form _____ which link to ______ & _________
form oxygen free radicals (linked to ageing & cancer)
( Respiration - ATP / Mitochondria membrane)
For Heat generation?
For Energy conservation?
For Heat generation- uncoupled / Proto leaky
For Energy conservation- well coupled / Proto non- leaky
Bacteria make ATP during respiration by
pumping protons outwards and allowing the protons to re-enter the cell via an ATP synthase – just like mitochondria
mitochondria (size)
Large organelles, easily visible using light microscopes
Usually depicted as cylinders around 0.5 – 1 mm in diameter and up to 7 mm long, but actually are remarkably plastic and can change shape and move around the cell.
They can even fuse with one another and then move apart again.
mitochondria (no of cell)
The number of mitochondria per cell varies according to the energy requirements of the cell.
Average cell: 200
Liver cell: 1000-2000 mitochondria (20% of the total cell volume)
Skeletal muscle: 4000 (in athletes)
Some cells (e.g. fat cells, skin cells) only have a few mitochondria
mitochondria (structure)
Two highly specialised membranes (inner and outer) that creates an intermembrane space and the internal matrix.
mitochondria (inner membrane structure/ function)
The inner membrane is a highly specialised lipid bilayer that is particularly impermeable to ions and is the site of the electron transport chain and ATP synthesis.
The inner membrane is also highly convoluted, forming folds called cristae
cristae
highly convoluted folds formed by the inner membrane projecting into the matrix and serve to greatly increase the surface area of the inner membrane.
mitochondria (matrix function)
The matrix contains enzymes that metabolise pyruvate and fatty acids to produce acetyl CoA and also enzymes that oxidise acetyl CoA in the citric acid cycle
Reduction /Oxidation ?
Exammple
Reduction is the addition of an electron e-
Oxidation is the removal of an electron e-
H = e- + H+
FAD + 2H -> FADH2
NAD+ + 2H NADH + H+
NAD+ + 2 e- + 2H+ NADH + H+
NAD+ + 2 e- + 2H+ NAD+(2 e-+H+) + H+
[Electrons reduce / Protons (H+) neither reduce nor oxidise]
1 molecule of glucose yields a net production of______
Under aerobic conditions, it can yield _______
1 molecule of glucose yields a net production of 2 ATP molecules.
Under aerobic conditions this can increase to 4 ATP molecules.
Glucose can be metabolised through _____to produce energy
The reactions occur at ________
Glucose can be metabolised through oxidation to produce energy (glycolysis).
These reactions occur in the cytosol.
The citric acid cycle occurs in ?
and produced _________ for _________
in the mitochondrial matrix and produces reduced electron carriers (e.g. NADH or FADH2) for the electron transport chain.
At the electron transport chain, Electrons are passed through _________ to ________
Electrons are transferred from NADH or FADH2 to pass through a number of proteins including cytochromes (each with an iron atom) to O2
the electron transport chain’s function
to break the large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts.
Transfer of electrons from NADH to O2 occurs at
occurs through three large respiratory enzyme complexes (multiprotein complex) located in the inner mitochondrial membrane, in the cristae.
At the electron transport chain, electrons drop in _______ to _____, forming _____
drop in free energy as they go down the chain and are finally passed to O2, forming H2O
The three respiratory enzyme complexes
- NADH dehyfrogenase complex - Largest complex, > 40 polypeptide chains
- Cytochrome b-c(1) complex - 11 polypeptide chains, Functions as a dimer
- Cytochrome oxidase complex - 13 polypeptide chains
The cytochrome oxidase complex accounts for
around 90% of the total oxygen uptake in most cells.
