Bioenergetics Flashcards
Life is complex and requires energy
Where does this energy come from? what is the vital spark?
Redox reactions. The
How is NADH transferred across the mitochondrial inner membrane?
NADH is transferred from the cytosol to the mitochondrial matrix via the malate-aspartate shuttle, a shuttle involving malate and glutamate.
Hence, to move NADH to the mitochondrial matrix we need to add glutamate and malate.
Special groups/cofactors involved in Respiration/Oxidation, electron transport
A key feature of electron transfer is redox centres. these often contain metal ions
Iron(Fe), copper (Cu) and Manganese (Mn)
Why are metal ions often associated with redox centers?
They have variable oxidation states. Hence they can accept/donate electrons
Cytochromes
These are heme-containing proteins that are involved in oxidation
The Fe ions in the heme undergo oxidation/reduction between Fe ++ and Fe ++
+
Most of the cytochromes are part of complexes, with the exception of cytochrome C, which is mobile
how many complexes are in the electron transport chain
4 complexes
The first step in the electron transport chain
Electrons pass from FADH or NADH enter into complex 1
Electron transport step 2
the electrons pass via coenzyme Q to complex 3
From complex 3 they pass via cytochrome C to complex 4
When do electrons enter into complex 2?
Electrons from the oxidation of succinate (FADH2) enter the chain at complex 2
What was a great insight into the chemiosmotic theory?
to understand how ucouplers work
Uncouplers
Agents that allow protons that form the electrochemical gradient to move back into the matric without gounf through ATP synthase
What is the result of uncouplers
It collapses the gradient, which means H+ pumping can occur without any back
pressure from the gradient
The protons are pumped out and return via the uncoupler pathway, Under these conditions electron flow through the electron transport chain increases but the free energy available is not linked to ATP production
What was the second major insight from the chemiosmotic theory?
Mitchell’s chemiosmotic theory emphasized the role of biological membranes as spatial organizers of reactions in cells.
