oxidative phosphorylation and chemiosmosis Flashcards
What is oxidative phosphorylation
The format italy of ATP by adding a phosphate group to ADP
In the presence of oxygen which is the final proton acceptor
Intro to the finals Tages of aerobic respiration
Involves electron carriers embedded in the inner mitochondrial membranes
These membranes are folded into cristae, increasing the surface area for electron carriers and ATP synthase enzymes
Reduced nad and reduced fad recipient when they donate hydrogen atoms which are split into protons and electrons, to the electron carriers
The first electron carrier to accept electrons from reduced nad is a protein complex, complex 1 called NADH - coenzyme q reductase (aka NADH dehydrogenase)
The protons go into solution in the matrix
Where do the electrons go when split from hydrogen atoms
Electrons carrier accepts them
First one to accept from reduced nad would be NADH dehydrogenase
Where do protons go when split from hydrogen atom
Go into solution in the matrix
Talk about the electron transport chain
The electrons are passed along a chain of electron carriers and then donated to molecular oxygen, the final electron acceptor
What is the final electron acceptor that electrons are donated to in the electron transport chain
Oxygen
Tall about chemiosmosis
As electrons flow through the electron transport chain energy is release and used by coenzymes associated with some of the electron carriers, this is to pump the protons across the intermermembrane space
This builds up a proton gradient which is also a pH gradient and an electrochemical gradient
Thus potential energy builds up in the interment range space
The hydrogen ions/protons can’t diffuse through the lipid part of the inner membrane but can diffuse through ion channels in it. These channels are associated with the enzyme ATP synthase. This flow of hydrogen ions/ protons is chemiosmosis
What creates a proton gradient or pH or electrochemical gradient
Electrons flowing through electron transport chain
Protons being pumped across the intermembrane space
Why does potential energy build up in the intermembrane space
Cz proton gradient builds up
Talk about oxidative phosphorylation
As protons flow through an ATP synthase enzyme, they drive the rotations of part of the enzyme and join ADP and an inorganic phosphate to form ATP
Electrons are passed from the last electron carrier in the chain to molecular oxygen, the final electron acceptor
Hydrogen ions then join so that oxygen is reduced to water
Equation in book
How do hydrogen ions or protons go to intermembrane space
Can’t diffuse through lipid part of inner membrane but can diffuse through ion channels in it
The channels are associated with the enzyme ATP synthase. This flow of hydrogen ions or p tons is chemiosmosis
How much ATP is made before oxidative phosphorylation
For each glucose molecule
2 molecule of ATP have been gained during glycolysis by substrate level phosphorylation
2 molecules of ATP have been gained during Krebs cycle by substrate level phosphorylation
How much ATP is made during oxidative phosphorylation
More ATP made
Reduced nad and fas molecules are re oxidised
Reduced nad and reduced fad will both provide electrons to the electron transport chain to be used in oxidative phosphorylation
Reduced nad also provides hydrogen ions or protons that contribute to the build up of the proton gradient for chemiosmosis. The hydrogens from reduced fad stay in the matrix but can combine with oxygen to form water
10 molecules of reduced nad can theoretically make 26 molecules of ATP during oxidative phosphorylation
So for each receded nad molecules. That is reoxidised up to 2.6 molecules of ATP should be made
Together. With the ATP made during glycolysis and Krebs cycle the total yield of ATP molecules should be 30
Number if molecules made from one molecule of glucose
Reduced nad in glycolysis link and Krebs
2
2
6
Reduced fad in glycolysis link and Krebs
0
0
2
Why is total yield not always 30 ATP molecules?
Some protons leak across the mitochondrial membrane, reducing the number of protons ti generate the proton motive force which builds up por et ni tial energy in the intermembrane space
So protons can’t be pumped into the intermembrane space and can’t diffuse through ion channels. So si ATP synthase enzyme won’t rotate and ATP won’t be made
Some ATP produced is used to actively transport pyruvate into the mitochondria
Some ATP is used for the shuttle to bring hydrogen from reduced nad made during glycolysis in the cytoplasm into the mitochondria
