Evidence for chemiosmosis

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What is chemiosmosis?
Flow of hydrogen ions across a membrane which produces ATP.
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What is the chemiosmosis theory?
Build-up of hydrogen ions on one side of a membrane would be a source of potential energy and movement of ions across the membrane down an electrochemical gradient could provide energy needed to produce ATP from ADP and Pi.
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What is the inner mitochondrial membrane known as?
An energy-transducing membrane.
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What did Peter Mitchell suggest?
Energy released from transfer of electrons along the ETC was used to pump hydrogen ions from the matrix to the intermembrane space.
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Where did he say the protons went?
Protons flowed through protein channels attached to enzymes.
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What drove the formation of ATP?
The kinetic energy or the proton motive force.
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What has been found about some of the complexes in the electron transport chain?
Some have coenzymes that can use energy released from ETC to pump hydrogen ions across the membrane.
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How did some researchers treat isolated mitochondria?
Placed mitochondria in solutions of very low water potential so the outer membrane ruptured and released contents of intermembrane space.
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What could they do with further treatment?
They could rupture the inner membrane and release contents of the matrix.
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What did doing this allow them to do?
To identify where various enzymes are in the mitochondria and to work out that the link reaction and Krebd cycle take place in the matrix whilst electron transfer chain enzymes are embedded in the inner mitochondrial membrane.
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What did they conclude after electron transfer in mitochondria did not produce any ATP?
Concluded the intermembrane space was also involved.
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When was ATP not made?
Not made if mushroom-shaped parts of stalked particles were removed rfom the inner membrane of mitochondria or in the presence of oligomycin (an antibiotic) which blocked the flow of protons through the ion channel part.
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What was the potential difference across the inner membrane in intact mitochondria?
Potential difference was -200mV (more negative on matrix side than intermembrane space side).
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What was the pH of the intermembrane space?
pH of intermembrane space more negative than that of the matrix.
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Describe the 3 steps of ATP synthesis
The stalk rotates the head. ADP and Pi join to form ATP which is then released as the headpiece undergoes a shape change.
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Card 2

Front

What is the chemiosmosis theory?

Back

Build-up of hydrogen ions on one side of a membrane would be a source of potential energy and movement of ions across the membrane down an electrochemical gradient could provide energy needed to produce ATP from ADP and Pi.

Card 3

Front

What is the inner mitochondrial membrane known as?

Back

Preview of the front of card 3

Card 4

Front

What did Peter Mitchell suggest?

Back

Preview of the front of card 4

Card 5

Front

Where did he say the protons went?

Back

Preview of the front of card 5
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