What happens to the chloropyll molecule when it absorbs light energy?
A couple of electrons become excited and are rasied to higher energy levels until they leave the molecule, ionising it
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What is this process called?
Photoionisation
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What takes up the electrons that have left the chlorophyll molecule?
An electron carrier
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What has happened to the chlorophyll molecule if it has lost a pair of electrons?
It is oxidised
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As the electron carrier has gained electrons what has happened to it?
It has been reduced
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Where is the electron carrier that has taken up the chlorophyll molecule electrons?
In the thylakoid membrane
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Where do the electrons travel next?
They travel along a transfer chain of electron carriers
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What types of reactions take place down the transfer chain of electron carriers?
Redox reactions
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Why do electrons lose energy at each stage of the transfer chain?
Each new electron carrier is at a lower energy level than the last
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What is the theory called that explains the precise mechanism of producing ATP?
Chemiosmotic theory
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What are pumped from the stroma into the thylakoid space in the chemiosmotic theory?
H+ ions
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What pump the H+ ions into the stroma?
Protein carriers called proton pumps
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Where are the proton pumps?
In the thylakoid membrane
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Where does the energy to drive this process come from?
From the energy that the electrons released travelling down the electron transfer chain
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What is the equation for the photolysis of water?
2H2O --> 4H+ + 4e- + O2
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How does the proton pump help with producing ATP?
It creates a higher concentration of H+ ions in the thylakoid space hence a steep concentration gradient
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How do the protons get into the stroma down their concentration gradient?
Through an ATP synthase channel
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How do the H+ ions help produce ATP when travelling through the ATP synthase channel?
It cause changes to the structure of the enzyme which then catalyses the combination of ADP with Pi to form ATP
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Once the H+ ions have passed through the ATP synthase channel where do they go?
They are taken up by an electron carrier called NADP
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What happens to the NADP when it takes up these protons?
It becomes reduced NADP
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What happens to the electrons produced during photolysis?
They replace the electrons lost from the chlorophyll molecule
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What happens to the oxygen produced during photolysis?
It either diffuses out of the leaf as a waste product or it is used for respiration
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How are the thylakoid membranes adapted to photosynthesis?
- They provide a large surface area for the attachment of chlorophyll, electron carriers and enzymes - They're semi-permeable to H+ ions which allow a concentration gradient
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What holds the chrorphyll in a position for maximum light absorbance?
A network of proteins in the grana
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Why do chloroplasts contain DNA and ribosomes?
So they can quickly synthesise proteins needed in the light-dependent reaction
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What are the three products of the light-dependent stage?
- ATP - Reduced NADP - Oxygen
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Other cards in this set
Card 2
Front
What is this process called?
Back
Photoionisation
Card 3
Front
What takes up the electrons that have left the chlorophyll molecule?
Back
Card 4
Front
What has happened to the chlorophyll molecule if it has lost a pair of electrons?
Back
Card 5
Front
As the electron carrier has gained electrons what has happened to it?
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