Metabolism
How many photons are required for one electron?
- For each electron one photon.
How many electrons required for one NADPH?
- 2 electrons
For regeneration in the Calvin cycle you need 3 ATP and no NADPH, for carboxylation you
need neither ATP nor NADPH, for the reduction you need 6 ATP and 6 NADPH. In total this
makes 9 ATP and 6 NADPH needed for the net gain of 3 Carbon.
How many protons have to move from the stroma to the lumen to generate 1 molecule of
ATP?
- If the rotor contains 10 subunits it is → 10/3 = 3,3, but if the rotor contains 15
subunits it is → 15/3 = 5
How many photons are required to hit PSI to generate enough NADPH molecules for the
production of 1 sucrose molecule?
- 1 sucrose molecule needs 4 cycles and in each cycle you need 6 NADPH
4 x 6 = 24 NADPH required.
2 electrons are required for every NADPH, therefore 48 electrons are required, this
equals with 48 photons.
How many photons are required to hit PSII to generate enough ATP molecules for the
production of 1 sucrose molecule?
- 1 sucrose molecule needs 4 cycles, one cycle makes 9 atp
4 x 9 = 36 atp required.
3,33 protons required for 1 ATP
36 x 3,33 = 120 protons required in lumen
Each 2 electrons (=2 photons) : 4 protons in lumen (2 fom water and 2 via plastoquinone)
120 protons : 60 electrons equals 60 photons.
Does this result in enough electrons to donate to PSI to compensate the electrons required
for NADPH production?
- More than enough, you need 48 but have 60 electrons.
How many oxygen molecules are produced during this process?
- Oxygen molecules : 60 electrons equal 30 water molecules equals 15 oxygen
molecules that are produced.
NB PSI is almost 100% efficient , while PSII is only 80% efficiënt (80% of absorbed photons
result in charge separation.) 80% of 60 electrons is exactly 48.
Which 4 protein complexes (termed 1-4 in the figure below) in the thylakoid membrane work
together to form the ATP and NADPH required for the Calvin cycle?
- 1) PSII 2) cytochrome 3) PSI 4) ATP synthase.
, What are the names of the two mobile membrane proteins that carry electrons between 1
and 2, and between 2 and 3?
- A is plastoquinone en B is plastocyanin
What is the advantage of the CAM mechanism in the photosynthesis for plants growing in
drought stress?
- The stomata is closed during the day so they don't evaporate water also, separation
of CO2 fixation, storage of oxalic acid in vacuole and carbon cycle during the day.
In which stage of the calvin cycle (CO2 assimilation) is 3-phosphoglycerate (3PGA)
produced?
- In the carboxylation stage
Where and how does the movement of water take place in plants ?
→ In the xylem and it happens because of apoplastic and symplastic movement.
The Calvin cycle in C4 plants takes place in the bundle sheath cells.
Oxaloacetate is produced in C4 plants by carboxylation and catalysed by PEP carboxylase
(PEPC).
How many photons are required for one electron?
- For each electron one photon.
How many electrons required for one NADPH?
- 2 electrons
For regeneration in the Calvin cycle you need 3 ATP and no NADPH, for carboxylation you
need neither ATP nor NADPH, for the reduction you need 6 ATP and 6 NADPH. In total this
makes 9 ATP and 6 NADPH needed for the net gain of 3 Carbon.
How many protons have to move from the stroma to the lumen to generate 1 molecule of
ATP?
- If the rotor contains 10 subunits it is → 10/3 = 3,3, but if the rotor contains 15
subunits it is → 15/3 = 5
How many photons are required to hit PSI to generate enough NADPH molecules for the
production of 1 sucrose molecule?
- 1 sucrose molecule needs 4 cycles and in each cycle you need 6 NADPH
4 x 6 = 24 NADPH required.
2 electrons are required for every NADPH, therefore 48 electrons are required, this
equals with 48 photons.
How many photons are required to hit PSII to generate enough ATP molecules for the
production of 1 sucrose molecule?
- 1 sucrose molecule needs 4 cycles, one cycle makes 9 atp
4 x 9 = 36 atp required.
3,33 protons required for 1 ATP
36 x 3,33 = 120 protons required in lumen
Each 2 electrons (=2 photons) : 4 protons in lumen (2 fom water and 2 via plastoquinone)
120 protons : 60 electrons equals 60 photons.
Does this result in enough electrons to donate to PSI to compensate the electrons required
for NADPH production?
- More than enough, you need 48 but have 60 electrons.
How many oxygen molecules are produced during this process?
- Oxygen molecules : 60 electrons equal 30 water molecules equals 15 oxygen
molecules that are produced.
NB PSI is almost 100% efficient , while PSII is only 80% efficiënt (80% of absorbed photons
result in charge separation.) 80% of 60 electrons is exactly 48.
Which 4 protein complexes (termed 1-4 in the figure below) in the thylakoid membrane work
together to form the ATP and NADPH required for the Calvin cycle?
- 1) PSII 2) cytochrome 3) PSI 4) ATP synthase.
, What are the names of the two mobile membrane proteins that carry electrons between 1
and 2, and between 2 and 3?
- A is plastoquinone en B is plastocyanin
What is the advantage of the CAM mechanism in the photosynthesis for plants growing in
drought stress?
- The stomata is closed during the day so they don't evaporate water also, separation
of CO2 fixation, storage of oxalic acid in vacuole and carbon cycle during the day.
In which stage of the calvin cycle (CO2 assimilation) is 3-phosphoglycerate (3PGA)
produced?
- In the carboxylation stage
Where and how does the movement of water take place in plants ?
→ In the xylem and it happens because of apoplastic and symplastic movement.
The Calvin cycle in C4 plants takes place in the bundle sheath cells.
Oxaloacetate is produced in C4 plants by carboxylation and catalysed by PEP carboxylase
(PEPC).
