Light Independent Reaction - Calvin Cycle Flashcards
(19 cards)
What is photoionisation?
The excitation of 2 electrons from chlorophyll (PSII)
What is the Calvin cycle?
A series of reactions that produce the organic compounds that a plant need including glucose
What does the Calvin cycle need?
ATP and NADPH
When will the Calvin cycle have to stop?
In abscence of NADPH and ATP (if they aren’t replaced
Where does the Calvin cycle happen?
In the stroma of the chloroplasts
What are the 3 main parts of the Calvin cycle?
1) Carbon fixation
2) Reduction
3) Regeneration
What happens in carbon fixation?
The enzyme RUBISCO catalyses the reaction of ribulose biphosphate (RuBP) and carbon dioxide into TWO glycerate-3-phosphates (GP)
What happens in reduction?
Reduced NADP (NADPH) from the LDR reduces GP into TWO triose phosphate using energy from ATP
What happens in regeneration?
-Some triose phosphate is converted in useful organic compounds e.g. glucose
-Some is regenerated back into ribulose biphosphate using energy from ATP to maintain its supply
Explain how CO2 is converted into organic substances in the light independent reaction of photosynthesis exam q
1) Carbon dioxide combines with ribulose biphosphate
2) Produces TWO glycerate 3-phosphate
3) GP reduced to triose phosphate
4) This happens using reduced NADP
5) Using energy from ATP
6) Triose phosphate is converted to glucose
What are hexose sugars?
Simple 6-carbon sugars e.g. glucose
How is 1 hexose sugar made?
By joining two molecules of triose phosphate together
How many times does the Calvin cycle need to turn to make 1 hexose sugar? And why
6 times
—> 3 turns make 6 molecules of triose phosphate
—> 5 out of 6 of these TP molecules are used to regenerate RuBP
—> So for 3 turns of the cycle, only one TP is produced that’s used to make a hexose sugar
—> Hexose has 6 carbons so 2 TP molecules are needed
What are triose phosphate and glycerate 3-phosphate molecules used to make?
-Carbohydrates
-Lipids
-Amino acids
What are lipids made from?
Using glycerol
—> synthesised from triose phosphate, and fatty acids which are synthesised from glycerate 3-phosphate
What are some amino acids made from?
Glycerate 3-phosphate
Label this Calvin cycle
Well doneee 🌹🌹
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