The Light-independent reaction

What products from the light dependent reaction are used in the light-independent reaction?

ATP

NADP

What products from the light dependent reaction used for?

Used to reduce glycerate 3-phosphate in the second stage of photosynthesis.

Where does the light independent reaction take place?

stroma of the chloroplasts.

Draw the Calvin cycle

Briefly describe the process of the light-independent reaction:

1. Carbon dioxide from the atmosphere diffuses into the leaf through the stomata, through the cell surface membrane, cytoplasm, chloroplast and into the stroma of the chloroplast.

2. In stroma, carbon dioxide reacts with the 5 carbon compound, ribulose biphosphate (RuBP). This reaction is catalysed by and enzyme called rubisco.

3. Reaction between CO2 and RuBP produces two molecules of the 3-carbon glycerate 3-phosphate (GP).

4. Reduced NADP from the light-dependent reaction is used to reduce glycerate 3-phosphate to triose phosphate (TP) using energy supplied by ATP.

5. NADP is reformed and goes back to the light-dependent reaction to be reduced again by accepting more protons.

6. Some triose phosphate molecules are concerted to organic substances.

7. Most triose phosphate molecules are used to regenerate ribulose biphosphate using ATP from the light-dependent reaction.

What are the useful organic compound triose phosphate molecules can be converted to?

• starch

• glucose

• cellulose

• amino acids

• nucleotides

How are chloroplasts adapted to carry out the light-independent reaction of photosynthesis? - 4

• The fluid of the stroma contains all the enzymes needed to carry out the light independent reaction.

• Membrane of the chloroplast separates the enzymes into a concentrated area from the outside area of the cytoplasm.

• Stroma fluid surrounds the grana, and so the products of the light-dependent reaction in the grana can readily diffuse into the stroma for the light-independent reaction.

• Contains both DNA and ribosomes so it can quickly and easily make the proteins involved in the light-independent reaction.