Topic 8 cellular respiration and photosynthesis
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Topic 8 – Cellular Respiration and Photosynthesis. 8.2 - Photosynthesis. Non-cyclic phosphorylation produces ATP. Chemiosmosis is the diffusion of ions across a selectively permeable membrane, through ATP synthase

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Topic 8 cellular respiration and photosynthesis

Non-cyclic phosphorylation produces ATP.

  • Chemiosmosis is the diffusion of ions across a selectively permeable membrane, through ATP synthase

  • The energy lost from the electrons moving down the electron transport chain drives chemiosmosis (similar to that in respiration) to bring about phosphorylation of ADP to produce ATP.

  • The enzyme NADP reductase catalyzes the transfer of the electron from ferredoxin to the energy carrier NADP+

Calvin cycle carbon fixation
Calvin Cycle – Carbon Fixation

RuBP binds to CO2 (carbon fixation)

- Fixation is catalyzed by RuBP carboxylase (rubisco)

- Result is an unstable 6-C compound

Calvin cycle reduction of glycerate 3 phosphate
Calvin Cycle – Reduction of glycerate 3-phosphate

ATP and NADPH act on G3P

- Forms two compounds of triose phosphate (TP)

- This is a reduction reaction

Calvin cycle final step s
Calvin Cycle – Final Step/s

  • Some molecule of TP leave the cycle while others become more complex carbohydrates

  • Most TP stay in the cycle to reproduce RuBP

  • To regain RuBP from TP, the cycle uses ATP

Light dependent vs light independent reactions
Light-dependent vs Light-independentreactions



Occurs in the stroma

Uses ATP and NADPH to form triose phosphate

Returns ADP, inorganic phosphate and NADP to the light-dependent reaction

Involves the Calvin cycle

  • Occurs in thylakoids

  • Uses light energy to form ATP and NADPH

  • Splits water in photolysis to provide replacement electrons and H+ and to release oxygen to the atmosphere

  • Includes two electron transport chains and photosystems I/II

The chloroplast and photosynthesis
The chloroplast and photosynthesis

Chloroplast structure

Function allowed

Allows greater absorption of light by photosystems

Allows faster accumulation of protons to create a concentration gradient

Allows an area for the enzymes necessary for the Calvin cycle to work

Isolates the working parts and enzymes of the chloroplast from the surrounding cytosol

  • Extensive membrane surface area of the thylakoids

  • Small space (lumen) within the thylakoids

  • Stroma region similar to the cytosol of the cell

  • Double membrane on the outside