2. The Basic Facts
• It is the conversion of light energy
into chemical potential energy.
• The energy is stored in organic
molecules (e.g. ATP and glucose)
• Carbon dioxide is reduced to
produce carbohydrate
• So, it needs a supply of electrons
hydrogens and energy!

3. Chloroplast Structure
1. outer membrane 5. thylakoid lumen (inside of 9. starch
2. intermembrane space thylakoid) 10. ribosome
3. inner membrane (1+2+3: 6. thylakoid membrane 11. plastidial DNA
envelope) 7. granum (stack of thylakoids) 12. plastoglobule (drop of lipids)
4. stroma (aqueous fluid) 8. thylakoid (lamella)

4. Light dependent
stage
(on thylakoid
membranes)
• The aim is to produce a supply of
ATP (energy) and electrons that can
be used to reduce carbon dioxide.
• The electrons are carried by NADP
(called reduced NADP or NADPH
when it is carrying electrons).
• Oxygen is released as a waste
product.

5. Or put a different way…
NADPH
NADP
light
water dependent oxygen
reaction
ADP + P ATP

6. This is a blank slide for Mr King to do his own drawing on

7. Photolysis
• Using light energy to split water into
electrons, hydrogen ions and water.
• H2O H+ + e- + O2
• Replacing the electrons and hydrogen
ions now carried by NADPH

8. summary
• Chlorophyll absorbs light energy
and its electrons are ‘excited’
• ‘excited’ electrons pass through a
series of carriers releasing energy
to generate ATP from ADP and P
(photophosphorylation)
• Electrons are picked up by NADP
• Light energy splits water and the
electrons are used to replace
missing electrons in chlorophyll
• This all happens on membranes.

9. Light Independent stage
• Energy from ATP, hydrogens and
electrons from reduced NADP are
used to reduce carbon dioxide to
produce carbohydrate.
• This happens in the stroma.

10. Light independent stage
Reduced NADP
NADP
Carbon light
dioxide independent glucose
reaction
ATP ADP + Pi

11. (5C)
Ribulose Biphosphate
CO2
(1C)
ATP
2X Glycerate-3-Phosphate(3C)
NADPH ATP
(3C) 2X Triose Phosphate
Glucose (6C)

12. What happens without light?
• Which stages can
still continue when
the light is turned
off?
• Which molecules
will build up when
the light is turned
off?