1. The details behind anabolic cellular energetics
Photosynthesis
The details behind anabolic cellular energetics

2. Photosynthesis—chloroplasts
Chloroplast structure
Function allowed
Large membrane surface area of the thylakoids
Greater absorption of light
Small space (lumen) within the thylakoids
Faster accumulation of protons
Stroma region similar to the cytosol of the cell
Area for the enzymes necessary for the Calvin cycle to work
Double membrane on the outside
Isolates the working parts and enzymes from the cytosol
All photosynthetic processes take place within the chloroplast (unlike respiration & mitochondria)
Membrane-bound organelle with evidence of endosymbiosis
own membrane, own DNA, large size
Found mostly in leaves, but can be found in other plant organs

3. Photosynthesis—light dependent
Excited electron acceptor e-
Electron carrier (PQ)
cytochrome complex
(electron carrier)
Energy of electrons
Electron carrier H+
Photosystem II
Photosystem I

4. Photosynthesis—light dependent
cytochrome complex
(electron carrier)
Photosystem II
Excited electron acceptor e-
Electron carrier (PQ) H+
Electron carrier
Energy of electrons
Photosystem I

5. Photosynthesis—light dependent
Excited electron acceptor e-
Ferredoxin (electron carrier)
NADP
Reductase
Energy of electrons
NADP+ + H+
NADPH
Photosystem I

6. Photosynthesis—light dependent
Final electron acceptor is NADPH

7. Photosynthesis—light dependent
Electrons replaced via photolysis of water
Only known system in nature where oxygen is oxidized
As energy level of electrons falls, H+ pumped into thylakoid space, creates gradient
Chemiosmosis results in H+ coming through ATP synthase, generating ATP in stroma
Photophosphorylation
The energy that is used to add a phosphate to ADP to create ATP comes from the sun

8. Photosynthesis—light dependent
Respiration chemiosmosis
Photosynthesis chemiosmosis
ETC chain embedded in the membrane of the cristae
ETC embedded in the membranes of the thylakoids
Energy released when e- are exchanged from one carrier to another
Same!
Released energy used to pump H+ ions into the intermembrane space
Released energy used to actively pump H+ ions into the thylakoid space
H+ ions come from the matrix
H+ ions come from the stroma
H+ ions diffuse back into the matrix through ATP synthase
H+ ions diffuse back into the stroma through ATP synthase
ATP synthase catalyses the oxidative phosphorylation of ADP to form ATP

9. Photosynthesis—light independent
NADPH and the ATP generated in the light dependent reactions needed to drive this process
CO2 fixed (integrated into a non-gaseous molecule) into glucose
Occurs in the stroma

10. Photosynthesis— light independent
GP - Glycerate
3-Phosphate
TP – triose phosphate (Glyceraldehyde phosphate)
A total of 12 ATP and 12 NADPH molecules needed for ONE glucose molecule
TP, first molecule made in glycolysis
(these are reverse rxns)
RUBSICO—a lot of it b/c not very efficient & it’s a part of a VERY important process— carbon fixation
RUBISCO

11. Photosynthesis—rates
Three main factors you need to know that affect photosynthetic rates:
Light intensity
CO2 concentration
Temperature
Be able to explain the different aspect of each graph in terms of why it looks the way it does
Also be able to draw the graphs on your own

12. Photosynthesis—rates
Distance from light source and power can affect the light intensity

13. Photosynthesis—rates
Optimum temperature
As temperature increases, enzyme rates increase until the point of denaturation

14. Photosynthesis—rates
CO2 saturation for most plants
carbon dioxide/ppm in atmosphere
Only so much RuBP to react with (and other limitations)

15. Photosynthesis—cyclic vs non-cyclic photophosphorylation

16. Photosynthesis—cyclic vs non-cyclic photophosphorylation
OFF TO THE CALVIN CYCLE e– e–
NON-cyclic photophosphorylation
Where do the replacement electrons come from?
Photolysis of H2O
There is a cyclic photophosphorylation too
ATP produced, NO NADPH sent to Calvin cycle H+
H2O e—
½ O2 H+ e—

17. Photosynthesis—cyclic vs non-cyclic photophosphorylation

18. Photosynthesis—cyclic vs non-cyclic photophosphorylation
e_ gets recycled: continually providing energy to establish H+ gradient
Occurs when light is not a limiting factor + NADPH levels are high in the chloroplasts
Extra ATPs produced head to Calvin cycle allowing it to occur more rapidly