This has been the 1463rd visit to this site since Oct. 11, 1996.

Word roots:

ana (G) = up, again, as in anabolism
cat (G) = down, downward, as in catabolism
chlor (G) = Green
cycl (G) = A circle, wheel
lact (L) = milk
sys, sym or syn (G) = with, together, as in symbiosis, system, synthesis

OVERVIEW OF PHOTOSYNTHESIS

ATP and reducing power from Light Reaction used to reduce CO2 during Calvin Cycle.

LIGHT REACTION

Photosynthetic pigments absorb light at different wavelengths. Fig. 10.6 (why leaves are green)
Pigment molecules occur in bunches called PHOTOSYSTEMS where energy can be passed to the Reaction Center which is a Chlorophyll a molecule.

(Fig. 10.10)

OXIDATION of Chlorophyll occurs when one of its e- gets energized by this energy.
What happens to the e-?

FIG. 10.9 (not spatially correct: height = energy level)

NONCYCLIC e- flow. (photosystem I and II)
H2O is split to provide e-
2 Photosystems involved
e- end up on NADPH

See FIG. 10.11
NADPH, O2 and ATP produced

ATP production is via chemiosmosis
see Figs. 10.14 and 10.15 for spatial arrangement of photosystems and ATP synthase.

CYCLIC electron flow. (photosystem I)
e- are cycled back to reaction center and ATP (but no NADPH or O2) is produced.
See FIG. 10.13

The ATP and NADPH produced by the light reaction are used to synthesize sugars from CO2 via the Calvin Cycle

Occurs in the Stroma - Refer back to Fig. 10.15 and 10.4.

Fig. 10.16

It is a reductive cycle, taking CO2 and reducing it to Sugar.

Go through some steps

Step 1. 5 + 1 = 6 ---> 2 x 3 (enzyme = RuBP carboxylase)

Step 2. phosphorylation (uses up some of the ATP from the light rxns).

Step 3. reduction (glyceraldehyde phosphate same as in glycolysis)

Wrap up Photosynthesis with Fig. 10.19