Atlantic Ocean in Winter Fig. 6-1a p.92

Fig. 6-2, p.94

Fig. 6-3, p.95

p.97

upper epidermis photosynthetic cells leaf vein lower epidermis a Zooming in on a photosynthetic cell. lower epidermis Fig. 6-6a, p.97

two outer membranes of chloroplasts stroma part of thylakoid membrane system bathed in stroma: thylakoid compartment, cutaway view b Chloroplast structure. No matter how highly folded, its thylakoid membrane system forms a single, continuous compartment in the stroma. Fig. 6-6b, p.97

c In chloroplasts, ATP and NADPH form in the light-dependent stage of sunlight O2 H2O CO2 CHLOROPLAST NADPH, ATP light- dependent reactions light- independent reactions NADP+, ADP sugars CYTOPLASM c In chloroplasts, ATP and NADPH form in the light-dependent stage of photosynthesis, which occurs at the thylakoid membrane. The second stage, which produces sugars and other carbohydrates, proceeds in the stroma. Fig. 6-6c, p.97

electron transfer chain light energy light energy electron transfer chain NADPH Photosystem II Photosystem I THYLAKOID COMPARTMENT THYLAKOID MEMBRANE oxygen (diffuses away) STROMA Fig. 6-8b, p.99

a CO2 in air spaces inside a leaf diffuses into a photosynthetic cell. Six times, rubisco attaches a carbon atom from CO2 to the RuBP that is the starting compound for the Calvin–Benson cycle. f It takes six turns of the Calvin–Benson cycle (six carbon atoms) to produce one glucose molecule and regenerate six RuBP. 6CO2 b Each PGA molecule gets a phosphate group from ATP, plus hydrogen and electrons from NADPH. The resulting intermediate is called PGAL. e Ten of the PGAL get phosphate groups from ATP. In terms of energy, this primes them for an uphill run—for the endergonic synthesis reactions that regenerate RuBP. 6 RuBP 12 PGA 12 ATP 6 ADP Calvin-Benson cycle 12 ADP + 12 Pi 6 ATP 12 NADPH 4 Pi 12 NADP+ d The phosphorylated glucose enters reactions that form carbohydrate products—mainly sucrose, starch, and cellulose. c Two of the twelve PGAL molecules combine to form a molecule of glucose with an attached phosphate group. 10 PGAL 12 PGAL 1 Pi phosphorylated glucose Fig. 6-10, p.101

Fig. 6-11, p.102

Fig. 6-12, p.103

end products (e.g., sucrose, starch, cellulose) Light- Dependent Reactions sunlight H2O O2 ADP + Pi ATP NADP+ NADPH Light- Independent Reactions Calvin-Benson cycle CO2 H2O phosphorylated glucose end products (e.g., sucrose, starch, cellulose) Fig. 6-13, p.104

p.104

p.105a