Energy Capturing Pathways I. Introduction A. History

1. VanHelmont,1630, proved plants need 2. Priestly, 1772, proved plants need 3. Ingenhaus, 1779, proved plants need 4. DeSaussure, 1804, organized all the pieces 5. Van Neil, 1930, water gas (phlogiston) sunlight proved hydrogen in the glucose comes from splitting water

B. Reduction/Oxidation Reactions

1. Redox = giving and receiving of electrons or energy Figure 9.3

C. NADP + and Energy Transfer

Figure 9.4

II. Photosynthesis A. Organisms

1. Autotrophs are organisms that can fix energy into carbon molecules. Figure 10.2

B. Structures

1. Chloroplasts Figure 10.3

C. Background Info.

1. Light Properties Figure 10.6

1. Light Properties Figure 10.7

2. Pigments Figure a. Chlorophylls are primaryand reflect greens.

2. Pigments b. Xanthophylls are secondary and reflect yellows.

2. Pigments c. Carotenoids are secondary and reflect oranges and protect chlorophylls.

2. Pigments Figure 10.9

III. Light Dependent Reactions A. Electron Excitation

Figure Magnesium absorbs light energy and electrons get excited

B. Where

1. Chloroplasts  light dependent reactions via chlorophyll pigments in the thylakoid membrane of chloroplasts Figure 10.12

C. Steps

1. Non-cyclic electron flow Figure 10.13

Non-cyclic Steps a. Light excites electrons of magnesium (oxidizes) of chlorophyll of photo-system II and I.I. b. Electrons from II are passed through an ETC to make ATP, while electrons from I are passed through an ETC to reduce NADP +. c. Electrons from II are used to backfill I chlorophyll that lost electrons to NADP +. d. Water is split by II to fill electrons lost to I by stealing electrons from hydrogen and provide a hydrogen to form NADPH.

2. Cyclic electron flow Figure 10.15

Cyclic Steps a. Light excites electrons of magnesium (oxidizes) of chlorophyll of photo-system I only. b. Electrons from I are passed through an ETC to make ATP only. c. Electrons from I are used to backfill I magnesium of the original chlorophyll. d. Water is not split.

Figure 10.17

D. Outcomes

The ATP and NADPH  chloroplast stroma used to energize CO 2 (ATP) & add hydrogen (NADPH) The O2 O2 to the stomata to be expelled or to mitochondria Do plants need to keep expelling O2 O2 for their benefit? Or yours?

IV. Light Independent Rxns. A. Where

1. Chloroplasts  The eight step process (Calvin cycle, the light independent reactions, or the DARK reactions) in chloroplast’s stroma. Figure 10.3

B. Steps

Figure 10.18

a. Rubisco attaches 3CO 2 to RuBP b. Requires 6ATP and 6NADPH to make 6G3P c. Separate 1G3P and hold in reserve d. Rearrange other 5G3P back into RuBP requiring 3ATP e. Repeat as long as you have enough ???? 1Glucose requires18ATP +12NADPH

C. Outcomes What to do with the glucose?

V. Alternative Strategies A. Photorespiration 1. Definition 2. Mechanism

B. C3 C3 Plants 1. Definition 2. Mechanism

C3 C3 plants go senescentrice, wheat, some grasses, and soybean

C. C4 C4 Plants 1. Definition 2. Mechanism

C4 C4 plants turn CO 2 into acid molecules then break up to give CO 2 to Rubisco sugarcane, corn, and other grasses Figure 10.19

D. CAM Plants 1. Definition 2. Mechanism

CAM plants completely separate light from dark reactions cactus, pineapples, and succulents

C4 C4 versus CAM plants Figure 10.20

Figure 10.21

Learning is the key to growing.