Energy Capturing Pathways

I. Introduction

A. History

1. VanHelmont,1630, proved plants need2. Priestly, 1772, proved plants need3. Ingenhaus, 1779, proved plants need4. DeSaussure, 1804, organized all the pieces5. 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 10.10

a. Chlorophylls are primary

and reflect greens.

2. Pigmentsb. Xanthophylls are

secondaryand reflect yellows.

2. Pigmentsc. Carotenoids are secondary

and reflect oranges and protect chlorophylls.

2. Pigments

Figure 10.9

III. Light Dependent ReactionsA. Electron

Excitation

Figure 10.11

1. 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 Stepsa. Light excites electrons of magnesium

(oxidizes) of chlorophyll of photo-system II and 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 Stepsa. 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 CO2 (ATP) & add hydrogen (NADPH)The O2 to the stomata to be expelled or to mitochondria

Do plants need to keep expelling 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 3CO2 to RuBPb. Requires 6ATP and 6NADPH to make 6G3Pc. Separate 1G3P and hold in reserved. Rearrange other 5G3P back into RuBP requiring 3ATP

e. Repeat as long as you have enough ????

1Glucose requires

18ATP +

12NADPH

C. Outcomes

What to do with the glucose?

V. Alternative StrategiesA.

Photorespiration

1. Definition

2. Mechanism

B. C3 Plants1. Definition

2. Mechanism

C3 plants go senescent

rice, wheat, some grasses, and soybean

C. C4 Plants1. Definition

2. Mechanism

C4 plants turn CO2 into acid molecules then break up to give CO2 to Rubiscosugarcane, corn, and other

grasses

Figure 10.19

D. CAM Plants1. Definition

2. Mechanism

CAM plants completely separate light from dark reactionscactus, pineapples, and

succulents

C4 versus CAM plants

Figure 10.20

Figure 10.21

Learning is the key to growing.