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Bio 122 Fall 2015: Lecture 3: Energy Acquisition (Chpt 5)
I. Energy Acquisition
A. Energy sources
B. Obtaining Energy: Autotrophy
1. Chemosynthesis
2. Photosynthesis (C3 pathway)
a. Light reaction
i. Capture photon
ii. Use energy from photon to split water
iii. Use electron from splitting water to synthesize ATP & NADPH
b. Calvin cycle
i. Uptake of CO2
ii. Synthesis of 3-C compound (PGA)
iii. Synthesis of 6-C compound (glucose)
C. Photosynthesis constraints & solutions
1. Light
2. Temperature
a. rubisco – catalyst for 2 competing reactions
b. C4 photosynthesis (spatial separation of cycles)
i. Light reaction the mesophyll – 4-C compound created
ii. 4-C to bundle sheath, providing CO2 & 3-C compound for glucose synthesis
c. C3 vs. C4 photosynthesis
3. Water
a. CAM photosynthesis (temporal separation of cycles)
4. Nutrients
D. Heterotrophy
Figure 5.6 Absorption Spectra of Plant Photosynthetic Pigments
Photosynthesis: Light Reactions (sunlight required)
Chloroplast
Light Reactions
Dark Reactions
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Figure 5.7 Plant Responses to Variations in Light Levels (Part 1)
C3: Photosynthesis in
mesophyll cells
C4: Photosynthesis in
1) mesophyll cells
2) Bundle sheath cells
C4 Cycle
Calvin Cycle
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Figure 5.17 Examples of Plants with the CAM Photosynthetic Pathway
Problem 5.1: Some Like it Hot
Comparison of C3 and C4 Pathways
Simulation model:
http://sites.sinauer.com/ecology3e/problem05.html
Figure 5.16 Crassulacean Acid Metabolism (Part 1)
Figure 5.16 Crassulacean Acid Metabolism (Part 2)
Figure 5.15 C3, C4, and CAM Photosynthesis Compared
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