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Figure 14.26
Phototrophy
• To maximize light absorption, Halobacterium
salinarium archaea pack their entire cell membrane
with bacteriorhodopsin.
•
- The protein forms trimers that pack in hexagonal
arrays, forming the “purple membrane.”
Figure 14.27
Chlorophylls
• Each type of chlorophyll contains a characteristic
chromophore, light-absorbing electron carrier.
- Chlorophyll molecules
differ slightly in their
substituent groups
around the ring.
- These slight differences
alter their absorption
spectra.
Figure 14.29
Figure 14.31
• In purple bacteria, the efficiency
of photon uptake is increased
even more by the presence of
thylakoids.
- Extensive backfolding
of the photosynthetic
membranes in oval
pockets
Figure 14.32
Figure 14.35
Figure 14.34
Figure 14.33
Figure 14.36
Oxygenic Z Pathway
• Animation: Oxygenic Photosynthesis
Click box to launch animation
Overview of the Calvin Cycle
Figure 15.5
Mechanism of Rubisco
• Rubisco consists of small (S) and large (L) subunits.
•
- Catalyzes the condensation of CO2 to ribulose 1,5bisphosphate, and the splitting of the unstable 6C
intermediate into two 3C PGA molecules
Figure 15.6AB
Carboxysomes Contain Rubisco
• Many organisms contain the Rubisco complex within
polyhedral structures called carboxysomes.
• The carboxysome takes up bicarbonate (HCO3–), which
is then immediately converted to CO2 by carbonic
anhydrase.
- The CO2 is then
fixed by Rubisco.
Figure 15.8