Physiological Diversity: Autotrophy Flashcards
What are the photosynthetic pigments?
Chlorophylls and Bacteriochlorophylls. They capture energy from light and are lipid pigments
What is the structure of chlorophylls?
Central Porphyrin ring, phytol tail inserted into membrane, cyclopentatnone ring.
What are Carotenoid Pigments?
Accessory pigments in cyanobacteria. They transfer energy to Chl or BChl.
What are Phycobilin Pigments?
Major light harvesting pigments of Cyanobacteria and Red Algae
What is the Structure of Phycobilin pigments?
Linear porphyrin molecles
Where do Phycobilin Pigments occur?
Between Thylokoid membranes
What Photosystems do the Light Reactions in Purple Phototrophs use?
Photosystem 1 only. D scheme
Describe the “D-Scheme” of Photosystem 1
Photosynthetic reaction center captures light at 870 to excite electrons. As energy is dissipated down the chain, H+ ions are being transported out of cel membranes to future recapture as ATP. Once electrons reach the Q pool, ATP is consumed to reduce NADP to NADPH by reverse electron flow. Electrons eventually lose all energy and are returned to initial donors. Water does not donate electrons.
Do Green Sulfur bacteria and Heliobacteria use reverse electron flow?
No. They are anoxygenic phototrophs. Their electrons are initially excited to a higher energy state so more energy is released through the D scheme.
What photosystems to the light reactions in oxygenic phototrophs use?
Photosystem 1 and 2. Z scheme
Describe the “Z-Scheme”
Water is the electron donor. Light energy excites Photosystem 2, electrons travel from photosystem 2 to photosystem 1. Light energy excites photosystem 1 at a different wavelength. Electrons directly reduce NADP
Describe the Dark Reactions (Calvin Cycle)
Uses NADPH and ATP from light reactions to fix CO2 and form hexose
Where do electrons come from in Anaerobic Photoautotrophy?
H2S
