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BIOL V04 Lecture: Photosynthesis (Ch 10)
© copyright 2015 Marta D. de Jesus
I. Which organisms are photosynthetic?
A. K: Bacteria
B. K: Archaea
C. K: Protista
D. K: (Land) Plantae
II. Oxygenic Photosynthesis
A. Overview
1. uses energy-producing processes
2. (dicot) leaf architecture
a. epidermis
b. mesophyll with photosynthetic parenchyma
c. vascular tissue
3. chloroplasts
a. 2 membranes
intermembrane space
b. stroma
c. grana of thylakoids
d. chlorophyll molecules
4. 2 sets of reactions
a. “photo”
b. “synthesis”
B. Light Dependent reactions
1. chlorophyll a
2. Evolutionarily, where did it come from?
3. Why is it green?
4. What does it do; why is it special?
fluorescence
5. reaction centers
a. photosystems
proteins
antenna pigments = accessory pigments
b. reaction center
6. How does the system function? Non-cyclic photophosphorylation
P680 reaction center (in photosystem II)
electron acceptors
P700 reaction center (in photosystem I).
reduce NADP+
PS II takes electron from H2O
ATP synthase
7. Comments:
a. “Z-scheme”
b. PS I vs. PS II
c. What does this resemble?
d. How are the ATPs made?
e. O2
8. What’s cyclic photophosphorylation?
C. Light Independent reactions = carbon fixation reactions = Calvin-Benson cycle
1. requires
2. use 3 CO2s
3. ribulose bisphosphate carboxylase-oxygenase
4. why do plants need both cyclic and non-cyclic?
III. Some photosynthesis modifications: in response to some problems
A. photorespiration
RUBISCO mistake
1 solution: C4 plants
a. special leaf anatomy
b. mesophyll cell
PEP carboxylase
c. bundle sheath
RUBISCO
B. high light, very dry environment e.g.: desert
CAM plants