Download Chapter 10, part A

11/12/12
Ch 10: Plant Metabolism
Photosynthesis
In general
Types of chemical reactions in metabolism:
photosynthesis or
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Types of chemical reactions in metabolism:
redox reactions (moving electrons)
oxidized
(H atoms
reduced
carrying e-s)
How enzymes work (see also Ch 2 p25-6)
without enzyme
with enzyme
Enzyme reactions
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One of the circles of life
(but not everything can be
recycled; eg: energy)
Note: plants do both photosynthesis
AND cellular respiration
Anabolism: Producers
some bacteria, protists, plants
archaea & bacteria
(some bacteria don’t produce O2)
Chlorophyll a
heme
hydrophobic tail
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Absorption spectra of chlorophylls and a carotenoid
Why leaves appear green
Algae (K: Protista)
Group
PS Pigments
Reds
chl a, phycobilins, carotenoids
Dinoflagellates
chl a & c (usually), carotenoids
Diatoms
chl a & c, carotenoids
Xanthophytes
chl a & c, carotenoids
Chrysophytes
chl a & c, carotenoids
Coccolithophorids
chl a & c, carotenoids
Browns
chl a & c, carotenoids
Euglenoids
chl a & b, carotenoids
Greens
chl a & b, carotenoids
Photosynthetic structures:
Leaf, mesophyll cells and
chloroplasts
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Photosynthetic
structures:
Photosystems structures with pigments (held
by proteins) arranged to catch
light
A closer
look
antenna
(of pigments)
aka. light harvesting
complexes
PSI has
reaction
center
P700
PSII has
reaction
center
P680
Cyclic photophosphorylation makes ATP
involves just PS I
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Non-cyclic photophosphorylation: makes ATP & NADPH & O2
involves PS I and PS II
ets
How is ATP actually made? Photophosphorylation
Electron transport system/chain and chemiosmosis
What are the ATP & NADPH for? Calvin cycle = carbon fixation
(making sugars)
12 x 3C
2 x 3C
10 x 3C
12 x 3C
Rubisco
(6 x 5C)
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Photorespiration = Rubisco makes a mistake
(GA3P)
mistake
(GA3P)
Not useful
Alternative to standard C3 photosynthesis:
C4 photosynthesis pumps CO2 (in C4 acid) to Rubisco in bundle sheath cells
Kranz anatomy
(C4 acid
formed)
Alternative to
standard C3
photosynthesis:
CAM - when you
can t keep your
stomates open
during the day store up CO2 (in
C4 acid) at night
(C4 acid
formed)
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