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Chapter: 8 Photosynthesis - Coggle Diagram
Chapter: 8 Photosynthesis
Light Reactions
uses energy
produces ATP, NADPH and O2
types
cyclic
requires PS 1
produces ATP
releases H+ into the lumen driving ATP synthesis
reaction centre P700
noncyclic
requires both PS 1 and 2
begins at PS 1
produces both ATP and NADPH in equal amounts
starts by breakdown of H2O
reaction centers P680 and P700
Chloplast
has pigments that enable maximum absorbance of light
contained by mesophylls
carries out photosynthesis
parts
grana
intermembrane space
inner and outer membrane envelopes
stroma
thylakoid system or lamellae
general information
H+
enhanced by H2O oxidation
dehanced by formation of NADPH
enhanced by ETC pumpimg H+ into the lumen
Photosystems (PS)
PS 1
contributes to H+ electrochemical gradient by depleting H+ from stroma
primary role to make NADPH
PS 2
oxidizes H2O generating O2 and H+
releases energy in ETC
transfer excited electrons to PS 1
contributes to H+ electrochemical
initial step in photosynthesis
redox machine
trophic levels
heterotroph
depends on others for energy and nutrients
autotroph
produces its own food using available chemicals or energy
photoautotroph
carries out photosynthesis
ATP synthesis in chloroplasts
achieved by photophosphorylation
driven by the flow of H+ from lumen to the stroma
photosynthesis facts
endergonic
CO2 reduced and H2O oxidized
anabolic
enhanced by less light intensity, more temperature and more water vapor
not sponteneous
zigzag scheme or energy curve
involves increase and decrease of electron energy
starts at PS 2 for lowest energy the proceeds to PS 1
enhancement effect
simultenous flashes of P680 and P700 doubles rate of photosynthesis
P680 activates PS 2
P700 activates PS1
Light independent or Dark Reactions
C4
hatch and slack pathway
first stable product is oxaloacetic acid
evolved mechanism to minimize respiration
first CO2 receiver is phosphoenol pyruvic acid
all reactions held in bundle sheath and mesophyll chloroplast
conserves water in dry warm climates
crassulean acid metabolism (CAM)
closes stomata during day to conserve water
for cactuses or desert plants
opens stomata at night
CO2 and oxaloacetate are converted to malate
CO2 is broken down during day for C3 cycle
C3
calvin belson cycle
first stable product is 3 carbon phosphoglyceric acid
first CO2 receiver is 1,5 ribulose biphosphate (RuBP)
all reaction held in mesophyll chloroplast
requires massive input of energy
phases
second: reduction and CO2 production
third: regenration of RuBP
first: carbon fixation
uses less energy in cooler environments
photorespiration
usage of O2 and liberating of CO2 when rubisco acts as oxygenase
favored when O2 is high and CO2 low
more likely in hot and dry environments