Photosynthesis Flashcards
Chlorophyll a
A primary pigment light energy excites electrons from magnesium
Exists as PSII 680 PSI 700
Photosynthetic pigments
Accessory pigments absorb wide range of light pass energy on
Thylakoids
Discs that contain photosynthetic pigments - v large SA
Light dependent stage
Photolysis splits water into hydrogen ions and electrons
Light hits pII and excites pair of e-
E- passed along cytochromes this releases energy which pumps h+ ions in
Light hits PI and exited 2e-
These join with NADP to for NADPred
H+ ions pump through ATP synthase
Forms atp
ATP synthase
EMF which converts kinetic energy into chemical energy
Light independent stage
Takes place in the stroma
6 full turns produce glucose
RuBP to 2 GP
RubisCo + CO2 carboxylation
GP forms amino acids and fatty acids
2GP to 2TP
2 NADPred -> 2 NADP
Uses 2 ATP
TP forms glycerol and hexose sugars
Reduction
2TP to RuBP
Regeneration
Uses ATP
Light intensity effects on Calvin cycle (low light)
Less light energy
Less ATP and NADPred formed
GP cannot convert to TP
TP cannot convert to RuBP
RuBP convert to GP CO2 levels = same
Limiatations of using photosynthometer
Take into account effect of respiration
Some O2 may dissolve into the water
Lamp= heat
Dark only 1 light source
Not acclimatised
Cyclic light dependent stage
Occurs at same time
Only produces ATP and uses only PSI
No O2 or NADPred