Photosynthesis Flashcards
Photosynthesis
Converting light energy into food
Chloroplasts
Site of photosynthesis in the plant cell; two membranes surrounding stroma; third membrane (thylakoids) inside the stroma
Chlorophyll
A green pigment within the thylakoid membrane
Stomata
Microscopic pores that permit oxygen, carbon dioxide, and water to flow through
Light reactions
The process of splitting water to produce ATP and NADPH, occurs in the thylakoid membranes
Calvin cycle
The process of fixing carbon dioxide to organic molecules
Pigment
A chemical that absorbs certain colors of light
Main types of pigment
Chlorophyll a, chlorophyll b, carotenoids
Photoprotection
The dissipation of excess light energy that could damage light cells
Photosystem
A reaction-center complex surrounded by light-harvesting complexes
Photosystem II
The first photosystem to function; contains P680 as the reaction-center chlorophyll
Photosystem I
The second photosystem to function; contains P700 as the reaction-center chlorophyll
Linear electron flow
The movement of excited electrons through PS II, down an electron transport chain, through PS I, and down a second ETC to reach NADP+
Cyclic electron flow
The cycle of electrons going from PS I to the first ETC, producing no NADPH but plenty of ATP
Chemiosmosis in plants
Converts light energy to ATP; proton gradient is pumped from stroma to thylakoid space
Calvin cycle product
G3P
Carbon fixation process
Rubisco catalyzes the attachment of carbon dioxide to RuBP, making 3-carbon intermediates
Reduction
3-carbon intermediates are reduced to G3P; some G3P leaves the cycle
Regeneration
The rest of G3P is built back into RuBP
Net gain/loss of Calvin cycle
9 ATP and 6 NADPH used
One G3P made
C3 plants
Plants where carbon fixation first produces a 3-carbon intermediate
Photorespiration
The process where rubisco consumes oxygen during the Calvin cycle, producing carbon dioxide and generating no sugar
C4 plants
Plants that have a precursor cycle to the Calvin cycle, which makes a 4-carbon intermediate
Mesophyll cells
Site of the C4 precursor cycle
Bundle-sheath cells
Site of the Calvin cycle in C4 plants
CAM plants
Plants that isolate a precursor and Calvin cycle by time, rather than location in different cells
