Biology Lesson 10

Photosynthesis

a process where CO2 is reduced to glucose by the electrons gained from the oxidation of water which is power by the sun

Photosynthesis occurs in the

chloroplast of plant cells

Photosynthesis produces

ATP and NaDPH

chloroplast can be found in the

mesophyll cells (leaf)

stroma

semiliquid where the Calvin cycle occurs that contains thylakoids

thylakoid membrane

separates the stroma from the interior of the thylakoids

thylakoid membrane contains

chlorophyll responsible for capturing light energy

Photosystem

a complex of proteins and pigments that captures light energy and initiates photosynthesis

Photon

particle of light that acts as a bundle of energy

photoelectric effect

when a photon strikes a molecule and excited an electron allowing it to be removed

chlorophyll a

primary pigment in photosynthesis, absorbs blue and red light

chlorophyll b

accessory pigment, absorbs blue and orange light

carotenoids

absorbs blue and green light and has anti-oxidant properties

Antenna complex

contains lots of pigments that capture photons and pass their light energy to the reaction complex

reaction complex

site where light energy is converted into chemical energy and excited electrons are passed to an electron acceptor

photophosphorylation

electrons for H2O transfer to NaDP+ forming NaDPH and ATP

Chloroplasts use 2 photosystems

photosystem 1 (P700) and photosystem 2 (P680)

step 1 of light dependent reaction

photons are absorbed by photosystem 2 and H2O is split

step 2 of light dependent reaction

excited electrons are passed to b6f complex which pumps H+ into the thylakoid space

step 3 of light dependent reaction

electrons go to photosystem 1 where more photons are absorbed and more electrons are excited which generates NaDPH

step 4 of light dependent reaction

conversion of H+ to ATP through ATP synthesis and cheimosmosis

cylic photophosphorylation

when electrons from photosystem I are recycled to generate ATP instead of NADPH, allowing for increased ATP production

characteristics of light dependent reactions

reaction requiring light energy that occur in the thylakoid to produce ATP, NADPH, and O2

characteristics of light independent reactions

non-light energy reactions occurring in the stroma that use ATP and NADPH to synthesize organic molecules from CO2 (calvin cycle)

carbon fixation of calvin cycle

the attachment of CO2 to RuBP to create 2PGA which is catalyzed by rubisco

Reduction phase of Calvin Cycle

2PGA is converted into G3P through reactions involving ATP and NaDPH

Regeneration phase of Calvin Cycle

G3P is used to regenerate RuBP, allowing the cycle to repeat

Takes ___ cycles of calvin to make glucose

6

glucose is not a direct product of the calvin cycle

true, it synthesizes 2 molecules of G3P that are released during the reduction phase

photorespiration

when O2 is added to RuBP and catalyzed by rubisco releasing CO2 (reverse carbon fixation)

why does photorespiration occur

because of hot/dry climates that cause plants to close their stomata which traps O2 inside and blocks CO2

C4 Plants pathway

plants that add CO2 to PEP instead of RuBP

Negative of C4 plants pathway

requires 12 ATP to produce 1 glucose

CAM pathway

when plants take in CO2 at night adding it to PEP and store it in a vacuole which is then sent to the calvin cycle during the day