The process that converts solar energy into

chemical energy

Directly or indirectly provides all the

energy for the almost the entire living world

Sustain themselves without tanking nutrients

directly from other organism

Producers of the biosphere, creating organic

molecules from CO₂ and other inorganic

molecules

Almost all plants are photoautotrophs

Obtain their organic materials from other

organisms

The consumers of the biosphere

Almost all heterotrophs depend on photoautotrophs

directly or indirectly for food

Structurally similar to photosynthetic bacteria

Probably evolved form them and were incorporated

into plant cells

Structural organization allows for photosynthesis

The major locations of photosynthesis

Larger surface area for absorption of sunlight

and CO₂ than the stalk of the plant

Green pigment in chloroplasts

Allows for the absorption of light energy and drives

the synthesis of organic molecules in the

chloroplasts

-Microscopic pores in the leaves of the plant

-Allow O₂ and CO₂ to exit and enter

the plant (respectively)

Interior cells of the leaf

Main location of chloroplasts (typically each cell has

30-40 cholorplasts)

Thylakoids - connected sacs in the

chloroplasts

Grana - stacks of thylakoids

Stroma - a dense fluid filling the cholorplast

6CO₂ + 12H₂O + Light energy

→

C₆H₁₂O₆ + 6O₂ + 6H₂O

(water in the products is not the same water

as in the reactants)

Chloroplasts split water in Hydrogen and

Oxygen and incorporate the electrons

from H into sugar molecules

H₂O is oxidized

CO₂ is reduced

The Light Reactions (the photo part)

The Calvin Cycle (the synthesis part)

-Split H₂O

-Release O₂

-Reduce NADP⁺ to NADPH

-Generate ADP from ATP by

photophosphorylation

-Forms sugar from CO₂, ATP and NADPH

-Begins with carbon fixation, incorporating

CO₂ into organic molecules

Chlorophyll a

Chlorophyll b

Carotenoids

a - Absorption spectrum suggests that

violet-blue and red light works

best for photosynthesis

b - Broadens the spectrum of photosynthesis

carotenoids - Absorbs excess light that

might harm chlorophyll

Reaction-Center Complex - a type of protein complex

Light-Harvesting Complexes - Surround

the reaction-center and funnel the energy of

photons to the center

-Functions before Photosystem I

-Best at obsrobing a wavelength of 680 nm

-The reaction-center chlorophyll a of PSII is called

P680

Linear Electron Flow

-The primary pathway of electron flow

-Involves both photosystems

-Produces ATP and NADPH using light energy

Linear Electron Flow

(pathway)

-Photon hits a pigment

-Its energy is passed among pigments until

it excites the P680

-An excited electron from P680 is transferred to

the primary electron receptor

-P680⁺ is a very strong oxidizing agent

-H₂O is split by enzymes and the electron from

the hydrogen is transferred to P680⁺

-Oxygen is released as a byproduct

Electron Transport Chain

from PSII

-Each electron "falls" from the primary

electron acceptor of PSII to PSI

-The "fall" drives the creation of a proton gradient

across the thylakoid membrane

-Diffusion of H⁺ drives ATP synthesis