Light Dependent reactions

photosystems

pigment centers found in thylakoid membrane - capture light energy during photosynthesis

pigments

absorb light energy, different pigments have different wavelengths that can be absorbed

what do photons of light do?

excite electrons to higher energy states - energy is transferred through the photosystem until it reaches the center

electrons lost from PS2 are replaced how?

by breaking water - where oxygen released by plants come from

chemiosmosis

build up of H+ ions in the membrane for powering ATP synthase in ATP production

light dependent reaction 1 (noncyclic)

light charges electrons in Photosystem 2

light dependent reaction 2 (noncyclic)

electrons go to cytochrome complex, used to put H+ ions into the thylakoid membrane

light dependent reaction 3 (noncyclic)

electrons go to Photosystem 1 where they get recharged by light

light dependent reaction 3a (noncyclic)

the electrons are picked up by NADP and NADPH to be used in Calvin cycle

light dependent reaction 4 (noncyclic)

H+ ions form chemiosmotic gradient to power ATP synthase (ATP used in the Calvin cycle)

cyclic Light Dependent reaction 1

electrons are energized by light in PS1, move back to cytochrome complex - energized electrons used to create chemiosmotic gradient of H+ ions - power ATP synthase

cyclic Light Dependent reaction 2

electrons move from cytochrome complex back to PS1 where they are energized by light - reaction repeats

cyclic light dependent reaction - what isn’t released, not used, not involved, or not created

no water is used, no NADPH is created, no PS2 involved, no oxygen released

pigments and color

the color you see is the color that is being reflected (main pigment in plants is chlorophyll)

pigment molecule composition

porphyrin ring contains alternating single and double bonds (capable of having electrons move to a higher energy level)

where are pigments found?

in the thylakoid

what are proteins and pigments arranged in?

in photosystems