The Light Reactions

photosynthesis

using light energy from the sun to make organic chemicals, primarily carbohydrates (glucose)

light reactions

light energy is converted to ATP and NADPH, this occurs in the thylakoid membrane

thylakoid

membranes found in stacks within chloroplasts where light energy is converted to ATP and NADPH

granum

a stack of thylakoid membranes within a chloroplast

pigments

substances that absorb sunlight making photosynthesis possible

chlorophyll a

the primary pigment that absorbs sunlight for photosynthesis (absorbs lots of red and violet)

chlorophyll b

a pigment that absorbs blue light for photosynthesis

carotenoids

accessory pigments that make photosynthesis more efficient by absorbing light that chlorophyll a and b don't (orange, yellow and brown)

photosystem II

a few hundred pigment molecules and the proteins they are embedded in, location where the light reactions begin

photosystem I

a few hundred pigment molecules and the proteins they are embedded in, and place where electrons get re-energized by light to finish their trip to NADP+

primary electron acceptor

the first molecule that electrons join after being ejected by light energy from a photosystem

electron transport chain (e.t.c.)

a series of molecules that electrons travel down within the thylakoid membrane

water splitting enzyme

causes a chemical reaction with water to supply H+, e- and O2 (by-product) to photosynthesis

Opposite charges

causes H+ to cross thylakoid membrane when electron moves down the electron transport chain

NADPH and ATP

two high energy compounds produced by the light reactions

NADP+ and ADP

molecules that gave their energy to the Calvin cycle

water

ripped apart by enzymes to provide electrons (e-), hydrogen ions (H+) to the light reactions

NADP+ + H+ = 2 e-

these combine at the end of the electron transport chain to create NADPH

stroma

area that surrounds the grana and location of Calvin cycle

ATP synthase

H+ move through this which allows it to create ATP

inside of thylakoid membrane

location where H+ build up before shooting through ATP synthase