Chloroplasts1. plants (leaves)2. algae

ADP + Pi + energy* ATP**Light energy from the sun

Energy captured from sunlightThis energy used to drive ATP synthesis

- light reactions

Energy in ATP used to drive the synthesis of organized molecules

6CO2 + 12 H2O + *energy glucose**Energy comes from the hydrolysis (breakdown) of ATP.

- light independent reactions

Photosynthesis

6CO2 + 12 H2O + light C6H12O6 + 6H2O + 6O2

Chloroplast Structure 1. thylakoids

- chlorophyll pigments in membrane (photosystem)2. grana3. stroma

Photosystem1. pigments “capture” photons2. excites an electron

3. energy of the electron is passed through the system4. energy transferred to membrane-bound proteins on the thylakoid membrane

Photons: Electromagnetic spectrum

Plants absorb mainly red and blue.Pigments only absorb photons of particular wavelengths.

Pigments are molecules developed for absorbing photonsRetinal

found in the human retina absorbs light in the “visible spectrum”

Some organismal pigments absorb outside the visible spectrum

Chlorophylla and b forms

absorb red and blue and reflect green

Chlorophyll is extremely efficient at capturing a narrow range of photons.

It excites an electron whose energy is passed through the pigment.

Carotenoids- absorb light at different wavelengths than chlorophyll- absorb blue and green and reflect orange and yellow

Making Glucose: C6H12O6

Need H1. there’s no H in CO2

2. reducing power- source of attachable H- from H2O

There is a different chlorophyll which absorbs another photon (Photosystem I).

excited electron on H atom transferred to NADP

NADPH carries H to growing carbon chain of glucose.Energy from that electron used to “stick on” H

Calvin CycleC3 photosynthesis