CHLOROPHYLL PigmentsCHLOROPHYLL Pigments

• Chlorophyll a -Chlorophyll a - “grass green” main pigment. Other pigments absorb light and transfer energy to chlorophyll a

• Chlorophyll b -Chlorophyll b - “blueish-green” in plants, algae and photoautotrophic bacteria

Chlorophylls absorb very little of green and yellow-Chlorophylls absorb very little of green and yellow-green wavelengths of lightgreen wavelengths of light

ACCESSORY PigmentsACCESSORY Pigments• Carotenoids -Carotenoids - absorb the

wavelengths that chlorophylls miss– beta-carotene (appears orange,

in carrots)

– xanthophylls (appear yellow)

• Anthocyanins Anthocyanins - flowers, appear red and blue, red algae

• Phycobillins-Phycobillins- purples and blues

• Chlorophyll Molecule– composed of a

magnesium atom surrounded by a nitrogen containing

porphyrin ring.porphyrin ring.

Antenna ComplexAntenna Complex

A chloroplastA chloroplast

Light Dependent Light Dependent Reactions of Reactions of PhotosynthesisPhotosynthesis

Non-Cyclic Photophosphorylation

The STEPSThe STEPS

1. A photon of light strikes

Photosystem II reaction center. (p680)

The chloroplast absorbs

energy wavelengths best at 680 nanometers at PSII.

2. Electrons are excited and one e- jumps to a higher energy level as H2O is split (photolysis).

Oxygen is released.

3. The Primary Electron Acceptor passes the electron to an ELECTRON TRANSPORT CHAIN (E. T. C.)

4. ETC - within the thylakoid membranes of the chloroplast….

A series of enzymes, coenzymes and other proteins transfers electrons from one to another (BIOCHEMICAL PATHWAY)

The biochemical pathway consists of e- carriers

• PLASTOQUINONE (Pq)• a complex of

CYTOCHROMES (cyt)--- similar to hemoglobin molecule

• PLASTOCYANIN (Pc) (contains Copper)

The E.T.C.The E.T.C.

• The energy released through the EXERGONIC cascade through the E.T.C. powers the production of ATP via the enzyme ATP SYNTHASE and a PROTON PUMP

• ATP production is called PHOTOPHOSPHORYLATION

ANOTHER PHOTON ANOTHER PHOTON OF LIGHT HITS!!!!!!!!!OF LIGHT HITS!!!!!!!!!

5. Photosystem I (p700) is EXCITED and loses an electron…..

The electron from the E.T.C. replaces it…...

6. The electron is passed to another PRIMARY ELECTRON ACCEPTOR.

7. The e- moves through another electron transport chain E.T.C. (shorter)

--uses e-- carrier protein FERRODOXIN(Fd)

8. At the end of the ETC, and enzyme ( NADP+ ( NADP+ REDUCTASE ) REDUCTASE ) reduces NADP+ and stores the electron as

NADPH