Photosynthesis

Lesson # 15

THE GREEN WORLD’S GIFT:

SOLAR ENERGY

Plants Transform the Solar Energy in Chemical Energy

Glucose is a more-ordered stated of matter than CO molecules. Therefore energy is not released, but it is taken.

2

CO 2 CO 2

CO 2

CO 2

CO 2

CO 2

More entropy

CHEMICAL ENERGY

Less entropy

Carbohydrates

Glucose

Glucose

PHOTOSYNTHESIS

Glyceraldehyde-3-phosphate (G3p)

It is the process by which certain group of organisms capture energy from

sunlight and convert it into chemical energy that is initially stored as

carbohydrates.

PHOTOSYNTHESIS

CO 2

+ ATP6 + NADPH6

+ 6 ADP + 6 NADP +

G3pglyceraldehyde-3-phosphate

From sunlightFrom atmosphere

(Energy, glucose, starch, proteins)

Photo synthesis

1-Photo or Light Reactions

2-Synthesis or Calvin Cycle

ATP NADPH 2O

CO 2Glyceraldehyde 3P

Waxy cuticle

Mesophyll cellsEpidermal

cells

Chloroplasts are the actual sites where photosynthesis takes place.

Light reactions take place in the thylakoid membrane

Calvin Cycle takes place in the stroma of chloroplasts

1- Photo or Light Reactions

Sunlight removes electrons from pigments and water and boosts them to a higher energy level to form Oxygen, ATP and NADPH.

Photosystems are multipart units that bring together electrons derived from water and energy derived from the sun.

e-

SUNLIGHT

H O2

e-

2 H + ½ O 2

+

ELECTRON TRANSPORT CHAIN

Antennae pigments

Reaction center

Photosystem IIENZYME

Photosystem I

e-

e-

e-

Photosystem I

ELECTRON TRANSPORT CHAIN

Antennae pigments

Reaction center

e-e-

ADP

ATP

Photosystem IITo Calvin

Cycle

E N E R G Y

e-e-

ELECTRON TRANSPORT CHAIN

e-e-

NADP+

SUNLIGHT NADPH

ELECTRON TRANSPORT CHAIN

To Calvin Cycle

e-e-

e-e-

ATP2o

ATP

1- LIGHT REACTIONS YIELD

This Oxygen accounts for more than 20% of the Earth’s atmosphere

To the Calvin Cycle ATP

NADPH

O2

2- Synthesis or Calvin Cycle

Krebs Cycle Calvin Cycle

CO 2

+ ATP6 + NADPH6

+ 6 ADP + 6 NADP +

G3pglyceraldehyde-3-phosphate

From Light ReactionsFrom atmosphere

Energy Glucose Starch Proteins