Photosynthesis PhotosynthesisConverting Light Energy into Chemical

EnergyConverting Light Energy into Chemical

Energy

I. PhotosynthesisI. Photosynthesis

A. Background

Photosynthesis drives and supports all life on earth (except at hydrothermal vents). Understanding this important reaction will help us better understand the limits and effects of human and other populations on our planet.

Sun provides energy->Plants make food->Consumers eat plants->

Consumers thank plants!

I. PhotosynthesisI. Photosynthesis

B. Location

• The reactions of photosynthesis occur within plant cells in the chloroplast. Chloroplasts contain pigments called chlorophyll, which capture light.

C. Products & Reactants of Photosynthesis

Light Energy

CO2 + H2OSugar + O2

Plant Cell

O2

CO2

Light- DependentReactions

CalvinCycle:

Energy:

ChloroplastLight

H2O

ATP

Sugar (Glucose)C6H12O6

H+ ions

Chlorophyll absorbs light

for light reactions

Other materials

D. Overview of Photosynthesis - In the chloroplasts of photosynthetic organisms, the energy of sunlight is transformed into the energy stored in the chemical bonds of carbohydrates (glucose)

Dark (Light-Independent)

Reactions

Q: What happens to the glucose after it is made by the plant cell?

NADPH

Captured by rubisco enzyme

Dark Reactions

E. A Closer Look at Photosynthesis

1. Light Reactions (Light Dependent)

• Light energy, absorbed by chlorophyll, splits water to store chemical energy (ATP), releasing hydrogen and oxygen

• H2O + light ATP (energy) + H+ + O2

2. Dark Reactions (Light Independent)

• The energy generated in the light reaction converts carbon dioxide and hydrogen ions into sugar (glucose)

• ATP(energy) + H+ + CO2 C6H12O6 (+ ADP +P)

Q: What is ATP?

ATP:• adenosine triphosphate

• the form of stored energy that is useable by cells

• Energy is stored and/or released when bonds between the phosphates are formed

or broken