Photosynthesis

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Slide 50

Photosystem I

Discovered First

Active in the final stage of the Light Dependent Reaction

Made of 300 molecules of Chlorophyll

Almost completely chlorophyll a

Slide 51

Photosystem II

Discovered Second

Active in the beginning stage Of the Light Dependent Reaction

Contains about equal amounts of chlorophyll a and chlorophyll b

Slide 52

Photosynthesis Begins

Photosystem II absorbs light energy

Electrons are energized and passed to the Electron Transport Chain

Lost electrons are replaced from the splitting of water into 2H+, free electrons, and Oxygen

2H+ pumped across thylakoid membrane

Slide 53

Photosystem I

High-energy electrons are moved to Photosystem I through the Electron Transport Chain

Energy is used to transport H+ from stroma to inner thylakoid membrane

NADP+ converted to NADPH when it picks up 2 electrons & H+

Slide 54

Phosphorylation

Enzyme in thylakoid membrane called ATP Synthase

As H+ ions passed through thylakoid membrane, enzyme binds them to ADP

Forms ATP for cellular

Slide 55

Slide 56

Light Reaction Summary

Reactants:

H2O

Light Energy

Energy Products:

ATP

NADPH

Slide 57

Light Independent Reaction

ATP & NADPH from light reactions used as energy

Atmospheric C02 is used to make sugars like glucose and fructose

Six-carbon Sugars made during the Calvin Cycle

Occurs in the stroma

Slide 58

The Calvin Cycle

Slide 59

The Calvin Cycle

Two turns of the Calvin Cycle are required to make one molecule of glucose

3-CO2 molecules enter the cycle to form several intermediate compounds (PGA)

A 3-carbon molecule called Ribulose Biphosphate (RuBP) is used to regenerate the Calvin cycle

Slide 60

Slide 61

Factors Affecting the Rate of Photosynthesis

Amount of available water