Photosynthesis

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Slide 24

Julius Robert Mayer 1845

Proposed That Plants can Convert Light Energy Into Chemical Energy

Slide 25

Samuel Ruben & Martin Kamen 1941

Used Isotopes To Determine That The Oxygen Liberated In Photosynthesis Comes From Water

KAMEN

RUBIN

Slide 26

Melvin Calvin 1948

First to trace the path that carbon (CO2) takes in forming Glucose

Does NOT require sunlight

Called the Calvin Cycle or Light Independent Reaction

Also known as the Dark Reaction

Slide 27

Rudolph Marcus 1992

Studied the Light Independent Reactions

First to describe the Electron transport Chain

Slide 28

The Photosynthesis Equation

Slide 29

Pigments

In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments

Chlorophyll is the primary light-absorbing pigment in autotrophs

Chlorophyll is found inside chloroplasts

Slide 30

Light and Pigments

Energy From The Sun Enters Earth’s Biosphere As Photons

Photon = Light Energy Unit

Light Contains A Mixture Of Wavelengths

Different Wavelengths Have Different Colors

Slide 31

Light & Pigments

Different pigments absorb different wavelengths of light

Photons of light “excite” electrons in the plant’s pigments

Excited electrons carry the absorbed energy

Excited electrons move to HIGHER energy levels

Slide 32

Chlorophyll

There are 2 main types of chlorophyll molecules:

Chlorophyll a

Chlorophyll b

A third type, chlorophyll c, is found in dinoflagellates

Magnesium atom at the center of chlorophyll

Slide 33

Chlorophyll a and b

Slide 34

Chlorophyll a

Found in all plants, algae, & cyanobacteria

Makes photosynthesis possible

Participates directly in the Light Reactions

Can accept energy from chlorophyll b

Slide 35

Chlorophyll b