Questions? Comments? Please contact Dr. Phillip McClean or Christina Johnson.

OVERVIEW
Flythrough Tour
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MOLECULAR PROCESSES
Transcription
Regulated Transcription
mRNA Processing
mRNA Splicing
Translation
Lac Operon
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CELLULAR PROCESSES
Protein Trafficking
Protein Modification
Protein Recycling
Insulin Signaling
Constitutive Secretion
Regulated Secretion
Mitochondrial Protein Transport
Mitosis
Meiosis
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CELLULAR ENERGY CONVERSION
Atp Synthase (Gradients)
Electron Transport Chain
Photosynthesis (Light Reaction)
Photosystem II
Glycolysis (Overview)
Glycolysis (Reactions)
Citric Acid Cycle (Overview)
Citric Acid Cycle (Reactions)
Energy Consumption
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HOME >PHOTOSYNTHESIS (LIGHT) > FIRST LOOK

Photosynthesis (Light): First Look

The following images attempt to illustrate the major complexes and events involved in the light reactions of photosynthesis. Clicking on each of the thumbnail images will bring up a larger, labeled version of the described scene.

To see the Flash movie for the following sequence of images, click here.

The light reactions of photosynthesis involve several protein complexes. The complexes are embedded within the chloroplast's thylakoid membrane.

The first complex uses the energy from photons of light to excite electrons.

After two electrons have been excited, they are tranferred to a mobile carrier protein (magenta). The carrier also picks up two hydrogen ions, also known as protons.

The tranferred electrons are replaced by the splitting of water molecules. After two water molecules have been split, one molecule of O2 is made.

The mobile carrier transports the electrons to the second complex (yellow) and releases the two protons across the membrane.

As the two electrons are transferred through the second complex, it pumps two more hydrogen ions across the membrane.

The electrons are then tranferred to a second mobile carrier (dark blue).

The second carrier transfers the electrons to the third major complex.

The third complex uses photons to re-energize the electrons, after which they are transferred by another mobile carrier (purple) to the fourth complex (pink).

The fourth complex combines the two electrons, one proton, and a molecule of NADP+ to create a molecule of NADPH.

ATP synthesis occurs at a fifth complex. It is powered by the hydrogen ion gradient created by the protons that were pumped across the membrane.

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