Photosynthesis: Converting Light Energy into Chemical Energy

4 months ago

In this video I do an overview on photosynthesis, which is the process used by plants and other organisms to convert light energy into chemical energy, which can later be released to fuel the organism's metabolic activities via cellular respiration. There are 4 stages of photosynthesis: Light absorption, electron transport, ATP synthesis, and carbon fixation. The last stage involves the Calvin Cycle which changes sunlight into chemical energy and then splits water to liberate molecular oxygen and fixes carbon dioxide into sugar.

Time stamps:

Photosynthesis: Converting light energy to chemical energy: 0:00
Visualization of Earth's atmosphere by volume: 1:56
Photosynthesis has 4 stages: Light absorption, electron transport, ATP synthesis, carbon fixation: 3:32
Thylakoid membranes are the site of light-dependent reactions: 3:55
Electron micrograph of a thylakoid membrane: 7:49
Absorption is how matter (typical electrons) takes up a photon's energy: 9:51
Absorbed light removes electrons from a donor (water) to a primary electron acceptor, termed a quinone: 15:19
Transport of electrons is coupled to the movement of protons (or hydrogen) forming a pH gradient analogous to the proton-motive force: 25:58
Movement of protons down their concentration gradients is coupled to synthesis of ATP: 32:19
NADPH and ATPs generated by electron transport and ATP synthesis provide energy and electrons to synthesize glucose by fixing CO2 into existing organic carbon compounds via the Calvin Cycle: 35:14
Illustration of the Calvin Cycle: 38:11
Carbon fixation converts inorganic carbon (typically CO2) into organic compounds by living organism: 40:45
Chemosynthesis converts carbon containing molecules into organic matter via oxidation of inorganic compounds or ferrous ions as energy, rather than sunlight: 41:18