Scientists have finally discovered how photosynthesis starts by setting it off with a single photon.
For the first time, researchers have observed how just one particle of light can trigger photosynthesis in bacteria—finally revealing the first step of the crucial process.
Light is the basis for almost all life on Earth. Using energy from the sun, plants, algae, and some bacteria create complex sugar molecules that serve as the foundations for most of nature’s food chains, but parts of this world-feeding chemical reaction have remained somewhat of a mystery—until now.
For the first time, researchers have observed the beginnings of photosynthesis, starting with a single photon.
“A huge amount of work, theoretically and experimentally, has been done around the world trying to understand what happens after the photon is absorbed, but we realized that nobody was talking about the first step,” Graham Fleming, a chemist at the University of California Berkeley and co-author of the new research, said in a statement. Fleming and his team described the process in a study published June 14 in the journal Nature.
When light hits a plant’s chloroplast—the sugar factory of the organelle world—it absorbs energy from the incoming photons and uses it to turn carbon dioxide and water into glucose and oxygen, thanks to a pigment called chlorophyll.
Scientists have known about this process since at least the late 1700s, but it’s taken much longer to unravel the granular details. A pair of French scientists first isolated chlorophyll in the early 1800s, and by the end of the century, botanist Theodor Wilhelm Engelmann had uncovered its role in absorbing sunlight, according to a 2019 paper published in the Annals of Botany. Researchers made more progress in determining the biochemistry of photosynthesis throughout the 20th century, discovering, for example, that excited electrons help to transfer energy through the chloroplasts.
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