Photosynthesis in plants converts solar energy into chemical energy using electrons and protons from water.

Introduction

The process of in plants involves a series of steps and reactions that use solar energy, water, and carbon dioxide to produce organic compounds and oxygen. There are two main sets of reactions: energy-transduction reactions (commonly called light reactions) and carbon-fixation reactions (commonly called dark reactions).

Image: Anna Guerrero, [email protected] / CC BY NC SA ‑ Creative Commons Attribution + Noncommercial + ShareAlike

The process of photosynthesis in plants involves a series of steps and reactions that use solar energy, water, and carbon dioxide to produce organic compounds and oxygen.

The Strategy

In the energy-transduction reactions, solar energy is converted into chemical energy in the form of two energy-transporting molecules, ATP and NADPH. When solar energy reaches plant cells and excites a chlorophyll molecule, it releases a high-energy electron. The release of this electron sets off a chain of electron-trading and energy-transferring events between several intermediary molecules, and the last molecule to form and hold the electrons in this chain is NADPH.

The excited chlorophyll molecule’s electrons need to be replaced, and these electrons come from water. With the help of enzymes and solar energy in a process called photolysis, water is split into electrons, protons (H+), and oxygen. The electrons go to the chlorophyll, while the protons contribute to a proton gradient that is used to power the synthesis of a second energy-carrying molecule, ATP. The oxygen is a byproduct of the whole process.

The chemical energy in NADPH and ATP is then used to power steps in the subsequent carbon-fixation reactions.

The Potential

Nature, through photosynthesis, has harnessed almost all of the energy we use today. Just like the wood some burn for fuel, fossil fuels like coal and natural gas derive their energy from photosynthesis that occurred long ago. Plants also feed us directly and indirectly via the animals we rely on for food, giving us the energy we need each day. Improving our understanding of this process could lead to improved agricultural methods that increase crop yields. We may develop new ways to harness, store, and manage energy. And we could learn how to efficiently use plants to store atmospheric carbon dioxide as we grapple with climate change.

Related Innovations

Related Strategies

Last Updated February 13, 2018