Photoautotrophs, which include plants, algae, bacteria, and Euglena, are organisms at the base of the food web that convert light energy from the sun into chemical energy stored in sugars.

The chlorophyll in plants captures energy in the form of red and blue light

Light-dependent reactions during photosynthesis convert sunlight into chemical energy, stored within the bonds of molecules such as ATP and NADPH. Rather than being absorbed for these reactions, most green light is reflected, causing most plants to appear green.

Instead of consuming water and carbon dioxide to produce oxygen and sugar, anoxygenic photosynthesis involves alternative reactants and products.

An overview of oxygenic photosynthesis, which releases oxygen from breaking down water

Within the membranes of chloroplasts, electrons in pigments are energized by light and transferred across a series of molecules until they create the energetic NADPH molecule. This transfer also powers a hydrogen pump, which creates an ion imbalance that, when relieved, produces energetic ATP molecules. Outside the membranes, both NADPH and ATP are used to synthesize G3Ps, which are funneled into other metabolic pathways to produce sugars.

Rubisco, the crucial enzyme powering photosynthesis

Photosynthesis is the crucial process by which plants absorb sunlight, take up water, and breathe in carbon dioxide, prompting chemical reactions that result in the byproducts sugar and oxygen. A key enzyme, rubisco, is responsible for it all, but it is inefficient. This video explores the key protein and reveals fascinating facts about oxygen and photosynthesis.

Understanding the role of photosynthesis as a sink within the carbon cycle

Photosynthetic organisms are net carbon absorbers, pulling carbon dioxide from the atmosphere and storing it in organic compounds and within soil. Approximately one-third of humanity's carbon emissions are stored by these organisms.

How the pigments that absorb light for photosynthesis contribute to plants' green color

Although light energy is captured to power the reactions that produce the building blocks of starch, cellulose, glucose, and other sugars, chlorophyll a and b are most sensitive to violet, blue, orange, and red light, leaving green light mostly unabsorbed. This green light is instead reflected, giving most plants this color appearance.

How artificial photosynthesis can help make plastics and fuels using sunlight

These systems link a molecular light absorber to a catalyst that can synthesize fuels—such as ethanol—and ethylene, a precursor to plastics, in a carbon-neutral manner. Because these byproducts have greater energy concentrations than the carbohydrates produced by photosynthetic organisms, research is ongoing to engineer the necessary catalysts.

The three categories of photosynthesis, which each help plants survive in different environments

In the vast majority of plants, C3 photosynthesis produces three-carbon intermediate molecules in the Calvin cycle within the cells of leaves. Plants in hot, dry climates use C4 photosynthesis across two types of cells to produce four-carbon molecules before the Calvin cycle. Plants in drought conditions use CAM to store carbon dioxide as an acid at night, minimizing water loss.

Virtually all plants are biofluorescent because their photosynthesis is powered by chlorophyll, a pigment that glows red as a way to get rid of excess energy when exposed to ultraviolet light.

Some corals absorb harmful ultraviolet radiation and re-emit it as visible light, thereby protecting symbiotic algae within their tissues and providing them with energy for photosynthesis.

The Amazon rainforest is considered the 'lungs of the Earth,' but it contributes less than a quarter of the oxygen of phytoplankton—microscopic plants, algae, and bacteria capable of photosynthesis.

View a gallery of plants made to shine using ultraviolet-induced visible fluorescence photography, in which organisms re-emit the ultraviolet light they are exposed to in vibrant, glowing colors.

Imagining if humans could perform photosynthesis and how it would change our anatomy

Since chloroplasts reflect green light, becoming photosynthetic would give our skin a green appearance. Because photosynthesis has efficiencies of only 5% to 9%, and humans burn 2,000 Calories daily compared to about 200 burned by a tree, becoming photosynthetic would also require us to adopt a less active, sun-filled lifestyle.

Learn about endoliths, the polyextremophiles that thrive inside rocks

These organisms include species that live in Antarctica, where they perform photosynthesis using light and water that makes it through pores in sandstone. Others residing in Earth's crust can survive temperatures reaching 60 degrees Celsius (140 degrees Fahrenheit) while generating energy through chemical reactions involving nutrients and gases trapped in rocks.

Early Earth lifeforms likely made energy via mineral reactions, not sunlight

Earth's initial atmosphere was filled with carbon dioxide, methane, and water, with most oxygen locked away in the rocky crust. Over time, bacteria evolved to slowly release that oxygen into the atmosphere by breaking down rock.

How does your body turn food into energy?

Cells get energy via a process known as cellular respiration, which involves turning glucose into ATP or adenosine triphosphate. Breaking the phosphate bonds of ATP results in usable energy being released into cells, which can then use that energy to power biological processes. This 10-minute video explains how glucose turns into ATP, giving the body the energy it needs to survive.

Solar power is converting the sun's energy into thermal or electrical energy

Solar energy is the most abundant renewable energy resource. It can be captured in photovoltaic cells to generate electricity, solar heating and cooling technologies for temperature control, and concentrated solar power to drive steam turbines.

Single-cell organisms have circadian clocks that direct daily biochemical routines

Cyanobacteria, a type of light-sensitive bacteria, use this clock to signal when to alternate between making organic compounds through photosynthesis and when to convert atmospheric nitrogen into usable ammonia. Upregulating photosynthetic machinery before dawn helps ensure efficient photosynthesis.

Artificial photosynthesis turns CO₂ into sustainable fuel

Carbon conversion focuses on a central perplexing question: if carbon dioxide is a leading driver of climate change, and fossil fuels are made of carbon-based molecules, can we devise a way to convert CO₂ into useful alternatives efficiently? This video breaks down a potential pathway using artificial photosynthesis, which uses sunlight to convert CO₂ into fuel.

Algae can capture carbon dioxide at rates up to 50 times faster than land-based plants and can be grown in tanks that use one-tenth the land footprint of terrestrial plants.

Astronauts on the International Space Station have tested an algae-powered bioreactor that converts carbon dioxide, water, and light into oxygen and edible, protein-rich biomass.

Watch a time-lapse from space of photosynthesis across Earth

Using NASA satellite imagery, carbon absorption can be tracked and serves as a proxy for photosynthetic activity on land and in the oceans. Over the course of a year, seasonal changes can be observed as plants become dormant in the fall and active again in the spring.

Bioluminescent organisms produce their own light through chemical reactions involving unstable, energetic molecules, while biofluorescent organisms almost immediately re-emit light shone on them, but at a different wavelength.

Electrogenic animals generate their own electricity within an electric organ by changing the pattern of electrical charges in disc-shaped cells called electrocytes.

Solar energy alone can fully power the world if transmission hurdles can be resolved

When light strikes a photovoltaic cell, electrons are loosened, which travel through a circuit where the energy can be used. Distributing energy from high solar intensity regions and storing energy for non-daylight hours is logistically challenging and costly.

Evidence suggests the first cells on Earth were bacteria

About 4 billion years ago, these single-celled organisms harvested carbon dioxide and sunlight to produce their own food and oxygen, setting the stage for the evolution of oxygen-breathing life forms. Archaeabacteria, which thrive on inorganic molecules in extreme habitats on Earth today, were also among the earliest organisms.

Explore the efficiency of photosynthesis under various conditions

In this simulation, users can track how the cellular concentrations of ATP, NADPH, glucose, and oxygen vary over time in response to changes in temperature, acidity, carbon dioxide concentration, and the properties of incoming light. Through multiple trials, users can identify the optimal conditions for photosynthetic reactions.

What fuels the sun?

The sun is our biggest source of heat and light, but how does this massive powerhouse continue to produce such amazing energy? Basically, it's a fusion reactor. At its core the sun produces all that solar energy through hydrogen fusing and converting into helium, over and over again. Learn more about the entire amazing and explosive process here.

Metabolism, a collection of chemical reactions at the cellular level, processes food and converts it into energy to power the body.

Why the abundance of RuBisCO in photosynthetic cells may come from its inefficiency

Despite pulling about 115 billion tons of carbon dioxide from the atmosphere to build organic molecules each year, the enzyme instead binds oxygen at least one in five times, needlessly costing cells energy. To compensate for this and its processing of no more than 10 molecules per second—versus thousands processed by a typical enzyme—it's become the most abundant enzyme on Earth.

How scientists are improving on photosynthesis

Researchers increased yield in soy plants by making them better at photosynthesis, the process that powers life. The findings hold promise for feeding a warming world.

The history of Earth's breathable atmosphere, made possible by photosynthetic bacteria

Between 3.2 billion and 2.8 billion years ago, threadlike microorganisms called cyanobacteria began consuming available water vapor, carbon dioxide, and sunlight to produce oxygen. However, molecules released from Earth's interior by volcanoes consumed this oxygen via chemical reactions, preventing it from accumulating until volcanism had sufficiently decreased about 2.4 billion years ago.

Massive blooms of microscopic algae called dinoflagellates produce the neon blue light seen in glowing tides.

View a sample of the bioluminescent tree of life

This diagram shows 42 different light-producing organisms, from bacteria and fungi to worms, fish, and crustaceans. It illustrates how the ability to produce light has appeared multiple times across the tree of life, rather than stemming from a single ancestor.

In the photovoltaic effect, light generates electricity by creating a charge imbalance after knocking electrons out of atoms in the semiconducting materials of solar cells.

Some organelles are believed to have once been independent cells

Mitochondria and chloroplasts, which are both responsible for energy production in cells, have DNA distinct from that of their host cells and are surrounded by cellular membranes resembling those of bacteria. Through symbiogenesis, these and other specialized structures were absorbed into larger cells, forming the modern-day biological units.

Watch underwater photosynthesis make water look like champagne

In shallow waters where sunlight can reach, photosynthetic reactions absorb water and dissolved carbon dioxide, producing bubbles of oxygen at the surface of plants. As these bubbles rise to the water's surface, a fizzy appearance is created.

Satellites can be used to measure photosynthetic activity worldwide by observing the red, biofluorescent light emitted by chlorophyll in plants.

Molecules derived from algae can be found in foods such as ice cream, salad dressings, brownie mix, and gravies, as well as in products such as toothpaste, multivitamins, and egg substitutes.

The research pipelines being explored by the RIPE Project to improve photosynthesis

These include engineering plants with faster stomata, which would allow photosynthesis to resume more quickly amid fluctuations in available light due to clouds or shading from other plants, and resolving bottlenecks in the regeneration of RuBP, the molecule to which carbon dioxide is fixed during photosynthesis to initiate the Calvin cycle. (Some readers may experience a paywall.)

The term 'symbiosis' was coined during the study of lichens—composite organisms in which algae or cyanobacteria partner with a fungus, alongside bacteria.

An explanation of the Calvin cycle, including why it needs to run six times to create glucose

Each run of this second phase of photosynthesis begins with a five-carbon molecule called RuBP, which gains an additional carbon atom when carbon dioxide (CO₂) is attached. Across six cycles, the six six-carbon molecules—36 carbon atoms in total—are processed into 12 three-carbon sugars, which can be used to generate glucose, and six RuBP molecules, enough for each cycle to restart.

Green algae have lived on Earth for about 1 billion years, roughly twice as long as the first plants.

Extremophiles were likely to have been Earth's first, and are expected to be its last, organisms

Their ability to survive in an enormous range of environmental conditions, including some resembling what has been modeled to have existed relatively shortly after Earth's formation, makes them the leading candidates for enduring the increasing solar intensity and the subsequent effects (e.g., zero-oxygen atmosphere, evaporated oceans) expected in the coming billions of years.

Learn how chloroplasts—the photosynthesis factories—may have once been independent cells

Possessing DNA of their own that differs from that of their host cell and surrounded by cellular membranes like those observed in bacteria, chloroplasts are believed to have evolved from a cyanobacterial cell. The endosymbiotic theory explains that these organelles were absorbed into larger cells, leading to the photosynthetic cells seen today.

Bioluminescence provides organisms with a method of hunting, defense, or mating

Unlike glow sticks, bioluminescent reactions use renewable resources like oxygen and ATP. This ability allows fireflies to mate and deter predators, anglerfish to confuse and attract prey, and deep-sea shrimp to defend themselves by vomiting glowing slush.

View examples of luciferin, the light-emitting molecule behind bioluminescence

Bioluminescent marine organisms rely on various unique luciferins, including Cypridina-type luciferin in seed shrimp and chlorophyll-based dinoflagellate luciferin, to react with oxygen to produce light. These chemicals require unique catalysts to help them bind with oxygen.

If the sun disappeared, we would not know about it for 8 minutes and 20 seconds, at which point the Earth would suddenly move in a straight line on its way out of the solar system.

How MIT researchers have used genetic mutations to improve photosynthesis efficiency

Recognizing that RuBisCO—a protein that binds carbon dioxide to other compounds to produce the building blocks of organic molecules—often mistakenly binds oxygen, scientists performed directed evolution experiments to modify the geometry of a bacterial version of the protein to cause it to preferentially interact with carbon dioxide over oxygen.

Breaking down the challenges of alkaline environments and how extremophiles survive them

These areas are far less acidic than the interiors of most organisms' cells, and this imbalance draws protons that are needed for various metabolic processes, including energy production, out of cells. To counter these effects, some alkaliphiles have developed stronger proton regulation across their cellular membranes and proteins that drive these processes with greater stability amid such acidity imbalances.