Organisms which perform photosynthesis

Some scientists theorize that Oriental hornets may draw energy from sunlight, although this doesn't appear to be photosynthesis proper. Other researchers theorize that photosynthesis rarely evolved in animals for several reasons: Exposure to heat and ultraviolet light can be dangerous; the need for large surface areas conflicts with other survival strategies in animals; and there are health concerns associated with sugar-rich diets.

The Morphology of Algae. What Plants Live in the Deep Ocean? Ecological Importance of Algae. What Do Volvox Eat? List of Underwater Ocean Plants. Role of Algae in the Ecosystem. How Do Bacteria Respire?

What Are Good Protists? Roles of Cyanobacteria in the Ecosystem. How Does Seaweed Conduct Photosynthesis? What Are the Characteristics of the Protista Kingdom? Is Algae a Decomposer, a Scavenger or a Producer? A deer obtains energy by eating plants. A wolf eating a deer obtains energy that originally came from the plants eaten by that deer.

The energy in the plant came from photosynthesis, and therefore it is the only autotroph in this example Figure 5. Using this reasoning, all food eaten by humans also links back to autotrophs that carry out photosynthesis. Major grocery stores in the United States are organized into departments, such as dairy, meats, produce, bread, cereals, and so forth.

Each aisle contains hundreds, if not thousands, of different products for customers to buy and consume Figure 5. Although there is a large variety, each item links back to photosynthesis. Meats and dairy products link to photosynthesis because the animals were fed plant-based foods. The breads, cereals, and pastas come largely from grains, which are the seeds of photosynthetic plants.

What about desserts and drinks? All of these products contain sugar—the basic carbohydrate molecule produced directly from photosynthesis. The photosynthesis connection applies to every meal and every food a person consumes. Photosynthesis requires sunlight, carbon dioxide, and water as starting reactants Figure 5. After the process is complete, photosynthesis releases oxygen and produces carbohydrate molecules, most commonly glucose. These sugar molecules contain the energy that living things need to survive.

The complex reactions of photosynthesis can be summarized by the chemical equation shown in Figure 5. Although the equation looks simple, the many steps that take place during photosynthesis are actually quite complex, as in the way that the reaction summarizing cellular respiration represented many individual reactions.

Before learning the details of how photoautotrophs turn sunlight into food, it is important to become familiar with the physical structures involved. In plants, photosynthesis takes place primarily in leaves, which consist of many layers of cells and have differentiated top and bottom sides. The process of photosynthesis occurs not on the surface layers of the leaf, but rather in a middle layer called the mesophyll Figure 5. The gas exchange of carbon dioxide and oxygen occurs through small, regulated openings called stomata.

In all autotrophic eukaryotes, photosynthesis takes place inside an organelle called a chloroplast. In plants, chloroplast-containing cells exist in the mesophyll. Chloroplasts have a double inner and outer membrane. While carbon dioxide is absorbed by the leaves, the sunlight is captured by a chemical molecule in the plant, called chlorophyll Chl.

All photosynthetic organisms contain Chl. Plants in the oceans face problems with light availability. The blue and green portions of light penetrate into the water more than the yellow and red portions of light do Figure 2. Luckily, ocean plants get help in producing food from such limited light and carbon dioxide, from tiny microscopic microbes called cyanobacteria also known as blue-green algae.

These microbes have adapted to dim light conditions, and they carry out photosynthesis both for themselves and for the benefit of other living things. Cyanobacteria are ancient microbes that have been living on our earth for billions of years. Cyanobacteria are said to be responsible for creating the oxygen-filled atmosphere we live in [ 1 ]. For carrying out photosynthesis in low light conditions, cyanobacteria have the help of proteins called phycobiliproteins , which are found buried in the cell membranes the outer covering of the cyanobacteria.

Phycobiliproteins play the role of assistants to Chl in aquatic water environments. Since light has a difficult time penetrating into the oceans, phycobiliproteins make this job easier by absorbing whatever light is available; they absorb the green portion of the light and turn it to red light, which is the color of light required by Chl [ 2 ]. However, changing the color of light is not as easy as it seems. The green light has to pass through different phycobiliprotein molecules, which absorb light of one color and give out light of another color.

The color that is given out is then taken up by a second phycobiliprotein, which turns it into a third color. This process continues until the emitted light is red, which can finally be taken up by Chl. For this whole process to take place, we have three different kinds of phycobiliprotein molecules arranged as a sort of a hat over the Chl molecule, as you can see in Figure 3.

These three kinds of phycobiliproteins are:. The reason phycobiliproteins absorb light of different colors is that they contain chemical molecules called bilins inside them, which give them their bright colors. These bilins are responsible for absorbing light of one color and emitting light of another color, thus causing a change in the color of light.

Advanced instruments have let us analyze the arrangement of these molecules and proteins in the cyanobacteria. We know that phycobiliproteins are shaped like disks [ 3 ], and the disks are stacked on top of each other to form the hat-like structure.

This assembly joins to the core, made of APC. This entire structure is linked to Chl, which accepts the red light emitted by APC.