In this transfer, the CO 2 is "reduced," or receives electrons, and the water becomes "oxidized," or loses electrons. Ultimately, oxygen is produced along with carbohydrates. Oxygenic photosynthesis functions as a counterbalance to respiration by taking in the carbon dioxide produced by all breathing organisms and reintroducing oxygen to the atmosphere.
On the other hand, anoxygenic photosynthesis uses electron donors other than water. The process typically occurs in bacteria such as purple bacteria and green sulfur bacteria , which are primarily found in various aquatic habitats.
For example, many bacteria use the bad-eggs-smelling gas hydrogen sulfide, producing solid sulfur as a byproduct. Though both types of photosynthesis are complex, multistep affairs, the overall process can be neatly summarized as a chemical equation. Here, six molecules of carbon dioxide CO 2 combine with 12 molecules of water H 2 O using light energy. The end result is the formation of a single carbohydrate molecule C 6 H 12 O 6 , or glucose along with six molecules each of breathable oxygen and water.
Similarly, the various anoxygenic photosynthesis reactions can be represented as a single generalized formula:. The letter A in the equation is a variable and H 2 A represents the potential electron donor. Pigments are molecules that bestow color on plants , algae and bacteria, but they are also responsible for effectively trapping sunlight. Pigments of different colors absorb different wavelengths of light. Below are the three main groups. Photosynthetic eukaryotic organisms contain organelles called plastids in their cytoplasm.
A molecule, chlorophyll Chl , is crucial for this process, since it absorbs sunlight. However, the way land plants produce their food is very different from the way plants in the oceans produce their food. Since it is difficult for light to reach underneath the water in the oceans, food production, scientifically called photosynthesis, becomes very slow.
Phycobiliproteins are proteins that make this job easier, by absorbing the available light and passing it on to Chl. These phycobiliproteins are found in tiny, invisible organisms called cyanobacteria. It is, therefore, very important for everyone to understand how cyanobacteria make their food, and what important roles the phycobiliproteins play in the process.
When you think of food, do you usually come up with images of your favorite food? This is a natural process, since food is important for every living thing.
To fulfill this basic need, all living things either make their own food or get it from some other source. Humans can eat both plants and animals. Some animals consume other animals, while some animals eat plants as their food.
Ultimately, we see that everybody on this planet is dependent on plants for their food. But then, what do plants eat? The process by which land plants produce their own food using sunlight and carbon dioxide is known as photosynthesis Figure 1.
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.
That's why some foods that we eat, like rice and grains, are packed with starch! Most plants contain a special colored chemical or pigment called chlorophyll that is used in photosynthesis. Chlorophyll is what absorbs the sun's energy and turns it into chemical energy. Not all the light energy from the sun is absorbed. In each sugar molecule created, there is a little bit of the energy from the Sun, which the plant can either use or store for later.
Imagine a pea plant. If that pea plant is forming new pods, it requires a large amount of sugar energy to grow larger. This is similar to how you eat food to grow taller and stronger. But rather than going to the store and buying groceries, the pea plant will use sunlight to obtain the energy to build sugar. When the pea pods are fully grown, the plant may no longer need as much sugar and will store it in its cells. A hungry rabbit comes along and decides to eat some of the plant, which provides the energy that allows the rabbit to hop back to its home.
Consider the process of photosynthesis. With the help of carbon dioxide and water, the pea pod used the energy from sunlight to construct the sugar molecules. When the rabbit ate the pea pod, it indirectly received energy from sunlight, which was stored in the sugar molecules in the plant. We can thank photosynthesis for bread! Wheat grains, like the ones pictured, are grown in huge fields. When they are harvested, they are ground into a powder that we might recognize as flour.
Humans, other animals, fungi, and some microorganisms cannot make food in their own bodies like autotrophs, but they still rely on photosynthesis.
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