Photosynthesis:
Energy from light!
Photosynthesis is the process of turning the energy of light into sugars. These sugars are packed with energy usable by plants, people, or any plant-eating critter. Here are some basics of why photosynthesis is important, including a quick overview of what is occurring during photosynthesis.
Why it's Important
The fossil fuels that are the cornerstone of our energy began as carbon dioxide from the atmosphere. Through photosynthesis, ancient forests turned that carbon dioxide into organic compounds, leading to the their underground transformation into the crude oil we use today. Humanity is more dependent on photosynthesis than ever before. Thus, any product that stems from crude oil can be attributed to photosynthesis. All of our food's energy content can also be attributed to photosynthesis. Our way of life revolves around a process that we are actually unable to perform. Without photosynthetic organsisms, life on Earth would only exists among bacteria whose energy source is not related to the sun.
Overview
The basic formula for the process of photosynthesis is as follows:
Carbon Dioxide + Water + Light ---> Sugar + Oxygen
(In the Presence of Chlorophyll)
Figure 1 - http://static.howstuffworks.com/gif/irrigation-photosynthesis.gif
The Chloroplast : The site of photosynthesis
All forms of life are built by cells. A cell is the smallest portion of an organism. In more complicated forms of life, such as plants, people and bugs, different types of tissue are made by different types of cells that have specialized tasks. In trees, for example, the cells that make the trunk are specialized for transporting nutrients up and down the tree, while the leaves are wide and broad to capture light for photosynthesis. Those leaves have something that the bark cells do not, and those are chloroplasts. Chloroplasts are organelles. An organelle is a small body that performs certain duties within the cells. The chloroplasts are the organelles responsible for photosynthesis. Within these organelles lies the chlorophyll, which is where this entire process begins.
Structures found within the Chloroplast
Figure 2: http://micro.magnet.fsu.edu/cells/chloroplasts/images/chloroplastsfigure1.jpg
Photosynthesis in Two Steps : Light Reactions and the Calvin Cycle
Taking a quick review of the earlier equation: Carbon Dioxide + Water --> Sugar + Oxygen. This is actually condensed from two equations, coming from the two ends of photosynthesis: Light Reactions and Calvin Cycle
1. Light Reactions - Uses Light energy to recharge molecules.
Water + Energy-poor Molecules+ Light -> Oxygen + Energy-RICH Molecules
2. Calvin Cycle - Uses those energy-charged molecules to power the creation of a sugar.
Carbon Dioxide + Energy-RICH Molecules ---> Sugar + Energy-poor Molecules
Put those two equations together....
Water + Energy-poor Molecules +Carbon Dioxide + Energy-RICH Molecules + Light --->
Oxygen + Energy-RICH Molecules + Sugar + Energy-poor Molecules
Now, because the energy-poor/rich molecules are present on both sides of the equation, they can be taken out to provide a net result of:
Carbon Dioxide + Water + Light ---> Sugar + Oxygen
As shown above, photosynthesis is the products of Light Reactions and the Calvin Cycle working together. The sugars produced can be used immediatley or stored for long periods of time. When those sugars are stored for a long amount of time in plants, it is referred to as starch.
In Conclusion
The process of photosynthesis is perhaps the most important aspect of life on Earth. This could not be emphasized enough. All energy consumed by non-photosynthetic beings can be traced to something able to perform photosynthesis, whether it is a plant or something else. Finally, there is one more end to photosynthesis. Due to one of the products of photosynthesis is sugar. There is another process called Cellular Respiration, which consists of breaking down that sugar to create Energy-Rich Molecules to power jobs within the cell.
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