What is photosynthesis and how can we easily understand its complicated chemistry?


What is Photosynthesis?

In order to survive, plants must acquire food into their system, similar to animals. Plants take in the carbon dioxide (CO2) that animals give off and give oxygen in return, for us all to use. But, how do the do it?! The short answer is: through . Photo... what?

Photosynthesis is the process by which plants convert energy from the sunlight to create organic molecules (chemical energy) that they use. While plants absorb needed nutrients and water from the ground up through their roots, photosynthesis occurs in the leaves. Hmmm... Let's see how...


Photosynthesis for Dummies (and Kids)

Here's how the entire process of photosynthesis works:

1. First, the molecules of chlorophyll (a green pigment found in almost all plants) contained in the chloroplasts (organelles found in plant cells that conduct photosynthesis) absorb energy in the form of sunlight. Obviously, some plants need more light from the sun than others, but all need at least a little. You see, sunlight plays an important role in the whole photosynthesis formula as you are about to find out.

2. Plants absorb water from underground through their roots and carbon dioxide from the air (instead of taking in oxygen like all animals do). During the process of photosynthesis, the energy received from the sun splits the absorbed water molecules into hydrogen and oxygen. The oxygen molecules are released by the plant into the atmosphere, making life possible for all life forms on Earth.

Meanwhile, molecules of ATP (molecules that provide our bodies with the necessary energy - chemical energy - in order to function) are created within the plant's cell. This process is called "photochemical" or light reaction because it requires light to occur.

photosynthesis for kids

Photosynthesis for Kids
Plants take energy from the sun and turn it into food. This is very nice of the plants because animals can't eat sunshine, can they? Plants then use the sunlight to convert carbon dioxide and water into organic compounds like glucose (that's sugar). This whole process is called photosynthesis. Repeat with me, kids: pho-to-syn-the-sis. Photosynthesis is very important for life on Earth as it provides the oxygen (the air you breathe) on which all life forms depend. Besides, no plants = no animals = no humans.

3. Enzymes (proteins that catalyze or biological catalysts) combine the hydrogen with carbon dioxide to create a carbon compound, also with the help of an intermediate called phosphoglyceraldehyde (PGAL). PGAL goes on into the process of producing glucose (a type of sugar), which all plants use as fuel.

This whole process is called a dark reaction or carbon-fixation reaction (because atoms of carbon are "fixed": they can be found into stable compounds). Don't worry; we'll talk about the basic chemical equation of photosynthesis in just a minute.


Hit *play* to watch the following "Photosynthesis for Dummies" video...
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 Photosynthesis for Kids Video - How plants create food through photosynthesis.

4. When plants create more glucose than they really need to survive, they integrate that glucose into larger carbohydrate molecules called starch. The starch molecules are stored within the large vacuoles (membrane-bound organelles) in the plant cells. The plant will later break down the starch molecules to retrieve glucose just for energy or to create really cool things, such as sugar, proteins or fats. That's pretty much it... Now, let's see the chemical equation of photosynthesis.


The Chemistry of Photosynthesis

Basically, photosynthesis has two different components:

  1. The Light Reaction takes place in sunlight and involves the P680 and P700 photo-systems. This light-dependent reaction has two components as well:

    1. Cyclic Photophosphorylation (produces energy needed for the light reaction)

    2. Non-Cyclic Photophosphorylation (produces NADPH and ATP to be used by the dark reaction)

  2. The Dark Reaction - Also known as the "Calvin Cycle" forms glucose with NADP+ and ADP being recycled back to the light reaction.

This is the chemical formula for photosynthesis:

Light+H2O+CO2+O2+CH2O

H2O=water; CO2=Carbon Dioxide; O2=Oxygen; CH2O=Formaldehyde (a gas)

Real Life Applications of Photosynthesis

The artificial leaf has been a subject of research for years. An artificial leaf is basically an object that creates energy out of sunlight, mimicking plant's photosynthesis. While this seems depicted from a science fiction movie, the researchers from MIT did it! They recently designed an artificial leaf that, when placed in water in sunlight, it uses a cheap catalysts to convert the liquid into, you've guessed, hydrogen and oxygen.

Each gas is emitted from a different side of the leaf thus could be used as a power source. Scientists say that, using this artificial leaf and a gallon (4 liters) of water, they can generate enough power to fuel your house for a day. Currently the device is 10 times more efficient than natural photosynthesis, but the researchers are optimist they can improve it further. Will scientists succeed in further improving the formula for photosynthesis? Also, from where can we buy this miraculous leaf?

Isn't this a wonderful alternative for nuclear power plants that produce waste that stays radioactive for thousands of years and occasionally contaminate our drinking water or could eventually lead to a world? Think about it...


Thank you for reading this article on photosynthesis. Have a very safe and warm day!