Photosynthesis in plants and a few bacteria is responsible for feeding nearly all life on Earth. It allows energy from the sun to be converted into a storable form, usually glucose, which plants use to grow. Photosynthesis also generates the oxygen that animals need to survive. We exhale the carbon dioxide that plants need for photosynthesis. Also, photosynthesis requires sunlight, water, and carbon dioxide to occur, and create ATP. ATP is a chemical created by plant and animal cells to create energy for the cells.
Photosynthesis can be broken down into two separate parts, the Light Reaction, and the Dark Reactions, or the Calvin Cycle. Let’s start with a basic rundown of photosynthesis. we start off with photons and water and carbon dioxide, and we use that energy in the photons to fix the carbon. And now, this idea of carbon fixation is essentially taking carbon in the gaseous form, in this case carbon dioxide, and fixing it into a solid structure. And that solid structure we fix it into is a carbohydrate. The first end-product of photosynthesis was this 3-carbon chain, this glyceraldehyde 3-phosphate. But then you can use that to build up glucose or any other carbohydrate.
Now, that we have a basic understanding of photosynthesis, let’s go deeper into the rabbit hole. The light cycle is started way down in a plant cell. In that plant cell are ten to fifty chloroplasts, and in those chloroplasts a thylakoids. These thylakoids are like mini pancakes just stacked on top of each other to create a grana within a chloroplast, inside a plant cell, in a plant. Now, let’s zoom in again to the thylakoid membrane. On one side of the membrane there is the liquid that fills the thylakoid, lumen, and on the other side is the liquid that fills the chloroplast. In the membrane are little photosystems, however, they are way too complex to go in depth. You got that? I hope you do, because we’re now going to go through the actual process of photosynthesis. You have some photons.
Photons from the sun. so you have some photons that go here and they excite electrons in a chlorophyll molecule, in a chlorophyll molecule. They enter into a high energy state. And then as they go from molecule to molecule they keep going down in energy state. But as they go down in energy state, you have hydrogen protons without the electrons. So you have all of these hydrogen protons. Hydrogen protons get pumped into the lumen. Now that you have the hydrogen protons in the lumen, that concentration of hydrogen protons is used to drive ATP synthase, which I really don’t want to get into, so we’ll settle for this.