Idea of Photosynthesis by Jan Ingenhousz
To begin, the idea of photosynthesis was created by, according to Encyclopaedia Britannica, “”A Dutch scientist, Jan Ingenhousz. (Ingenhousz 1.) He was born in the Netherlands on December 8, 1730. Ingenhousz, is most known for his discovery of photosynthesis. According, to Encyclopedia Britannica, “”Ingenhousz discovered that light is necessary for photosynthesis, only the green parts of the plant perform photosynthesis, and all living parts of the plant can potentially damage the air.”” (Ingenhousz 1.)
Photosynthesis occurs in two steps inside of the chloroplast. First, is the light reactions. This occurs in the disc of the thylakoid. From here, energy light is captured and water is split to create ATP and NADPH. These are energy molecules, that will be used in the next reaction. The light reaction also creates an oxygen byproduct. The ATP and NADPH are used in the dark reaction, which takes carbon dioxide, converting it into glucose. The NADP+ and ATP produced, can be recharged, back at the light reaction in the thylakoid disc.
If you look closer to light reactions, you’s see that the membrane of the thylakoid discs have proteins embedded, which carry out the light reaction. Outside of the thylakoid disc is the stroma, and inside of that is the thylakoid space. Light strikes photosynthesis which are clusters of chlorophyll. This captured light, excited 2 electrons, which are then transferred from one molecule to the next by the electron transport chain, and this is a series of proteins. This process also brings some hydrogen ions into the thylakoid space. Next, and enzyme splits a water molecule releasing oxygen, which diffuses out of the plant. Now there’s only one oxygen atom, but when there’s only one molecule split, two oxygen atoms will form O2.
The hydrogen atoms that produced, are left in the thylakoid space. Light strikes again making the electrons excited, and they load onto an NADP+ with a hydrogen atom to form NADPH. ATP is made using the protons from the water molecules, with the enzyme, ATP synthase. Now it’s time for the dark reactions.
The dark reactions occur in the stroma, the fluid surrounding the thylakoid discs. Dark reactions happen in the presence of light, but it doesn’t need light to occur. This is also known as the Calvin Cycle. In the calvin cycle, 6 carbon dioxide molecules in their atmosphere, along with a good amount of ATP and NADHP+, are converted into a molecule of glucose. It takes 6 turns of the calvin cycle to create glucose, then the plant can use that glucose for energy, or to make cellulose.
Some plants use different variations on the light and dark reactions to make glucose. C4 plants make a 4 carbon compound so that they can partially close their stomata to prevent water loss during the day. The four carbon compound can be converted back to CO2 for the Calvin Cycle, later on. Cam plants open their stomata at night, and close them during the day to conserve water. They have to do this because they live in such hot environments.
Next we transition into cellular respiration. According to ________, “”Cellular respiration were created by, Carl Benda is 1898, and won a Nobel prize for his discovery. (Benda__ .) The cell needs to be able to harvest energy from glucose to get the usable energy, ATP. Whether oxygen is present or not cells can always do glycolysis which occurs in the fluids cytosol of the cell. No oxygen is needed for this. During glycolysis the six carbon glucose molecule is broken in half and rearranged to make two pyruvic acid molecules. The process requires 2 ATP to get started but ultimately it produces four ATP from ADP and phosphate, and it produces 2 NADH from NAD+, so overall glycolysis makes 2 pyruvic acids to ATP and two NADH. From here, there are two possible pathways that could be taken.
Cellular respiration always starts the same way, with glycolysis. From there the two pathways are determined by the presence of oxygen if there is no oxygen available anaerobic respiration will occur, but if oxygen is available aerobic respiration will occur in the mitochondria.
Fermentation is an anaerobic process that converts sugars to acids or gases or alcohols and includes the glycolysis step in it. Fermentation replenishes the supply of energy plus so that glycolysis can continue reading the ETC. Lactic acid fermentation, pyruvic acid is converted to a chemical called lactic acid. The process changes NADH back to NAD+.
Our muscles use lactic acid fermentation when there’s not enough oxygen to do aerobic respiration. Your muscles will feel cramped and painful. But this pain won’t be permanent, as long as you get enough oxygen back to muscles so that you can go back into aerobic respiration. Other organisms use a different pathway and create an alcohol and carbon dioxide instead of lactic acid and pyruvic acid.
If oxygen is present, aerobic respiration occur and it’s an ATP producing machine. Aerobic respiration takes place in the mitochondria of eukaryotic cells, and in the cytosol of prokaryotic cells. After glycolysis occurs in the cytosol and pyruvic acid is attached to coenzyme A, there are two major parts!
The Krebs Cycle and the ETC. During the Krebs cycle, 2 ATP and the gas, carbon dioxide, are produced. The carbon dioxide will eventually diffuse out of the cell. This is why we breathe out carbon dioxide. The final reaction is glucose plus oxygen, yields 6CO2 and 6 water plus energy in the form of ATP. That’s The process of photosynthesis and cellular respiration.