What is Aerobic Respiration?
Aerobic respiration. Let’s look over here first. In aerobic respiration, step 1 is always glycolysis, and during glycolysis you have 2 pyruvate and 2 ATP molecules that are formed, so that gives you a little bit of energy and the pyruvate to start the rest of the aerobic respiration process.
Step 1, glycolysis where you get the pyruvate and the energy that you need to keep going. The next step is where our pyruvate is converted into 2 acetyl groups that are combined with coenzyme A to form Acetyl CoA, and that’s just an abbreviation letting you know that the acetyl groups combined with coenzyme A.
We got this from pyruvate, which we got from glycolysis, where some glucose was broken down. Let’s keep going. Next, the Acetyl CoA enters the matrix of the mitochondria, where it enters the Krebs cycle. This is also called the citric acid cycle. We’ve got our Acetyl CoA entering the matrix of the mitochondria (this is where it’s going to take place), and then it enters the Krebs cycle.
During the Krebs cycle, 8 additional hydrogen rich NADH molecules, and 2 additional FADH molecules are generated during the Krebs cycle. We’ve broken out our pyruvate into 2 acetyl groups, combined them with coenzyme A, we’ve turned that Acetyl CoA, through the Krebs cycle, into these 8 additional NADH hydrogen rich molecules and the 2 FADH molecules, and now we are going to keep moving them.
In the next step, these are reduced. That’s going to be in the electron transport chain, still in the mitochondria (so, electron transport chain). These are reduced, and the resulting electrons create a proton gradient, and these protons that have been created kind of cascade down the gradient, and as they do that, in ATP synthase, they generate 30 or more molecules of ATP.
Just imagine those protons cascading down, and as they slowly fall down they are generating energy, and it can be 30 or more molecules of ATP that are generated. Let’s look at all of this in a diagram, maybe simplified a little. We’ve got our cell, and nutrients are taken into that cell. In the nutrients were going to get some glucose, and from 1 molecule of glucose we are going to carry out glycolysis and get 2 ATP net energy over here, plus our pyruvate.
All of this happened in the cytoplasm of the cell. We’re inside the cell, but we’re in the cytoplasm. Next, the pyruvate is going to go into the mitochondria (singular mitochondrion), so its just going in this 1 (and its going to keep going), and the Acetyl CoA that we got from the pyruvate is going to go into the matrix of the mitochondria and enter the Krebs cycle.
During the Krebs cycle, were going to get those molecules we talked about, our hydrogen rich NADH and our FADH and they’re going to enter the electron transport chain and as they are reduced, they form that proton gradient, the protons cascade down and generate 30 or more ATP molecules, with some waste particles in the form of H2O (water), and carbon dioxide.
There are some waste products here, but oxygen went in (because this is aerobic respiration), we got 30 plus molecules of ATP, plus the 2 from glycolysis, so a net of 32 total. Now that could differ, because the mitochondria has this membrane around it, and some energy can escape from the membrane, and some energy can escape from the cell, so sometimes you lose some of that energy along the way, but on average you could get 30 to 32 net ATP molecules from 1 molecule of glucose, and then you do have some waste products left over.
This is a really complicated process, hopefully this has simplified it for you, but the primary reason that a cell is going to undergo aerobic respiration, is so it can get a lot of energy and expel some waste products.