Determining the exact yield of ATP for aerobic respiration is difficult for a number of reasons. In addition to generating ATP by oxidative phosphorylation in prokaryotic cells, proton motive force is also used for functions such as transporting materials across membranes and rotating flagella.
And so, of course, maybe the question we should really be asking is how many protons does it take, or how many protons need to flow through this ATP synthase to phosphorylate one molecule of ADP into ATP, and so, I'm actually gonna go ahead back to our ratios up here and write up here that if we knew how many protons were necessary to produce one molecule of ATP, we would be able to calculate essentially the ratio of ATP to NADH or FADH two.
And it's this calculation that I think researchers are actually still trying to, you know, nail down and, you know, I'm sure depending on the type of cell and the state of the cells, the efficiency of this process is going to be different and might, you know, change moment to moment and so, maybe the expectation to have an exact number is not realistic, but researchers are pretty confident with the number, right now, currently of four protons being necessary to produce one molecule of ATP, so, I'm gonna go ahead and just write that in here.
So, remember, that even though it's kind of funky that we're talking about kind of two and a half ATP per molecule of NADH or per molecule of FADH two, really, what this is alluding to is the role of this chemi-osmotic coupling, or using the proton gradient to fuel to ATP synthase and because we're talking about protons now, we need to factor in that, we end up getting these non whole number ratios between ATP and NADH or FADH two.
But with these ratios in mind, I actually wanna go ahead and calculate kinda the sum total of ATP that we produce in cellular respiration, so I've already gone ahead and kinda created a table here, and remember that we're talking about one cycle of cellular respiration, so, as a total ATP yield, let's say per one molecule of glucose, remember. And six NADH times two point five is going to yield And two FADH two times one point five is going to yield three.
And so, if we add all of this up, we get 32 ATP. Now, before I call it good, I wanna make one more last nitpicky point which is to realize that glycolysis, remember, takes place in the cytosol, so unlike the oxidation of pyruvate and the Krebs cycle, which take place in the mitochondria, the NADH that's produced in the glycolysis must actually be shuttled somehow into the inner mitochondrial membrane in order to donate its electrons into the electron transport chain.
But for some reason, it turns out that the inner mitochondrial membrane is actually not permeable to this molecule NADH. So, the body has actually come up with something called shuttle transport systems to shuttle this NADH into the mitochondria.
And it turns out that depending on where the NADH is shuttled into the electron transport chain, so if we actually go back to our diagram here, some of the electrons from the NADH produced in glycolysis can be shuttled into the first electron, first protein complex, and some of them are actually shuttled into this third protein complex here.
And so, depending on whether it's, you know, shuttled earlier later on in the electron transport chain, a different number of protons will be pumped into the proton gradient, remember. And so, the conversion factor for the amount of ATP produced is gonna be different depending on which shuttle is used. Cell Respiration 9. Photosynthesis 3: Genetics 1. Genes 2.
Chromosomes 3. Meiosis 4. Inheritance 5. Genetic Modification 4: Ecology 1. Energy Flow 3. Carbon Cycling 4. Climate Change 5: Evolution 1. Evolution Evidence 2. Natural Selection 3. Classification 4. Cladistics 6: Human Physiology 1. Digestion 2. It gives them the energy they need for the short-term, intense activity of this sport. Aerobic vs. Advantages of Aerobic Respiration A major advantage of aerobic respiration is the amount of energy it releases. Advantages of Anaerobic Respiration One advantage of anaerobic respiration is obvious.
Summary Aerobic respiration produces much more ATP than anaerobic respiration. Anaerobic respiration occurs more quickly than aerobic respiration. Explore More Use this resource to answer the questions that follow. What is the significance of oxygen during cellular respiration?
Which is more efficient: aerobic or anaerobic respiration?
0コメント