Chapter Population Genetics. Chapter Evolutionary History. Chapter Plant Structure, Growth, and Nutrition. Chapter Plant Reproduction. Chapter Plant Responses to the Environment.
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Thank You. Please enjoy a free hour trial. When glucose is in adequate supply, such as shortly after consumption of a meal, the hormone insulin from the pancreas increases glycogen formation glycogenesis in the liver.
When glucose levels drop between meals, the hormone glucagon is released from the pancreas and stimulates the conversion of glycogen into glucose by the process of glycogenolysis. If all glycogen supplies are depleted, then other substances in the body are converted into glucose or intermediate products that can enter the above-outlined cellular respiration pathway.
The conversion of fatty acids from lipids or amino acids from proteins into glucose or intermediate products is called gluconeogenesis p. Fats lipids are stored in adipose tissue. Where do organisms get energy from? What is ATP? When the covalent bond between the terminal phosphate group and the middle phosphate group breaks, energy is released which is used by the cells to do work.
What Is Cellular Respiration? The process begins with Glycolysis. In this first step, a molecule of glucose, which has six carbon atoms, is split into two three-carbon molecules. The three-carbon molecule is called pyruvate. Pyruvate is oxidized and converted into Acetyl CoA. These two steps occur in the cytoplasm of the cell. Acetyl CoA enters into the matrix of mitochondria, where it is fully oxidized into Carbon Dioxide via the Krebs cycle.
Finally, During the process of oxidative phosphorylation, the electrons extracted from food move down the electron transport chain in the inner membrane of the mitochondrion.
As the electrons move down the ETC and finally to oxygen, they lose energy. Glycolysis The first stage of cellular respiration is glycolysis. Results of Glycolysis Energy is needed at the start of glycolysis to split the glucose molecule into two pyruvate molecules. Transformation of Pyruvate into Acetyl-CoA In eukaryotic cells, the pyruvate molecules produced at the end of glycolysis are transported into mitochondria, which are sites of cellular respiration.
Citric Acid Cycle Before you read about the last two stages of cellular respiration, you need to review the structure of the mitochondrion, where these two stages take place.
The space inside the inner membrane is full of fluid, enzymes, ribosomes, and mitochondrial DNA. This space is called a matrix. The inner membrane has a larger surface area as compared to the outer membrane.
Therefore, it creases. The extensions of the creases are called cristae. The space between the outer and inner membrane is called intermembrane space. Through a series of steps, citrate is oxidized, releasing two carbon dioxide molecules for each acetyl group fed into the cycle. Because the final product of the citric acid cycle is also the first reactant, the cycle runs continuously in the presence of sufficient reactants. Results of the Citric Acid Cycle After the second turn through the Citric Acid Cycle, the original glucose molecule has been broken down completely.
Oxidative phosphorylation Oxidative phosphorylation is the final stage of aerobic cellular respiration. Chemiosmosis The pumping of hydrogen ions across the inner membrane creates a greater concentration of these ions in the intermembrane space than in the matrix — producing an electrochemical gradient. How Much ATP?
Review What is the purpose of cellular respiration? Provide a concise summary of the process. State what happens during glycolysis. Describe the structure of a mitochondrion. Outline the steps of the Krebs cycle. 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.
So, I just wanna make that point and have you be aware of the fact that this number right here, this number here is actually a range, it can actually range from anywhere to three to five ATP produced per molecule of NADH.
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