Source: Video and Images Created by Amanda Soderlind
Welcome to this lesson, an overview of ATP production. Today we will be discussing the processes that occur in cellular respiration in order to produce ATP for a cell.
So, as I mentioned, cellular respiration is the process in which ATP is produced. And ATP stands for adenosine triphosphate, which is basically just an energy storage molecule used by cells.
So in this process organic molecules, which are molecules that contain carbon, are broken down to produce ATP energy. And ATP is the main source of energy used by cells. So substances or organic molecules, such as glucose, lipids, and proteins, can be broken down to make ATP.
But the most important one we're going to focus on is glucose. Glucose produces the most ATP. And extra steps have to happen in order for lipids and proteins to produce ATP. So we will be focusing in this lesson on glucose being used to produce ATP.
So there are three stages to cellular respiration, glycolysis, the Krebs cycle, and the electron transport chain. So we're going to explain what has to happen in each of these stages for ATP to be produced just briefly today.
So the first thing that happens is a glucose molecule will enter the first stage of cellular respiration, which is glycolysis. So glycolysis, as we mentioned, is the first stage in cellular respiration.
And glycolysis occurs in the cytoplasm of the cell. And it's an anaerobic process, meaning that it does not require oxygen for it to occur. OK. So from glycolysis we'll have some products produced that will be transferred into our other stages of cellular respiration.
So our next stage of cellular respiration is the Krebs cycle. This says Krebs cycle. So that's our second stage of cellular respiration, which occurs in the mitochondria of the cell.
So this structure right here is our mitochondria. So that's a cellular organelle found within our cells. And it occurs in the inner membrane of the mitochondria.
So we have glycolysis followed by the Krebs cycle. And the Krebs cycle is an aerobic process, which means it needs oxygen for it to occur. And then some of our products from the Krebs cycle will then be transferred into our next stage, which is the electron transport chain.
And I'll do this with a darker color. And I'm going to abbreviate the electron transport chain as ETC, electron transport chain. So this is our third stage in cellular respiration.
And this also, as you can see, is occurring in the inner compartment of the mitochondria. And it's also an aerobic process which requires oxygen to occur.
So at the end of all of this what we end up with is 36 ATP molecules. So through all three of these stages in the very end we end up with a net gain of 36 ATP molecules for every one glucose molecule that entered the process. And each of these different stages produces some ATP, but the vast majority of our ATP is produced in the electron transport chain.
And just to give you a brief idea of what ATP looks like, ATP is actually a nucleotide. So I'm just going to draw the quick structure here of what an ATP nucleotide looks like. OK.
So a nucleotide contains a type of sugar. We have a ribose sugar attached to our base, which is adenine. And then it also is attached to three phosphates. OK. So these are all phosphates.
And our energy is actually stored here in the bond between our extra phosphate. So ATP can give away or take on extra phosphates. And when it has that extra phosphate on it, it's actually stored energy right there.
So that's where we're storing our energy in ATP. So ATP is a nucleotide with this structure here. So this lesson has been an overview on the processes that occur for ATP to be produced by a cell.