What is the effect of proton accumulation in the intermembrane space?

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Accepted Answer

Hi everybody. Welcome back. The next problem we have says, choose the incorrect statement about the effects of the accumulation of protons in the inter membrane space of mitochondria. A it creates a proton gradient that drives a TB synthesis. B it generates a membrane potential across the inter mitochondrial membrane C. It contributes to the generation of heat in some tissues or d it decreases the ph of the mitochondrial matrix. So before we can answer this, we need to really remember where these different places are and what processes are going on in the different places. So we'll draw our inner mitochondrial membrane. So this is this double layer here. I'm going to give it sort of a yellow highlighting to show that's the membrane and then our outer mitochondrial membrane color yellow again. And so let's label this inner and outer membrane. So the inter membrane space is very obviously between those two membranes and then there's also the mitochondrial matrix surrounded by the inner membrane. Now, what's going on with the flow of protons and the concentration of protons? Well, recall that in our inner mitochondrial membrane, we have our electron transport chain just a series of ovals there. What do IETC? And then we also have a TP synthese, ignore my lovely drawings here. A TP synthesis and we call it our electron transport chain is pumping protons. So we've got some protons in the matrix and the energy uh the electrons going down the electron transport chain allows protons to be transported into the inter membrane space against their concentration gradient. So that means the inter membrane space has a high proton concentration went off the screen there. So the proton concentration is high in the inter membrane space, proton concentration is lower in the mitochondrial matrix. And then a TB synthese has protons flowing down the concentration gradient. And that energy is being used to synthesize a TP. So with that in mind, let's look at our answer choices knowing that we are looking for the incorrect statement. So it's always a little tricky to say it creates a proton gradient that drives a PP synthesis. Well, this is true since we know we have high proton concentration in intramembrane space low in the mitochondrial matrix. And that gradient is what allows the synthesis of a TP. So choice A is a correct statement and therefore can't be our answer. Choice. B it generates a membrane potential across the inner mitochondrial membrane. This is also true. I'm actually going to change that true. The tea I wrote for true to a red to remember that's incorrect. So this is also true. We have a membrane potential because of the charge difference. So due to the charge differential, we have more protons in inter membrane space. So it's more positive in the inter membrane space then in the matrix. So choice B cannot be our answer. How about choice C? It contributes to the generation of heat in some tissues. But we didn't put that in our diagram. But this is also a true statement when the body temperature drops in certain tissues, particularly brown fat, right brown fat, there is a pathway that bypasses a TP synthese allowing protons essentially to leak back into the mitochondrial matrix. And as these protons flow back down with their concentration gradient, decreasing the proton concentration in inter membrane space, this dissipates the proton gradient as heat. So instead of using that energy to generate a TP, the energy is instead used to generate heat when body temperature drops. So that is a true statement and therefore not our answer. So just by the process of elimination, we have choice D as our answer. But let's look at this. It says it decreases the ph of the mitochondrial matrix. Well, the mitochondrial matrix has a low or lower proton gradient due to the protons being pumped and accumulating the inter membrane space, which means that it will increase the ph of the mitochondrial matrix. So our incorrect statement about the effects of the accumulation of protons in the inter membrane space of mitochondria is choice d it decreases the PH of the mitochondrial matrix. See you in the next video.

What is the effect of proton accumulation in the intermembrane space?

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Key Concepts

Proton Accumulation

Intermembrane Space

ATP Synthesis