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11. Biological Membranes and Transport

SERCA: Calcium Ion Pump



SERCA: Calcium Ion Pump

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So now that we've covered the sodium potassium 80 p ace in this video, we're going to introduce yet another example of a P type 80 p ace, which is the circa pump, which is really just a calcium ion pump as we'll see here very shortly. Now, circa is really just an abbreviation for Sarko Plas, Mick or Endo Plasvic, Ridiculous calcium, A TPS and circa, really functions as a uni porter, which will see down below in our image. But recall from our previous lesson videos that uni porters will pump just one type of molecule across the membrane in one direction. And in this scenario, circa is pumping calcium ions or see a two plus into either the Sarka Plasvic ridiculous, Um, s are or Endo Plasvic Ridiculous e r. Depending on the cell type. And of course, if it's constantly pumping calcium into the S r E. R, it's gonna be keeping the cytoplasmic calcium concentrations really, really low, and that's going to be very important for many different cell functions. And so, if we take a look at our image down below of the circa pump, noticed that going across the top here, what we have is the cells plasma membrane, which is separating the extra cellular space here in blue from the inside of the cell or the cell cytoplasm. And notice that in the cytoplasm here, what we're showing you are to calcium ions so we could go ahead and label these as calcium ions and notice that below those calcium ions, we have another membrane here which is the Sarko Plasmid particular membrane, or endo plasvic particular membrane, depending again on the cell type and notice that embedded in this S r or er membrane. What we have is the circa pump that were introducing here and again. The circa pump is a classic example of a p type a TPS, which means that it's going to get fuss for elated at some point to create a fuss for related intermediate and so you can see that down below it is utilizing a teepee and hide relies ing 80 p into a d. P. And in that process, the circle pump is actually getting phosphor elated itself. And so you can fill in the P here on the representing the Fosse to show that circa pump is AP type DPS and as it gets Foss for elated. What it will do is actually take to calcium ions as we see here, and it will pump these two calcium ions from the cytoplasm and pump them into the S R or E R. And so you should draw in this blue arrow here to remind you guys that calcium is getting pumped from the cytoplasm into the S r er in order to keep cytoplasmic calcium concentrations really, really low. And so what's really important to note here is that when released into the cytoplasm, calcium actually has a very important role and pretty much all cells. And that's because they can act as an interest cellular signal in virtually all cells. And later in our course, when we're talking about bio signaling, we'll be able to talk about some specific pathways bio signaling pathways that utilize calcium as an interest cellular signal. But you might also recall, in our previous lesson videos that we talked a little bit about muscle contractions and so recall that muscle contractions will actually occur when a nerve impulse induces the release of calcium into the cytoplasm. And so you can see over here we have another pump embedded in the membrane that is utilized to release calcium into the cytoplasm. And when calcium is in the cytoplasm again, it acts as an inter cellular signal and can induce muscle contractions. And so you can see the calcium here can induce a muscle contraction. And, of course, ah, muscle contraction is going to occur When, uh, there is, uh, this increase of cytoplasmic calcium concentration, and so muscle contractions are associated with increasing cytoplasmic concentrations of calcium. Now, of course, we know that circa the pump over here is all about decreasing calcium concentrations in the cytoplasm. And so the circle pump will again pump calcium into the S R E r. And so when it does that, it's actually going to allow for muscle relaxation to occur. And so it will occur when circa pumps calcium into the S r E are decreasing the, uh, cytoplasmic concentrations of calcium. And so here what we're saying is that increasing cytoplasmic calcium concentration leads to muscle contraction, whereas decreasing cytoplasmic calcium concentration leads to muscle relaxation, and again, that is what circa is gonna be helping with. And so this year concludes our introduction to these circa calcium ion pump. And as we move forward in our course, we'll be able to get some practice applying these concepts that we've learned. So I'll see you guys in our next video.

The calcium ATPase is an example of what type of transport model?


The calcium ATPase (SERCA) _____________________: