Chemiosmosis - Video Tutorials & Practice Problems
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Chemiosmosis
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Video transcript
In this video we're going to discuss chemiosmosis. And so recall from our previous lesson videos that the electron transport chain builds a hydrogen ion concentration gradient. And so that hydrogen ion concentration gradient that's built by the electron transport chain actually has tremendous potential energy. And that potential energy can be captured via the process that's called chemiosmosis. And so, in the word chemiosmosis, you'll find embedded within it the word osmosis, which recall from our previous lesson videos is just referring to the diffusion of water across a semipermeable membrane. And so when we add the word or the prefix chemi in front of it, it's just referring to chemicals that are undergoing osmosis essentially. And so chemiosmosis is the diffusion of chemicals or ions across a semipermeable membrane down their concentration gradient from an area of high concentration to an area of low concentration. And so chemiosmosis is going to be facilitated by an enzyme that's called ATP synthase. And so when you see ATP synthase, notice that it ends in the word the letters a s e, and, because it ends in the letters a s e, we know that it is an enzyme. And so it actually is an enzyme that synthesizes or builds ATP. And so ATP Synthase is an enzyme that facilitates chemiosmosis and synthesizes ATP or energy for the cell. And the ATP synthase is ultimately carrying out the process of oxidative phosphorylation, which once again utilizes the electron transport chain, redox reactions to build a Hydrogen ion concentration gradient, and chemiosmosis which takes advantage of that Hydrogen ion concentration gradient to power phosphorylation and make once again lots of ATP. And so if we take a look at our example down below we can get a better understanding of chemiosmosis. And so notice over here on the left hand side what we're showing you is the same image from our previous lesson video of the Electron Transport Chain. And so once again, the Electron Transport Chain is going to receive electrons from the electron carriers NADH and FADH 2, and these electrons are going to undergo many redox reactions in the electron transport chain, and ultimately end up on oxygen gas which reacts to form water. And as these electrons make their way through the electron transport chain they power the movement of hydrogen ions into the inter membrane space. And so the electron transport chain ultimately is going to build a hydrogen ion concentration gradient. And so here in this video we're focusing in on the process of chemiosmosis, which is really this process over here on the right hand side. And so now that the electron transport chain has built this hydrogen ion concentration gradient that has high hydrogen ion concentration in the intermembrane space and lower, hydrogen ion concentration in the mitochondrial matrix, notice that this enzyme that's embedded in the, inner mitochondrial membrane, is called an ATP synthase. And so, this blue enzyme, this ATP synthase is going to allow for hydrogen ions to diffuse down their concentration gradient in this direction, and that diffusion of the ions down their concentration gradient is ultimately going to power the phosphorylation of ADP into ATP. And so ultimately, this ATP is gonna be created by the process oxidative phosphorylation. And so here notice that this ATP that's being made is being created by oxidative phosphorylation, and recall oxidative phosphorylation is going to create the vast majority of the ATP associated with aerobic cellular respiration. And so ultimately oxidative phosphorylation is going to be the cumulative sum of the electron transport chain building the hydrogen ion concentration gradient, and chemiosmosis, which, utilizes hydrogen ions diffusing across the membrane, and that ultimately is going to power, oxidative phosphorylation. And so this here concludes our introduction to chemiosmosis and we'll be able to get some practice applying the concepts that we've learned here as we move forward in our course. So I'll see you all in our next video.
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Problem
Problem
Chemiosmotic creation of ATP is driven by:
a) Phosphate transfer through the plasma membrane.
b) Potential energy of the H+ concentration gradient created by the electron transport chain.
c) Substrate-level phosphorylation in the mitochondrial matrix.
d) Large quantities of ADP in the mitochondrial matrix.
A
Phosphate transfer through the plasma membrane.
B
Potential energy of the H+ concentration gradient created by the electron transport chain.
C
Substrate-level phosphorylation in the mitochondrial matrix.
D
Large quantities of ADP in the mitochondrial matrix.
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Problem
Problem
The electron transport chain pumps H+ ions into which location of the mitochondria?
a) Mitochondrial intermembrane space.
b) Mitochondrial matrix.
c) Mitochondrial inner membrane.
d) The H+ ions are pumped out of the mitochondria.