What is the pH in the mitochondrial matrix and why?

[Gauss44]

...as in the general pH, like acidic, basic, or neutral...

inner membrane space = acidic, lots of H+ ions
inner membrane = basic, electron transport chain
matrix = ???

And where does the oxygen that binds to hydrogen at the end of the electron transport chain come from?

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[Patassa]

...as in the general pH, like acidic, basic, or neutral...

inner membrane space = acidic, lots of H+ ions
inner membrane = basic, electron transport chain
matrix = ???

And where does the oxygen that binds to hydrogen at the end of the electron transport chain come from?

Why would the inner membrane be basic, it's just a bunch of hydrocarbons mostly isn't it?

 

[QrtrLifeCrisis]

...as in the general pH, like acidic, basic, or neutral...

inner membrane space = acidic, lots of H+ ions
inner membrane = basic, electron transport chain
matrix = ???

And where does the oxygen that binds to hydrogen at the end of the electron transport chain come from?

All you have to know is that the inner membrane space is acidic relative to the matrix because H+ has to flow down ATP synthase to generate ATP. I would not worry about the actual pH numbers.

The oxygen passively diffuses in from the environment because O2 is nonpolar.

 

[Gauss44]

All you have to know is that the inner membrane space is acidic relative to the matrix because H+ has to flow down ATP synthase to generate ATP. I would not worry about the actual pH numbers.

The oxygen passively diffuses in from the environment because O2 is nonpolar.

I'm just interested in why the matrix it's basic, if it's basic. Do you know?

 

[Gauss44]

Why would the inner membrane be basic, it's just a bunch of hydrocarbons mostly isn't it?

Because of all the electrons in the electron transport chain. Do you disagree?

 

[rguil15]

Because of all the electrons in the electron transport chain. Do you disagree?

Ok my biochem text book says that the difference in pH between the matrix and the intermembrane space is .75 units. How's that for an answer, ha. So one is more acidic or basic relative than the other, but neither is going to be acidic or basic on some absolute scale I wouldn't think because then you'd start running into problems with your proteins.

Also the O2 is bound to heme a3 in the IV subunit.

 

[Patassa]

Because of all the electrons in the electron transport chain. Do you disagree?

Well, the electrons aren't going to change the pH of something plus they are interacting with the proteins in the membrane in specific areas of the membrane. I would say the membrane itself is neutral.

 

[DocForP]

Just to sum up what everyone has said so far.

The reason why the matrix is basic is because the electron transport chain is creating a gradient of H+ in regards to the matrix and the outside of the inner membrane of the mitochondria. The ATP formation is driven by H+ flowing down its concentration gradient, which means that the outside concentration of H+ has to be higher than the matrix in order for that to occur. Thus, higher H+ outside constitutes lower (acidic) pH in comparison to the more basic matrix because of ETC activities.

 

[Gauss44]

Ok my biochem text book says that the difference in pH between the matrix and the intermembrane space is .75 units. How's that for an answer, ha. So one is more acidic or basic relative than the other, but neither is going to be acidic or basic on some absolute scale I wouldn't think because then you'd start running into problems with your proteins.

Also the O2 is bound to heme a3 in the IV subunit.

This sounds VERY helpful (esp. since it's from a biochem book). One point I'm confused about: Did they definitely say, "intermembrane space" and not "inner membrane?"

I thought, perhaps inaccurately, that the innermembrane space was full of H+ ions, and that the matrix was suppose to be negatively charged.

 

[Gauss44]

Well, the electrons aren't going to change the pH of something plus they are interacting with the proteins in the membrane in specific areas of the membrane. I would say the membrane itself is neutral.

A good point. I should have said, "negatively charged" instead of "basic." And that would apply to electrons flowing through the membrane, not the membrane itself.

 

[Patassa]

This sounds VERY helpful (esp. since it's from a biochem book). One point I'm confused about: Did they definitely say, "intermembrane space" and not "inner membrane?"

I thought, perhaps inaccurately, that the innermembrane space was full of H+ ions, and that the matrix was suppose to be negatively charged.

They are using inter-membrane space as a synonym for inner membrane space.

By process of elimination I guess they would have to use "intra-membrane" to talk about anything happening in the actual membrane itself.

The full sentence from the text is as follows, "In actively respiring mitochondria....the pH of the matrix is about .75 units more alkaline than that of the intermembrane space."