Electron carriers capacities

[Haiba]

Hello everyone,

I was wondering if anyone can help me on the numbers of electrons that the carriers (NAD, FAD, cyochrome c, etc)in the electron transport chain can carry? I remember from taking biochem class that some accept one and some accepts two electrons but I can't remember which is which. I'm also confused because the KA video shows that FAD accepts 2 hydrogens compared to NAD that accepts 1 hydrogen but both are shown to accept 2 electrons so if they are all accepting 2 electons which one accepts only one as I learned in my class? I've looked online but couldn't find the answer that relieves my confusion, so really if you can answer me or provide a link, I would appreciate it.

Thank you!

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[theonlytycrane]

When you say NAD+ accepts 1 hydrogen, it's actually a hydride nucleophile with 2 electrons that it's accepting.

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NAD+ accepts and delivers 2 electrons at a time.

FAD can accept 1 or 2 electrons at a time, but to simplify just think of this as 2 electrons being transferred as in the ETC to complex II.

UQ carries 2 electrons from complexes 1 and 2 to complex III. It can also carry 1 electron at a time.

Cytochrome c transfers 1 electron at a time between complexes III and IV.

 

[Haiba]

OMG!! This is sooo nicely written and informative
Thank you SO MUCH!
I finally get it!

 

[aldol16]

I was wondering if anyone can help me on the numbers of electrons that the carriers (NAD, FAD, cyochrome c, etc)in the electron transport chain can carry? I remember from taking biochem class that some accept one and some accepts two electrons but I can't remember which is which. I'm also confused because the KA video shows that FAD accepts 2 hydrogens compared to NAD that accepts 1 hydrogen but both are shown to accept 2 electrons so if they are all accepting 2 electons which one accepts only one as I learned in my class? I've looked online but couldn't find the answer that relieves my confusion, so really if you can answer me or provide a link, I would appreciate it.

There is still ambiguity about FAD's mechanism of action - it appears that it does different things in different locations and so that's why it can accept one or two electrons (each via a different mechanism). Cyt c must only be able to carry 1 electron because it works using a metal center, which is only reduced up or down one unit. After reduction by one unit, the redox potential of the iron is much lowered. Similarly with the Fe-S clusters that carry electrons one at a time.

 

[Haiba]

ohhh I see! thank you!!

 

[whitesox137]

This might come off odd, but is that the extent to what we need to know about the ETC for the MCAT (knowing how many electrons are transferred at each complex and the names of each complex)? Sorry, my exam is July 9 and am trying to get down the simple aspects of metabolism because memorizing the each individual events of metabolism are a waste of time and energy from what I understand. Please correct me if i am wrong. Thank you.

 

[Haiba]

This might come off odd, but is that the extent to what we need to know about the ETC for the MCAT (knowing how many electrons are transferred at each complex and the names of each complex)? Sorry, my exam is July 9 and am trying to get down the simple aspects of metabolism because memorizing the each individual events of metabolism are a waste of time and energy from what I understand. Please correct me if i am wrong. Thank you.

I'm taking it the same day as you. My studyplan is to read over the metabolisms pathways and know the main parts (where they occur, what's the point of them, do they produce NAD or NADH,).
I also know for example that isocitrate is from Krep. I don't know how we get to that moelucle, but my point is to be able to recognize the enzymes if I see them. This question about e carriers was from my biochem class that I never understood, so I wanted to be clear on that.

For ETC, know that, and know where ETC occurs, know that we go from low reducation potential to high reducation potential (more likelihood of accepting electrons). That was in KA videos so I'm assuming that is what they want us to know.