AAMC Sample Test B/B #16

[xoxo111]

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I thought cytochrome c carries 2 electrons since NADH-->NAD + H + 2e; therefore shouldn't the answer be B?

 

[Hi_I'mPaul]

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I thought cytochrome c carries 2 electrons since NADH-->NAD + H + 2e; therefore shouldn't the answer be B?

Are you thinking of ubiquinone (Q)? Because Cytochrome C transfers electrons (only one at a time) from complex 3->4. Ubiquinone transfers electrons (2) from complex 1->3 and 2->3! Hope this helps ~

 

[Hi_I'mPaul]

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No not ubiquinone because even google says that cytochrome c carries 2 electrons?...

Read that closely, my friend. It says cytochrome c transfers 1 electron while ubiquinone transfers 2

 

[xoxo111]

Read that closely, my friend. It says cytochrome c transfers 1 electron while ubiquinone transfers 2

Oh yeah...

 

[aldol16]

I know chemistry isn't exactly a pre-med's favorite subject but it's helpful in this case because it'll tell you exactly what you need to know. What is cyt c? It's a metalloenzyme. The important part is that it carries an iron that alternates between the ferrous (+2) and ferric (+3) states which is what it uses to carry electrons. Again, ferrous and ferric. These are the oxidation states that iron is typically in in nature. So that's why it can only carry one electron at a time. Going from ferric to iron(I) is not favorable.