Week 4: Oxidative Phosphorylation

Question 1

How is NAD+ regenerated?

Answer 1

The ETC!

Question 2

Complex 1 of the ETC AKA

Answer 2

NADH dehydrogenase

Question 3

NADH Dehydrogenase AKA

Answer 3

NADH DH

Question 4

ETC Step 1 Reaction

Answer 4

*Complex 1*

NADH Fe3+ -NADH DH-> NAD+ + Fe2+

The energy given off by this reaction is used to drive 4 H+ across to the outer mitochondrial matrix

Question 5

ETC Step 2 Reaction

Answer 5

Coenzyme Q carries the electrons from complex 1 to complex 3

Coenzyme Q + e- + Fe3+ -Complex III-> Fe2+ + Coenzyme Q

The energy released from this redox reaction is used to pump 2 more H+

Question 6

Where is the ETC complex 2

Answer 6

It was a misnomer, it is actually succinate DH which is membrane-bound

BUT

FADH2 produced by succinate DH is transferred directly to Coenzyme Q

Question 7

ETC Step 3 Reaction

Answer 7

e- from Complex 3 transferred to the iron in cytochrome C Fe3+ -> Fe2+ and cytochrome C carries the e- to complex IV

O2 + e- -> H2O

*cytochrome c iron can transition between Fe3+ and Fe2+* *heme iron stays as Fe2+*

Pumps 4 more H+

Question 8

What is the goal of ETC

Answer 8

Create a H+ gradient AKA (Proton Motive Force) which is an electrochemical gradient which is both concentration and charge to drive pyruvate into the mitochondria and to drive ATP synthase

Question 9

ATP synthase Reaction

Answer 9

3H+ ADP + Pi -ATP Synthase-> ATP + 3H+

Question 10

How do we get enough Pi into the inner mitochondrial matrix

Answer 10

Pi H+ symporter

Question 11

How do we get enough ADP into the inner mitochondrial matrix

Answer 11

ATP ADP antiporter

ATP out and ADP in

Takes advantage of concentrations of ADP to ATP in the cytosol and mitochondria as well as the charge differential of the ADP (3-) and ATP (4-) takes advantage of positive charge on the outer mitochondrial matrix due to the excess protons