NAD+

[dentistguinness]

What is NAD+? Where does it come from and how does it make NADH?

---

Members don't see this ad.

 

[Ant951]

Also to add on if you are wondering about NAD+ still, it is utilized in both glycolysis and the TCA cycle and generates NADH which can further be utilized in the ETC to generate ATP. NAD+ is regenerated by fermentation. If you want the specifics, just check up on the enzymes, but I do not believe you need to know that for the DAT.

 

[Lunatic]

NAD+ is a biological compound that can be reduced in a redox reaction to form NADH. It is an electron carrier used for electrochemical gradients. NADH is the reduced form of NAD+ and has energy potential. In a redox reaction, it is oxidized into NAD+.

In analogous terms, think of NAD+ as a drained battery and NADH as a charged battery. The movement of electrons as a charged battery drains can provide energy to do work.

Glycolysis and the TCA cycle charges up NAD+ to NADH. Then it is oxidized (drained of electrons) in the electron transport chain. The work this process does is that it creates a proton gradient and ATP synthase dissipates this gradient in a way that gives energy to make ATP.

Many students find this topic difficult. But if you spend some time thinking about it and come to recognize that it's not some foreign process, you'll see how logical and beautiful the system is.

 

[dentistguinness]

Why is there only one (for 1 cycle) FAD -> FADH reaction in Krebs when there are three NAD+ -> NADH? Why does the Krebs cycle only deal with vitamin B? What about other organic molecules/coenzyme? Sorry if this doesn't make sense, I just looked up FADH and NADH and it said it had something to do with riboflavin and vitamin B so I'm having a "coincidence i think not" moment.

 

[Lunatic]

Why does the earth rotate every 24 hours?
Why does the sun rise from
the east? Why did the India subcontinent crash into Asia millions of years ago? Why did it take 6 seasons for winter to finally arrive in Westeros? Why is ATP the the main energy currency and not UTP or TTP? Probably because events aligned millions/billions of years ago that resulted in these outcomes.

Why does the Kreb cycle reduce 3 NAD+ and 1 FAD? Most likely because the system happened to develop like this in some ancient microorganism and it worked well enough to stick around.

The specific reason why FAD is reduced instead of NAD+ in one step of the cycle is because that step is only exergonic to the degree that would allow FADH2 to be made
(FAD is a smaller battery than NAD+ so it's easier to reduce FAD).

There are several B vitamins. Thiamine is involved in pyruvate decarboxylation. Riboflavin is a part of FAD/H2. Niacin is a part of NAD+/H.

Most likely everything I said is above the scope of the DAT. If you're interested you should take a biochemistry course.