Bio emergency help

OP

Original post by RMNDK

It isn't?
NAD+ is always NAD+ in glycolysis. Think, the charges don't add up on both sides.

so NAD is ALWAYS in its oxidised state?

Reply 4

Original post by z33

so NAD is ALWAYS in its oxidised state?

Not always. It can be reduced to NADH. But it's either one or the other (to the best of my knowledge)

Where did you learn that it's NAD in glycolysis?

Reply 5

OP

Original post by RMNDK

Not always. It can be reduced to NADH. But it's either one or the other (to the best of my knowledge)

Where did you learn that it's NAD in glycolysis?

In the text book for link reaction it says :

" 2pyruvate + 2NAD+ + 2CoA -> 2CO2 + 2redNAD + 2acetyl CoA

NAD+ indicated NAD in the oxidised state"

for glycolysis it doesn't say anything about oxidised state or not but various sources on the internet say various things

some sources even say NAD+ is reduced to NADH + H+ !

should i just put redNAD instead or do i lose marks? (OCR btw)

Reply 6

Original post by z33

In the text book for link reaction it says :

" 2pyruvate + 2NAD+ + 2CoA -> 2CO2 + 2redNAD + 2acetyl CoA

NAD+ indicated NAD in the oxidised state"

for glycolysis it doesn't say anything about oxidised state or not but various sources on the internet say various things

some sources even say NAD+ is reduced to NADH + H+ !

should i just put redNAD instead or do i lose marks? (OCR btw)

That equation is correct, although you could cancel everything by 2...

That source is actually correct. NAD⁺ is reduced to NADH + H⁺. That equation doesn't give the full picture:
NAD⁺+ 2H⁺2e^- --> NADH + H⁺

Two electrons are required to reduce NAD⁺, one for NAD⁺and one for H⁺. However, you only need one H⁺, the other H⁺ acts as an electron carrier which is why its not needed and returns back into the matrix to reduce more NAD⁺. Thus it acts as a catalyst.

I don't know OCR requirements. For AQA, saying reduced NAD or NADH are both fine. I wouldn't think different for OCR.

Reply 7

OP

Original post by RMNDK

That equation is correct, although you could cancel everything by 2...

That source is actually correct. NAD⁺ is reduced to NADH + H⁺. That equation doesn't give the full picture:
NAD⁺+ 2H⁺2e^- --> NADH + H⁺

Two electrons are required to reduce NAD⁺, one for NAD⁺and one for H⁺. However, you only need one H⁺, the other H⁺ acts as an electron carrier which is why its not needed and returns back into the matrix to reduce more NAD⁺. Thus it acts as a catalyst.

I don't know OCR requirements. For AQA, saying reduced NAD or NADH are both fine. I wouldn't think different for OCR.

hmm i'm not sure i understand

NAD+ is charged. Each H atom has 1 electron. Therefore 2 H atoms required to reduce NAD+ to NADH, one to cancel the charge and one to actually reduce it.

is that what you're saying?

but where does the H+ come from?

Reply 8

+

Original post by z33

hmm i'm not sure i understand

NAD+ is charged. Each H atom has 1 electron. Therefore 2 H atoms required to reduce NAD+ to NADH, one to cancel the charge and one to actually reduce it.

is that what you're saying?

but where does the H+ come from?

The H atom does not cancel the charge. It's the electron that cancels the charge. The H⁺ ion is only used to carry the electron, neutralise the NAD⁺ and go back.
You're right that the other H atom does reduce the now uncharged NAD.

The H⁺ comes from two sources: the active site of a dehydrogenase and the Pi group of G3P. If you really really want to know, I'll tell you, but I don't want it to get any confusing for now.

Reply 9

OP

Original post by RMNDK

+

The H atom does not cancel the charge. It's the electron that cancels the charge. The H⁺ ion is only used to carry the electron, neutralise the NAD⁺ and go back.
You're right that the other H atom does reduce the now uncharged NAD.

The H⁺ comes from two sources: the active site of a dehydrogenase and the Pi group of G3P. If you really really want to know, I'll tell you, but I don't want it to get any confusing for now.

haha no i'm alright - I'd like to keep my sanity thank you

but thanks yeah so

2H released

one H splits into an electron and proton, proton is the "+ H+" in the equation that goes off and brings more electrons for canceling more NAD+ etc. electron cancels charge on NAD

the other H out of the 2H that are released reduces the uncharged NAD forming the "NADH" part

if this is incorrect - it's as right as i'll ever be :P

thanks and i'm sorry to bother you so much i'm just too stupid :giggle:

(edited 8 years ago)

Reply 10

Original post by z33

haha no i'm alright - I'd like to keep my sanity thank you

but thanks yeah so

2H released

one H splits into an electron and proton, proton is the "+ H+" in the equation that goes off and brings more electrons for canceling more NAD+ etc. electron cancels charge on NAD

the other H out of the 2H that are released reduces the uncharged NAD forming the "NADH" part

if this is incorrect - it's as right as i'll ever be :P

thanks and i'm sorry to bother you so much i'm just too stupid :giggle:

You're correct wahey. You are not stupid at all. Biochemistry is real complex but it's also fun! Unless you hate it.

Reply 11

OP

Original post by RMNDK

You're correct wahey. You are not stupid at all. Biochemistry is real complex but it's also fun! Unless you hate it.

yay

thank you so much! yeah haha i'm glad i don't hate it so :h:

Reply 12

Thephysicist123

Original post by z33

BAsically y'all

why is NAD not charged in glycolysis but charged in the link reaction?

in glycolysis : NAD + 2H -> NADH + H+

in link reaction: NAD+ + 2H -> NADH

my brain is going to explode i can't find answers :argh:

I have the answer! Basically your subject that you have chosen to do is boring, dull and awful, and involves you studying plants which basically sums up the whole excuse of a science. Next time, choose a proper science such as physics for example. Glad i could help :smile:

Reply 13

OP