Glycolysis (glyceraldehyde 3-phosphate to pyruvate)

OP

I've just seen something and it looks as though the extra phosphate group comes from the NAD when it is reduced, could someone please explain how this happens? :smile:

cheers

Reply 2

Original post by tdx

In glycolysis when glyceraldehyde 3-phosphate is turned into pyruvate, how does two ADP molecules get phosphorylated to two ATP molecules when there is only one phosphate group on the glyceraldehyde 3-phosphate? where does this extra phosphate group come from? thanks for any help :smile:

I'm studying AQA A-level Biology by the way :smile:

Original post by tdx

I've just seen something and it looks as though the extra phosphate group comes from the NAD when it is reduced, could someone please explain how this happens? :smile:

cheers

The extra phosphate group comes from Phosphoric acid - H₃PO₄.

Glycolysis diagram in spoiler:

Spoiler

If you want a larger image, go here.

Reply 3

Bromine

EDIT: Nvm, above makes me realise I clearly need to revise more :tongue:

(edited 12 years ago)

Reply 4

I thought it was each one produces one ATP: 2 pyruvate molecules are produced for each glucose molecule. I do OCR though, so you may learn it a bit different

Reply 5

OP

Original post by thegodofgod

The extra phosphate group comes from Phosphoric acid - H₃PO₄.

Glycolysis diagram in spoiler:

Spoiler

If you want a larger image, go here.

ahh, thanks :smile:

so that's where the H+ ion also comes from then? just a quick question where does the Phosphoric acid come from? or is it just in the cell's cytosol already?

cheers :')

(edited 12 years ago)

Reply 6

OP

Original post by Bromine

EDIT: Nvm, above makes me realise I clearly need to revise more :tongue:

aha, what did you put then? :')

Reply 7

Original post by tdx

ahh, thanks :smile:

so that's where the H+ ion also comes from then? just a quick question where does the Phosphoric acid come from? or is it just in the cell's cytosol already?

cheers :')

Just in the cell's cytosol - probably formed during the break down of phosphate-containing molecules, such as phospholipids.

Reply 8

OP

Original post by Obfuscator

I thought it was each one produces one ATP: 2 pyruvate molecules are produced for each glucose molecule. I do OCR though, so you may learn it a bit different

Glycolysis in short:

Glucose --> Phosphorylated glucose (2ATP --> 2ADP) --> 2 x glyceraldehyde 3 phosphate --> 2 x Pyruvate (4ADP --> 4ATP and 2NAD --> 2NADH + 2H+)

(edited 12 years ago)

Reply 9

OP

Original post by thegodofgod

Just in the cell's cytosol - probably formed during the break down of phosphate-containing molecules, such as phospholipids.

ok, thanks :smile:

so it is where the H+ comes from aswell then?

Reply 10

Original post by tdx

ok, thanks :smile:

so it is where the H+ comes from aswell then?

Which H⁺?

The ones when NAD⁺ is reduced to NADH + H⁺?

Those hydrogens come from the molecule that is being oxidised by NAD⁺.

Reply 11

I'mBadAtMaths

14

Original post by tdx

In glycolysis when glyceraldehyde 3-phosphate is turned into pyruvate, how does two ADP molecules get phosphorylated to two ATP molecules when there is only one phosphate group on the glyceraldehyde 3-phosphate? where does this extra phosphate group come from? thanks for any help :smile:

I'm studying AQA A-level Biology by the way :smile:

The two ATP molecules in the 'energy generation phase' are formed by substrate level phosphorylation, which is when a phosphate containing molecule which releases more energy on hydrolysis than ATP is used to phosphorylate ADP; these high energy molecules are 1-3 bisphosphoglycerate and phosphoenol pyruvate, which form 3- phosphoglycerate and pyruvate respectively after donating a phosphate group to ATP.

Remember 2 molecules of glyceraldehyde-3 phosphate form from glucose, so there are actually 4 molecules of ATP formed in the energy generation phase.

Reply 12

Original post by tdx

Glycolysis in short:

Glucose --> Phosphorylated glucose (2ATP --> 2ADP)--> 2 x glyceraldehyde 3 phosphate --> 2 x Pyruvate (4ADP --> 4ATP and 2NAD --> 2NADH + 2H+)

In OCR we learn it as:

Gucose --> Glucose 1-phosphate --> Fructose 6-phosphate --> Fructose 1,6-phosphate --> 2x Triose Phosphate --> 2x Intermediate Compound (Presumably glyceraldehyde, we don't need to know it) [2x Reduced NAD & 2x ATP from ADP] --> 2x Pyruvate (2x ATP)

Slightly different, but the premiss is the same.

Reply 13

Original post by Obfuscator

In OCR we learn it as:

Gucose --> Glucose 1-phosphate --> Fructose 6-phosphate --> Fructose 1,6-phosphate --> 2x Triose Phosphate --> 2x Intermediate Compound (Presumably glyceraldehyde, we don't need to know it) [2x Reduced NAD & 2x ATP from ADP] --> 2x Pyruvate (2x ATP)

Slightly different, but the premiss is the same.

You guys go into more detail for glycolysis - AQA are sissies when it comes to biochemistry :frown:

Reply 14

I'mBadAtMaths

14

Original post by thegodofgod

Just in the cell's cytosol - probably formed during the break down of phosphate-containing molecules, such as phospholipids.

No, the phosphate that is used to make ATP from ADP comes from intermediates of glycolysis (obviously in A level you don't learn all of the details, but ADP is definitely not phosphorylated using phosphates from phospholipids!)

Reply 15

Original post by thegodofgod

You guys go into more detail for glycolysis - AQA are sissies when it comes to biochemistry :frown:

Hahaha I swear OCR is the hardest one. I tried some questions from AQA, they were soo easy. No offence :biggrin:

Reply 16

Original post by I'mBadAtMaths

No, the phosphate that is used to make ATP from ADP comes from intermediates of glycolysis (obviously in A level you don't learn all of the details, but ADP is definitely not phosphorylated using phosphates from phospholipids!)

No - I'm saying that phosphoric acid is used to phosphorylate 1 x Fructose-1,6-bisphosphate (2 phosphate groups) --> 2 x 1,3-bisphosphoglycerate (4 phosphate groups).

Reply 17

Original post by Obfuscator

Hahaha I swear OCR is the hardest one. I tried some questions from AQA, they were soo easy. No offence :biggrin:

Yeah - stupid AQA (at least for biology) are all about the How Science Works rather than proper Science!

And what's worse, is that the questions are so badly phrased, and EVEN worse, their mark schemes are atrocious! :rant:

Reply 18

Original post by thegodofgod

Yeah - stupid AQA (at least for biology) are all about the How Science Works rather than proper Science!

And what's worse, is that the questions are so badly phrased, and EVEN worse, their mark schemes are atrocious! :rant:

OCR's bad for phrasing and mark schemes too. It drives me absolutely INSANE when I loose marks but still have essentially the right answer, just didn't use the exact word they wanted to see.

Reply 19

OP