Question

Can someone please explain to me Glycolysis?

Answer 1

What do you want to know about the glycolysis?

Answer 2

Just want to know the main focus so I can make the best answer that suit you.

Answer 3

I can't actually understand it, I know the overview of it but I don't understand it in depth and since Im at the citric acid cycle I need to go back cause im lost

Answer 4

Well.. the glycolysis is in theory just all about making all sugars into pyruvate which can then enter citric acid cycle.

Answer 5

I know that . . . haha I just see here is what I know. I know that glycolysis the splitting of glucose. but I don't understand the process of it.

Answer 6

Alright. So what you basically want is the mechanism? We can also take about that how is your organic chemistry?

Answer 7

And obviously we talk about why each individual step is important. Empthesis on the phosphorylated intermediates

Answer 8

Yes that's what I want. And to be honest, I didn't take chemistry or regular bio I just jumped in so that's why im confused...

Answer 9

Alrightie. I try make some good notes you can use then. :)

Answer 10

Thank you so much!

Answer 11

The glycolysis is a very logic reaction from the view of a organic chemist. and the following is an attempt to recap it:


First what we do is to do a phosphorylation of glucose that ensure that the pathway intermediates does not leave the pathway, the idea behind is is that the plasma membrane in general lacks transporters for phosphorylated sugars, that way ensure that the phosphorylated intermediates does not leave the cell and no further energy has to be used to keep the sugars inside, even when considering the high large difference in concentration intracellular and extracellular.

Phosphorylation occures on C-6 as C-1 is a carbonyl group and can therefor not be phosphorylated.

Using a isomerization you can move the carbonyl to C-2 which enable you to do a phosphorylation on C-1 which is now a hydroxyl group.

The reason you want them both phosphorylated is the same argument as before, if both C-1 and C-6 was not phosphorylated before cleavage then you lose 50% of your sugar due to the large concentration difference.

The cleavage is equal to the reverse of an adol condensation, and yields 2x 3-carbon products.

PART 1

Answer 12

Thank you I understand this part now a bit better, things like this aren't explained in my book

Answer 13

Want me fast to write for the rest of the reaction? Or was it mostly the wondering why phosphorylation was important? :)

Answer 14

Yes please write the rest it would help me a ton!

Answer 15

From the 2x 3-carbon products one of them needs to be changed (dihydroxyacetone phosphate) into glyceraldehyde 3-phosphate such that only a single pathway can be used.

From glyceraldehyde 3-phosphate you can do a oxydative phosphorylation which produce 1 NADH (and as you know is the prerequisite for ATP production).

a ATP production happens using what is called a substrate-level phosphorylation. This happens when 1,3-bisphosphorglycerate is made into 3-phosphoglycerate.

The remaining phosphoryl group moves from C-2 to C-3 and then from here it is just all about making 2-phosphoglycerate. We do this by doing a dehydration which activate the phosphoryl transfer to ADP (phosphorenolpyruvate) and finally we remove the phosphoryl group making ATP and pyruvate which is ready to leave into the mitochondria to produce Acetyl-CoA (which I guess is aprox where you are now) :)

Answer 16

Yes thank you I understand it a bit better now :) is really helpful. Thanks.

Answer 17

No problem at all. If there are anything else you wonder about specifically regarding the glycolysis, feel free to ask.

Answer 18

Oh yes better write fast why doing a oxidative phosphorylation is more important than a substrate-level phosphorylation

Answer 19

I was gonna ask about that.

Answer 20

If you follow one glucose molecule you get 2 ATP from the glycolysis. This is because we do a 2x physphorylations and 2*2x substrate-level phosphorylation. leaving only -2+4=2 ATP produced.
At the same time you produce 2x NADH which is equal to 3 or 5 ATP (depending on the mechanism used) (which you will learn later in the critic acid cycle)

Answer 21

In basic: NADH is more rich on ATP in the end for energy production than ATP created during the pathways.

Answer 22

Ohh okay and this is why oxidative phosphorylation is more important than the other? And this is the last step in cellular respiration right?

Answer 23

You can say so yes.
Basically you can devide all metabolism into a general model like this:

Food (containing sugar, fats and proteins) is going into their pathways to be broken down to produce acetyl-CoA. Sugar uses the glycolysis, fats use beta-oxidation and amino acids their respective pathways. All the acetyl-CoA is then being oxidized in the citric acid cycle to yield electrons in the form of reduced eletron carriers (NADH and FADH2) which can then enter the electron transfer and oxidative phosphorylation yes.
Each pathway depend on each other to fuel each other :)

Answer 24

Well now this makes complete sense ! thanks!

Answer 25

Glad to hear that! :) We can finish with a fast little fact that kinda support your statement "the oxidative phosphorylation is most important"....
You know the chemical cyanide?

Answer 26

Yes I do :)

Answer 27

Well you know cynaide kills :)
And I can tell you it functions by stopping the electron transfer and thereby the oxidative phosphorylation.

Answer 28

the oxidative phosphorylation stops*

Answer 29

And as I've said many times now, if anything else you wonder about, please feel free writing to me. :)