May someone explain the process of glycolysis?Don't need to elaborate on the ten steps. I don't get how the 2 NADH are produced in the process and the fact it needs two atp molecule as an...

May someone explain the process of glycolysis?

Don't need to elaborate on the ten steps. I don't get how the 2 NADH are produced in the process and the fact it needs two atp molecule as an investment but end up making 2 atp molecules per glucose. All I know that the glucose is broken into 2 three carbon molecule called pyrurate.

Expert Answers
nofret eNotes educator| Certified Educator

Wow! I love how specific your question is!  You explained exactly which part about it you don't understand.  That helps me a lot.  At first, to break the bonds in the glucose molecule, the glucose uses ATP to phosphorylate it.  (Just adds a phosphate molecule)  This molecule is now called "glucose-6-phosphate" because the phosphate from the ATP is added onto the glucose molecule at carbon #6.

Then, an enzyme changes the molecule from glucose-6-phosphate to fructose-6-phosphate.  Then our 2nd ATP is used  to add a second phosphate group on to our molecule making it fructose-1,6-biphosphate.  ( There are 2 phospates on the molecule now. That's where the "bi" comes from and they are on carbon #s 1 and 5).  This is the initial investment of ATP.

Now for the NADH.  Remember this: NAD+ is a bus.  H ions ride on the bus.  So NAD+ is the empty "bus" and NADH is the full "bus".  In step 6, the molecules each lose a H ion. the NAD+ "bus" comes and picks them up and takes them to the electron transport chain.  That's how your 2 NADH molecules are produced.

Now to get back your initial ATP investment.  To make ATP from ADP, you just have to add a phosphate.  In step 7, the 2 molecules each lose a phosphate and those phosphates are attached to  2 ADP to make  2 ATP.  Now you have your initial investment of 2 ATP back and the "debt" has been paid.

Hope this helps!