Diy Glycolysis Home Page

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Design it Yourself Glycolysis is an educational aid which I hope will give you some insight into the function of this metabolic pathway. Step by step you will 'design' glycolysis from scratch and by doing so you can compare your selections with the real pathway which evolved billions of years ago. Please note that this resource is NOT a quiz. To get the most out of the exercise it's important that you deliberately select wrong answers to the questions that are presented to you.

Introduction

The aim of this exercise is to help you understand the processes which occur in (anaerobic) glycolysis. Starting with glucose you will choose the reaction types in sequence which will achieve the desired end point. I.e.:

1. Glucose converted to lactate.

2. ATP generated.

3. Oxidation balanced with reduction.

It is assumed that you have been introduced to glycolysis already - this application is intended to help you consolidate your understanding. You can still work through the exercise even if you are new to glycolysis by using a lot of trial and error.

The Task Ahead

In the transformation of glucose to lactate the hexose is split into two halves and the atoms are rearranged. The empirical formulae of glucose and lactic acid are;

So it's possible to make two moles of lactic acid from one mole of glucose with no net addition or removal of atoms.

Although lactic acid has the right empirical formula for a monosacharide carbon 1 is more oxidised and carbon 3 is less oxidised than the closest monosacharide - glyceraldehyde. So you need to split glucose into two three carbon monosacharides and then rearrange.

Glyceraldehyde Lactate

Keeping Track

You need to keep track of the amount of ATP you have made and the level of oxidation/reduction. A status line at the bottom of the page will do this for you. You will 'spend' ATP if you use it to phosphorylate and 'earn' ATP if you dephosporylate the substrate by transfering the phosphate group to ADP. Redox is reckoned as the number of electrons removed from glucose.

When you split glucose in two you will have two moles of substrate per mole of glucose so each step will count twice.

Summary of Reaction Types

Here is a list of the reaction types available to you.

• Aldol Cleavage

• Aldose-Ketose Isomerisation

• Ketose-Aldose Isomerisation

• Dehydration

• Phosphorylation

• Phosphoryl Shift

• Dephosphorylation

• Coupled Oxidation & Phosphorylation

• Oxidation

• Reduction

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Aldol Cleavage

An aldol is an aldehyde or ketone which has a hydroxyl group attached. In the diagram the black atoms are necessary for this reaction. The R groups may be hydrogen or extended carbon skeleton. Monosaccharides are aldols and can be subjected to this reaction. You should note that in the process one hydrogen atom is moved and a new aldehyde group is formed. When a monosaccharide is cleaved in this way the two products are both monosaccharides. The product with the blue R group must be an aldose. The other product, if a triose or larger will be a ketose. The Delta-G for the reaction will be near zero but there is a significant activation energy at physiological conditions which means the reaction requires an enzyme catalyst.

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