Glycolysis

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DEMO

Investment Phase

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ATP Molecules

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Three-Carbon Sugars

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PGAL

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Pyruvate

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Four ATP Molecules

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NADH

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Glycolysis

Glycolysis is the metabolism of sugar in the body. The word is of Greek origin, and comes from the words glykys, meaning sweet, and Iyein, meaning to loosen. Glycolysis is one of the many processes involved in the formation of Adenosine Triphosphate, more commonly known as ATP. ATP is an energy storage chemical that the body uses to store and release energy. The goal of glycolysis is to turn the glucose into pyruvate. There are nine steps to glycolysis, all of which involve specific enzymes and structures.

  1. Hexokinase

In order to change glucose to something the body can use, the glucose must first be broken down. To start this, the outside ring of the glucose is phosphorylated. This means that a phosphate group is added to a molecule that has been derived from the ATP. At this stage of glycolysis, one molecule of ATP has been used. The enzyme kinase is used to complete this change. Once this step has been completed, the resulting molecule is glucose-6-phosphate.

  1. Phosphoglucose Isomerase

During this phase, the glucose-6-phosphate is changed to a fructose-6-phosphate. This is accomplished through an isomerase reaction. The enzyme phosphoglucose isomerase is the enzyme used. The carbon oxygen bonds are reformed, and the six ring molecule becomes a five ring molecule. As the six ring molecule opens up and then closes, the extra carbon is left on the outside of the ring.

  1. Phosphofructokinase

After the first two steps have finished, the molecule that is now the fructose-6-phosphate is ready to be converted to a fructose-1,6-biphosphate. Another ATP molecule is used during this step. This phosphate group is added to the fructose-6-phosphate, and the molecule becomes phosphofructokinase. In order to prevent negative charges from affecting anything, a magnesium atom is used.                    

  1. Aldolase & Triphosphate Isomerase

This step requires the help of the enzyme Adolase. Adolase is able to cut the fructose-1,6-biphosphate and turn it into 2 molecules. Both new molecules created by this split have 3 carbons. They are called glyceraldehyde-3-phosphate and dihydroxyacetone phosphate. Dihydroxyacetone phosphate cannot be used in this form. Another enzyme, triphosphate isomerase is used to turn it into the glyceraldehyde-3-phosphate.

  1. Glyceraldehyde-3-phosphate Dehydrogenase & NAD

Two different enzymes, glyceraldehyde-3-phosphate dehydrogenase and nicotinamide adenine dinucleotide(NAD), will be used during this step.                                                            

The reaction involves the use of a free phosphate group that will phosphorylate the glyceraldehyde-3-phosphate molecules. That will cause the glyceraldehyde-3-phosphate dehydrogenase molecule to release a 1,3 bisphoglycerate, NADH, and a hydrogen atom.

  1. Phosphoglycerate Kinase

Phosphoglycerate kinase changes 1,3 bisphoglycerate to 3 bisphoglycerate. During this step, a phosphate group is lost. This phosphate is used with a molecule of adenosine diphosphate. The resulting product is a molecule of adenosine triphosphate.

During the previous steps, two molecules of adenosine triphosphate were used. Because we had created two molecules of 1,3 bisphoglycerate, we now have two molecules of adenosine triphosphate. The net amounts of these molecules used during the process is now zero. Because the molecules need to be protected from any negative charges, a magnesium atom is used.

7. Phosphoglycerate Mutase

Phosphoglycerate mutase is used to reposition a phosphate group on the 3 phosphoglycerate molecule, which turns it into a 2 phosphoglycerate molecule. A phosphate group is added to a different position on the molecule. That allows the molecule to release a phosphate on a different part of the molecule and to create the 2 phosphoglycerate molecule.

  1. Enolase

The enzyme enolase is used as a catalyst in this step. Enolase removes a water group from the 2 phosphoglycerate molecule. The dehydrated molecule then goes through several chemical reactions until phosphoenolpyruvate is formed.

  1. Pyruvate Kinase

The last enzyme needed for this process is pyruvate kinase. Two more molecules of adenosine triphosphate are formed when a phosphate group is added to the phosphoenolpyruvate. This generates two molecules of adenosine triphosphate ,as there are two molecules of phosphoenolpyruvate.

Wrapping Up

Now that all of the steps are completed, a little math is all that is left to wrap up this reaction. There were two molecules of ATP used in the first steps of the process. During latter steps, two molecules were created to offset the ones that were used. In the last steps, an additional two molecules were created, leaving the body with two molecules of ATP.

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