1. An Enzyme Example – Glycolysis the breakdown of glucose from a 6 to a 3 carbon molecule
Glycolysis is the essential pathway in all living things. It is the collection of chemical reactions that get the energy out of glucose so it can be used to dot he cells business. The energy is stored in the glociuse chemical bonds. In this pathway (aka collection of chemical reactions) enzymes break glucose’s bonds and transfer the chemical energy to ADP (the universal energy currency of the cell) and NAD (another currency in the cell).
We chose this example because it introduces you to glycolysis, a “metabolic pathway” we will be studying in great detail and it showcases some well studied and understood enzymes.

2. Summary Equation 
Glucose (C6H12O6) is broken down into 2 molecules of pyruvate. Pyruvate is the starting point for the second, more complex part of cellular respiration, the Krebs cycle, another pathway we will study in great detail. Several other molecules make their appearance in the glycolysis pathway. There are ADP and ATP and NAD+ and NADH.
ATP (adenosine triphosphate) is the energy currency of the cell. Energy stored in its phosphate bonds are used throughout the cell to drive thousands of different chemical reactions. As glucose is broken down in glycolysis, the energy in some of the glucose chemical bonds is transferred to ATP. In this step, the energy from glucose is used to add a thrid phosphate group to the molecule ADP, adenosine diphosphate. When ADP is converted to ATP, energy is dtored in the bond. When ATP is converted to ADP, energy is transferred to another molecule or used for work in the cell.
NADH (Nicotinamide adenine dinucleotide) acts as an electron shuttle bus in cells. As NAD+ it is available to accept electrons from a molecule upon which it becomes NADH. As NADH it has electrons available to donate to another molecule.
Finally Pi is a symbol for inorganic phsphate that exists in the cell in small amounts.

3. So here is the glycolytic pathway – 10 steps to pyruvate
So here is the glycolytic pathway – 10 steps to pyruvate. Each step is carefully controlled and choreographic by a specific enzyme. The diagram shows where ADP and ATP, NAD+ and NADH and Pi play roles. It also shows how the 6 carbon molecule, glucose, is altered and cut into 2, 3 carbon molecules of pyruvate. Finally one sees which steps generate energy and which steps require energy.

4. Hexokinase
The first step is controlled by the enzyme hexokinase. Hexokinase is a well studied enzyme and as such gives us the opportunity to see the enzyme in action. In the active pocket of the enzyme, glucose loses a hydrogen ion and gains a phosphate group from ATP.

5. Hexokinase Active Site
The first step is controlled by the enzyme hexokinase. Hexokinase is a well studied enzyme and as such gives us the opportunity to see the enzyme in action. In the active pocket of the enzyme, glucose loses a hydrogen ion and gains a phosphate group from ATP.

6. The first step is controlled by the enzyme hexokinase
The first step is controlled by the enzyme hexokinase. Hexokinase is a well studied enzyme and as such gives us the opportunity to see the enzyme in action. In the active pocket of the enzyme, glucose loses a hydrogen ion and gains a phosphate group from ATP.  +

7. Fructose Diphosphate Aldolase

8. Enzymes:
specific to a chemical reaction
large proteins
active binding site
recycle