ATP: The Molecule of Energy

What are Enzymes Made Of?

Enzymes are made of a priten part called an APOENZYME that gives the enzyme its specific function and determines which reaction it will catalyze and where.
Also, an enzyme is made up of a non-protein part called a COENZYME which helps the reaction the enzyme initiates by accepting and donating hydrogen ions.
- Coenzymes function to give hydrogen ions to the reaction occuring within the enzyme.
  - Coenzymes can be vitamins!

Oxidation reactions function to remove hydrogen ions and electrons
They are also accompanied by a release of energy that they generate and thus are EXOTHERMIC REACTIONS.

Cells use ATP when they need energy
ATP us the energy currency in biological system as it is used in all cellular reaction, like synthesis, muscle contractions, active transport, etc, that require energy in order to proceed.
An ATP molecule has two high-energy phosphate bonds that when broken release LOTS OF ENERGY
When these phosphate bonds are broken ATP changes to a molecule called ADP which has one less phosphate group.
However, if energy is added to the system then ADP can bind to the phosphate group that was broken off and remake an ATP molecule. This process is constantly occurring in the mitochondria.
During energy transfers neither ATP, ADP or the phosphate group that breaks off are lost rather these molecules can be reused and remade after breaking apart.

All organisms carry out cellular respiration to produce energy (ATP0 from food items. However, oxidization & reduction reactions allow this to occur in the presence of oxygen and cause ATP to be produced from the food we eat.
This is important since this reaction is a metabolic pathway that produces the most amount of ATP from many small intermediate reactions.
- Eg. 38 ADP + 38 Pi (phosphate groups) --->38 ATP

In animal and plant cells oxidation cellular respiration occurs.

C6H12O6 (glucose from a food item) + O2 ---> 2H2O + ATP (energy)
- From the glucose molecule hydrogen atoms are released and therefore, form water and carbon dioxide. As a result, this reaction is exothermic and energy is released.

Reduction cellular respiration occurs in ONLY PLANT CELLS.

6Co2 + 6H20 + light energy (ATP) ---> 6O2 + C6H12O6 (glucose)
- In this reaction hydrogen atoms from water are added to the carbon dioxide molecule and oxygen molecules are released in order to create glucose. Therefore, since this reaction is a reduction reaction, energy or ATP is a reactant (endothermic) that must be used up in the reaction in order to allow it to proceed.