Energy: The ability to do work, which can be thought of as the ability to cause some kind of change
Types of Energy:
- Kinetic energy: Energy of motion
- Potential energy: Energy due to position or structure
- Chemical energy: The potential energy of chemical bonds
Energy Conversions: Energy can be converted from one form to another. For instance, energy stored in bonds of the small molecule ATP (potential energy) can power the contraction of muscle cells to move a limb (kinetic energy)
ATP: ATP stands for adenosine triphosphate
ATP is composed of a ribose sugar, an adenine nitrogenous base and three phosphate groups.
ATP is the energy currency of cells. ATP stores potential energy in the chemical bonds between adjacent phosphate groups. Breaking the phosphate bond releases energy which can be used to drive cellular processes.
Catalysts: substances that help a chemical reaction to occur
Enzymes: protein catalysts
Activation energy: The minimum amount of energy needed to activate or energize molecules or atoms so that they can undergo a chemical reaction
How enzymes work? Enzymes lower the activation energies of chemical reactions inside the cell. Enzymes do this by binding to the reactant molecules, and holding them in such a way as to make the chemical bond-breaking and bond-forming processes take place more readily.
Naming Enzymes: Enzymes are named by adding the suffix -ase to the name of the substrate that they modify.
Example: Sucrase catalyzes the hydrolysis (break down) of
sucrose into glucose and fructose
Enzymes and Optimum Environments: The conditions under which a particular enzyme is most active is called the optimum. Enzymes optimums will be particular to the environment in which the cell typically resides. Example: The bacterium Thermus aquaticus lives in hot springs. Its enzymes have an optimum temperature of around 70 oC.
