To understand the basic energy rules, view the slideshow
Here is a video on thermodynamics and perpetual motion machines
Perpetual Motion machines and Thermodynamics
Enzymes: First watch this video
Know what substrates are and how they relate to enzyme catalyzed reactions.
Example what is the substrate in this enzyme catalyzed reaction
Lactose→Glucose + Galactose?
The enzyme in this reaction is lactase
Know how enzymes catalyze biological reactions, specifically their effects on activation energy.
Another concept in how enzymes speed up reactions is activation energy. Imagine you have a homework assignment due next week. You could do it now, or you could put it off until right before it is due. The activation energy is the energy needed to get the process started. Note that the homework might take you an hour whether you do it now or later. The activation energy is just what it takes to get started. Enzymes decrease activation energy as shown in the diagram in the link
Note that that the ΔG (The overall energy) does not change whether or not the enzyme is present. Enzymes also have no effect on the equilibrium of a reaction; adding an enzyme does not shift the reaction to the left or right. It does change how quickly the reaction reaches equilibrium.
Understand how compounds that bind to the active site or allosteric site can alter enzyme function
Many drugs can inhibit enzyme function by binding to the active site. Here is an example
The key point here is that the inhibitor binds very strongly to the active site preventing the substrate from binding. Because both the inhibitor and substrate bind to the same site, the binding is said to be competitive. If the concentration of substrate increases, the inhibitor is less effective.
We have already mentioned active sites, they bind to the substrate(s) of a reaction. Some enzymes also have allosteric sites. These do not bind to substrates but they bind to compounds that can turn on (activators) or turn off (inhibitors) an enzyme as shown in this video
Allosteric regulation of enzymes
Non-competitive inhibitors bind to the allosteric site. Adding more substrate has no effect on allosteric inhibitors since the inhibitor changes the active site to be “closed”.
Know what feedback inhibition is and how it can be used to control amino acid synthesis.
Here is an example of how this works to control amino acid levels
Feedback inhibition o f amino acid synthesis
