What are enzymes and what factors are they affected by?

Enzymes are proteins that catalyze nearly all reactions that go on in your body that would otherwise be too slow for survival. The substances or molecules that enzymes catalyze are called substrates, and the site of the enzyme where they bind is called the active site. There are three factors that affect enzyme activity: - Temperature: as temperature increases, substrate and enzyme molecules have more kinnetic energy and they have a higher chance of collision, which increases enzyme activity. However, once the optimum temperature at which the enzymes work is exceeded, the structure of the enzyme and the active site changes and they become denatured (enzyme 'death'), and thus activity falls. - pH: similarly to temperature, enzymes have an optimum pH. At their optimum pH, enzymes work at their fastest rate. If the pH alters, the bonds that hold enzymes together break and they rapidly become denatured. - Substrate concentration: if the substrate concentration is increased, there are more active site - substrate collisions and activity rapidly increases. However, enzymes get occupied quickly (they get saturated) as the activity reaches its peak. After that point, an increase in substrate concentration does not have an effect on enzyme activity.