enzymes.pngare proteins that regulate and facilitate chemical reactions at an energy level compatible with life (imagine starting a fire in your muscles to burn sugar...).

Enzymes are also emphasized on the AP because of their role in EVERY life process.


Task One:
Watch the video posted below.
Make notes on the important points of enzymes

Visit this website and roll through each flash animation on enzymes. Watch and understand the important points of enzymes.
Task Two: Complete guided reading notes on ch 8.
Remember to watch the power point first and then read the chapter


Task Three:
Student Research Presentations posted to the wiki (Below). Research topics include:
  • Cofactors
  • Competitive Inhibitiors
  • Noncompetitive Inhibitors
  • Allosteric Activators
  • Allosteric Inhibitors
  • Feedback Inhibition

What is expected of each presentation:
  • a clear definition (non textbook) of each topic
  • a clear example of each topic
  • the importance of the topic relative to its function in a reaction or the human body (clinical cases or applications work well - for example disulfiram is used to treat alcoholics because it blocks the enzyme that breaks down alcohol, causing severe illness 5 minutes after having a drink).
  • a graphic or video clearly showing what you are explaining


Cofactors- non-protein molecules that react with an enzyme and either affect its function or are acted upon by said enzyme. Their effects may be permanent or transitory. Inorganic cofactors such as iron, copper, and zinc assist the enzymes. Organic cofactors, often referred to as coenzymes, are often made of vitamins and raw materials. They act out fuctions in catalysis.




Competitive Inhibitors - Competitive Inhibitors are inhibitors that are in the same shape as substrates that bind to the enzyme. Instead of the substrate binding to the active site in the enzyme, the competitive inhibitor binds to the active site. In doing this, the active site is blocked and the actual substrate cannot bind to the enzyme in order to be broken down. Very boring but simple video to understand:
- Chris A.



Noncompetitive Inhibitors
Noncompetitive Inhibitors are inhibitors that reduce the activity of an enzyme by binding to a location remote from the active site, this causes a change in its conformation so that it no longer binds to the substrate. In simpler terms, if an inhibitor can bind to an enzyme at a site that is different from the actual active site it is noncompetitive meaning it doesn't compete for the same location. This process will decrease the overall rate of reaction.
-Dahlia M.enzymes_noncompetitive-inhibitor_400.jpg
-Mike G


Allosteric Activators

An allosteric activator is a molecule that binds to a regulatory site on an enzyme and stimulates the enzyme to complete its function. It basically means that in order for the enzyme to complete its function it needs to wait for both of 2 different molecules to complete its process.






Allosteric Inhibitors
The binding of an inhibitor stabilizes the inactive form of the enzyme. Subunits fit together, so that conformational change is transmitted to all units of a cell. A single inhibitor molecule that binds to one regulatory site will affect the active sites of all subunits. The allosteric site is not the main site of an enzyme. It is simply a side unit, and no substrates will ever attach to the allosteric site. The allosteric site cannot perform any tasks without "permission" of the main active site.


allosteric_kjsbkgb.jpg




Feedback Inhibition:

Feedback inhibition is that after a product is no longer needed, the substrate will connect to the alloerstric site and stop production of that product.
An example of feedback inhibition is a thermostat connected to a heater. A sensor detects the temperature in the room, and when the temperature reaches a specific point, the thermostat signals the furnace to shut off. When the temperature drops below the set point, the inhibition is released, and the furnace is turned back on.
Last 30 seconds really important!