7.2 Study Guide Flashcards
What is an enzyme?
Enzymes are proteins that are catalysts for chemical reactions. The enzymes bind to substrates at the active site in order to put molecules together or break them apart. Enzymes limit the amount of activation energy needed for the reaction to occur.
What is a substrate?
A substrate is a reactant in a chemical reaction. Substrates bind to enzymes to perform chemical reactions. Substrates can be joined together or broken apart.
What is an active site?
The active site is the point where the substrates bind to the enzyme.
What is activation energy?
Activation energy is the minimum amount of energy needed to activate the enzymes and substrates in order for the chemical reaction to occur.
What are the properties of enzymes?
- Reaction specific: Enzymes only bind with particular substrates. Each enzyme=specific substrate
- Not consumed in the reaction. single enzyme=lots of the same reactions
- Made of protein (sometimes RNA)
- Affected by cellular conditions: Denatured by certain temperatures or concentrations of ions (pH and salinity)
What is the relationship between reaction rate and substrate concentration?
A greater substrate concentration allows for more collisions to occur, which increases the chances of having more successful collisions with enzymes. This will increase the reaction rate. Eventually, the substrate concentration will get too high and the substrates will collide with each other and the enzymes will be maxed out. This will level out the reaction rate.
What is the relationship between reaction rate and enzyme concentration?
A greater enzyme concentration allows for more collisions with substrates, which can lead to more successful reactions. This will increase the reaction rate. Eventually, the enzyme concentration will be too high and the enzymes will collide with each other. This will level out the reaction rate.
What is the relationship between reaction rate and temperature?
As the temperature increases, the molecules move faster. This results in more successful collisions, which increases the reaction rate rapidly. However, once the temperature gets too hot, the enzymes start to denature. This makes the reactions less likely or impossible to occur because the substrates will not fit into the enzymes. This decreases the reaction rate rapidly.
What is the relationship between reaction rate and pH?
If the proteins are too acidic or basic, the enzymes can denature. The pH has to be just right for the substrates and enzymes to have a successful collision. If the pH is too basic or acidic, the enzymes will not be able to bond with the substrates. Thus, the reaction rate can increase and decrease rapidly depending on the pH level.
How would you maximize enzyme activity considering all of the factors discussed in class? Minimize?
To maximize the enzyme activity, you would have to keep the concentration of enzymes and substrates at a medium level so there is a greater chance of successful collisions and reactions, but not too high to the point where the enzymes become maxed out or run into each other. The temperature would have to be kept at the optimal level for each enzyme, which is 37 degrees Celsius for many enzymes. This would allow the enzymes and substrates to move rapidly without the enzyme starting to denature. The pH would also have to be kept at the enzymes optimal pH level so that it does not denature.
To minimize enzyme activity, you would have to make the concentration of enzymes and substrates very high, make the temperature very hot, and make the pH very acidic or very basic. The pH would have to be as far away from the optimal pH as possible.
Compare and contrast inhibition and activation of enzymes
Activators activate enzymes and inhibitors inhibit enzymes. Activators and inhibitors both change the shape of enzymes. However, activators change the shape of the active site so substrates can bind with the enzymes. Oppositely, inhibitors change the shape of the active site so the substrate cannot bind with the enzymes. Noncompetitive inhibitors affect enzymes by changing the shape of the enzyme, but at a place other than the active site. Competitive inhibitors interferes with the active site so the enzyme cannot bind with substrates.
