Enzymes Flashcards
(24 cards)
What is an enzyme?
A substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction.
Give an example of an enzyme.
Analyse: present in saliva and contributes to the breaking down of carbohydrates (starch).
What are some factors that can affect enzymes?
Enzymes are effected by temperature and PH, and sometimes concentration.
What are some of the theories on how enzymes work?
A lock and key model and the induced fit.
Explain how an enzyme fits into the lock and key theory?
In the same way that a lock fits into a key, so does a substrate and an active site. The substrate and active site have a certain shape that only allows them to fit together. So just like a lock will only accept one key, an active site will only accept one enzyme.
How is an enzyme affected by temperature.
When an enzyme is heated beyond its optimum , its active site changes. Because of this the substrate can no longer fit into it. The enzyme will no longer function in this new shape and is therefore denatured. (irreversibly changed).
What are enzymes made up of?
Proteins: amino acids.
Will an enzyme work on any substance?
No. Enzymes are very specific. They have a certain structure that only allows for a specific substate to fit into.
Are enzymes reusable?
Yes. Enzymes are not changed during the reaction so their energy is conserved. Enzymes will continue to bind to substrates till their are none left.
What is meant by the term substrate?
The substrate is a substance on which an enzyme reacts upon, also known as the reactant of the reaction.
What is meant by the term active site?
The active site is where the reaction occurs/ takes place. The region where an enzyme binds to a substrate.
At what temp. do most intercellular enzymes work best at?
The normal human body temp: 36.5 c.
What PH do most human intercellular enzymes work best at?
Because the human PH is usually neutral, an enzyme in the body works best at around 7.
Explain how competitive inhibitors work.
Competitive inhibitors are molecules that bind to an enzyme preventing it from catalysing its reaction. They are similar to the substrate and compete with it for the active site.
Enzyme can be slowed or halted using inhibitors. True or false.
True.
Will raising the temp. slightly increase r decrease the rate if the reaction?
Increase.
Blowing temperature will increase, decrease or not change the rate of the reaction?
Decrease because it will denature the enzyme.
What will changing the PH to the enzymes optimal level do?
It will Increase the rate of the reaction.
What things can increase the rate of an enzymatic reaction?
- Add more substrate
- Add more enzyme
- Adjust PH to optimal level
How does the level of PH effect the rate of an enzyme reaction?
Different enzymes work best at different pH values, their optimum pH. Many enzymes work fastest in neutral conditions. At extremes of pH the reaction will stop altogether.
What is the induced fit theory of an enzyme?
States that the binding of a substrate to an enzyme causes a change in the shape of the enzyme so as to enhance or inhibit its activity.
At about 0 degrees celsius what are enzymes like?
Enzymes are inactive, they are neither active more denatured. They stop working when the temp gets too cold.
Why is it important for cells that enzymes are not used up in the reaction?
It is important for enzymes to not be used up because then the cell would have to use more energy to make the enzymes. Because enzymes are not used up the cell can conserve its energy and it more efficient for the cell.
Explain the steps of an enzyme reaction.
- The substrate come into to contact with the active site and fit perfectly together, they bind to each other.
- The enzyme and the substrate then react together and produce the product. the substrate is used up but the active site remains unchanged.
