Enzyme Function & Regulation Flashcards
Metabolism (16 cards)
What are enzymes?
Enzymes are biological catalysts that can speed up chemical reactions by lowering the activation energy.
What do enzymes allow?
Enzymes allow chemical reactions to occur at a fast-enough rate at body temperature for the body to function.
How does pH levels affect enzyme activity?
Enzymes are very sensitive to the pH of the medium in which a reaction is taking place.
Each enzyme has an optimum pH at which it will work most effectively.
How does temperature affect enzyme activity?
Temperature influences enzyme activity. The rate of most chemical reactions increases as temperature increases
At what temperature do enzymes become denatured?
Because enzymes are proteins, beyond about 45–50°C their structure changes; they are denatured.
As the shape of the enzyme is crucial for its functioning, denatured enzymes are inactive.
What is the optimum temperature for enzymes?
The temperature at which an enzyme works best is called the optimum temperature.
For most enzymes in the human body, this is 30°C to 40°C.
What are enzyme inhibitors and how do they affect enzyme activity?
Enzyme inhibitors are substances that slow or even stop the enzyme’s activity. Inhibitors may be used by cells to control reactions so that products are produced in specific amounts.
Provide an example of an enzyme inhibitor
Many drugs are enzyme inhibitors; for example, penicillin inhibits an enzyme in bacteria that is involved in construction of the cell wall
How does enzyme concentration affect enzyme activity?
The higher the concentration of enzyme, the faster the rate of a chemical reaction because there are more enzyme molecules to influence reactants.
How does the body control which reactions occur?
By regulating the type and number of enzymes present, the body can control which reactions occur and the rate at which they proceed
How does substrate concentration affect enzyme activity?
Increasing substrate concentration also increases the rate of the reaction.
This occurs because there will be more substrate molecules encountering the enzyme molecules.
What happens when the substrate is increased beyond a certain concentration?
Increasing the substrate beyond a certain concentration will cease to have an effect because the active sites on all the enzyme molecules will be fully occupied.
What are co-factors?
Many enzymes require the presence of certain ions or non-protein molecules before they will catalyse a reaction - such substances are called cofactors.
How do co-factors affect enzyme activity?
Cofactors change the shape of the active site so that the enzyme can combine with the substrate.
Without a cofactor the enzyme molecule is intact but cannot function.
What are co-enzymes?
Some cofactors are non-protein organic molecules. They are then called coenzymes.
- Many vitamins function as coenzymes.
Why must products of a reaction be continually removed?
Otherwise the rate of the reaction will slow because it becomes more difficult for the substrate molecules to contact the enzyme molecules.
