Enzymes Flashcards
What is a catalyst?
a substance that increases the rate of a chemical reaction and is not changed by the reaction
What are enzymes?
proteins that are involved in all metabolic reactions, where they function as biological catalysts
Why are enzymes important in all living
organisms?
they maintain reaction speeds of all metabolic reactions (all the reactions that keep an organism alive) at a rate that can sustain life. Without enzymes, reactions are so slow to occur, that the cells would die from not being able to do life processes
Explain enzyme action with reference to: active site, enzyme-substrate complex, substrate and product
Enzymes are specific to one particular substrate as the active site of the enzyme, where the substrate attaches, is a complementary shape to the substrate. They fit together like a lock (enzyme) and key (substrate). When the substrate moves into the enzyme’s active site they become known as the enzyme-substrate complex. After the reaction has occurred, the products leave the enzyme’s active site as they no longer fit it and the enzyme remains unchanged and takes on another substrate.
What is a substrate?
the specific reactant on which an enzyme acts
What is an active site?
The groove in the enzyme that binds the substrate
What is an enzyme substrate complex?
a temporary molecule formed when the substrate binds to the enzyme
What are products?
The molecule that is produced by the chemical reaction catalyzed by the enzyme from the substrate
Are the enzymes altered by the reaction?
No they aren’t consumed or altered by the reaction and can be reused for more reactions
How does a protein get its shape?
The sequence of amino acids
When do enzyme reactions occur?
When the substrate and enzyme collide
What is denaturing?
when an enzyme loses its shape rendering it unable to bind to substrate
When an enzyme changes shape, it no longer works. Why?
Because the active site is the wrong shape for the substrate so they can no longer bind
Explain the effect of changes in temperature on enzyme activity in terms of kinetic energy, shape and fit, frequency of effective collisions and denaturation
At lower temperatures, there are fewer successful collisions because the enzymes and the substrates have less kinetic energy. When the temperature is increasing, the enzymes and substrates have more kinetic energy resulting in more successful collisions. At the optimum temperature, the enzymes work the fastest they can. Above the optimum temperature, there are more collisions but the active site becomes denatured by the high temperature and the active site and substrate are no longer complementary so there are fewer successful collisions
Explain the effect of changes in pH on enzyme activity in terms of shape and fit and denaturation
At extreme furthest from optimum pH, the enzymes are completely denatured and there’s no activity. The optimum pH depends on where the enzyme works in the body but it’s where the enzyme works the fastest. Above the optimum pH results in gradual loss in activity because the active site denatures and the substrate can’t bind to it.
