9. Enzymes Flashcards
Define Enzyme
An organic substance (usually a protein) that increases the speed of chemical changes without being altered or destroyed in the change; an organic catalyst.
Explain the lock-and-key theory
The lock-and-key model states that shape of the enzyme (the key) is always complementary to the shape of the substrate (the lock). Therefore, the two will fit exactly to form the enzyme-substrate complex.
Draw the lock-and-key model
Define Catabolic (degradation) Reaction
Reactions that break down large molecules into smaller ones.
Define Anabolic (synthesis) Reaction
Reactions that build up small molecules into bigger ones.
How does pH effect enzymes?
Change in pH also alter the shape of a enzyme’s active site. Each enzyme work bests at a specific pH value. The optimum pH for an enzyme depends on where it normally works.
What are the effects of temperature on enzymes?
Enzymes like to be at an otimal temperature. If the temperature is too low, there is not enough energy for the reaction to proceed. By increasing the temperature, the rate of reaction will increase because there is more energy for the reaction. After a certain temperature, the reaction will start to decrease rapidly to zero.
Define Denaturing
For an enzyme to become denatured it would have to exceed it’s capacity temperature which causes the enzyme shape to change (breaking bonds). They become not complimentary to the shape of the substrate and then there is less reaction as the temperature increases.
What are the effects of substrate concentration?
A limited concentration of substrate will limit the rate of reaction. As the substrate concentration increases, so does the rate of reaction, until the lack of available enzymes becomes the limiting factor.
Draw a simple graph of the effect of temperature.
Draw a denatured enzyme.
Draw a graph of the effect of substrate concentration.
What are the effects of enzyme concentration?
A limited concentration of enzyme will also limit the rate of reaction. The reaction starts to become limited because there are not enough enzymes to bind with all the substrates. I.e. there are no empty “spaces” (active sites) and too many substrate molecules.
Draw a simple graph of the effect of enzyme concentration.
What is the activation of enzymes?
Many enzymes require the presence of certain ions or non-protein molecules before they will catalyse a reaction. Suchh as cofactors and coenzymes.
Draw an activation of enzyme model.
Draw competitive Inhibition
Draw noncompetitive inhibition
