Enzymes Flashcards
What do enzymes do?
Act as biological catalysts and catalyse metabolic reactions.
What makes enzymes highly specific?
Their tertiary structure.
How do enzymes catalyse reactions?
Lower the activation energy, meaning that the reaction can happen at lower temperatures, increasing the rate of reaction.
What do enzymes do to substrates?
Form enzyme substrate complexes. Fitting into the active site out strain on the binds in the substrate allowing it to break up more easily.
Describe the lock and key model.
Substrate and enzymes active site are complementary to one another.
Describe the induced fit theory.
Active site and substrate already fit but the substrate causes changes in the active site to make them complementary.
Enzymes properties in relation to tertiary structure.
Specific, usually catalysing only one reaction due to their complementary active site determined by the tertiary structure (which is determined by primary structure).
Describe how temperature increase affects the enzyme action.
Molecules have more kinetic energy so move faster creating more collisions, molecules vibrate more, a over a certain point this breaks the bonds that maintain the shape, active site changes making the substrate no longer complementary and the enzyme has been denatured.
Describe how pH affects enzyme activity.
Enzymes have an optimum pH value, above and below this the H ions in acids and the OH in alkalis break the ionic and hydrogen bonds altering the active site, denaturing the enzyme.
Describe the affect of enzyme concentration on enzyme activity.
More enzyme molecules, the more likely a collision is to occur and form ES complexes, increasing the rate of reaction. However, this stops when there are no more substrates to collide with.
Describe the affects of substrate concentration on enzyme activity.
The more substrate molecules the more likely collisions are to occur forming ES complexes, up until a saturation point where all the enzymes are used up and the substrate concentration makes no difference. Substrate concentration decreases over time so as does the rate of reaction.
Describe competitive inhibition.
Similar in shape to substrate molecule and compete with them to bind to the active site, blocking it from the substrate. The higher the concentration of substrate the higher the chance of collisions - increasing ror.
Describe non-competitive inhibition.
Binds to the enzyme away from the active site, causing it to change shape making the substrate no longer complementary.
What is a buffer solution?
A solution that is able to resist changed on pH.
