Enzyme Flashcards
1
Q
What are enzymes
A
- tertiary structuere proteins and so are a very specific 3d shape
- includes active site held by peptide , hydrogen, ionic and disulphide bonds
2
Q
What is the locke and key theory
A
- in this theory of enzyme action a successful collision has the substrate fit exactly into active site of the enzyme forming an enzyme subtrate complex
- reaction occurs and products are release
- enzyme remains unchanged at the end of the reaction
3
Q
What is the induced fit theory
A
- alternative theory of enzyme action
- lysozyme is propoed to function in this way
- active site and substrate are not fully complementary in shape
- reactive groups in theses areas align and the substrate forces it way into the active site
- both areas change structure slightly the bonds in the substrate weakens ad the reaction occurs at a lower activation energy
4
Q
What are intracellular enzymes
A
- these work inside cells
5
Q
What are extracellular enzymes
A
- secreted from cells for use outside the cell
6
Q
How does low temperature affect enzymes
A
- at low temperatures there is a low kinetic energy and so few successful collisions where the substrate i able to enter the active site of the enzyme and form products
7
Q
How does high temperatures till opimum affect enzymes
A
- as the temperature increases the kinetic energy increases
- more collissions and the enzyme subsstrate complexes formed per unit of time leading to increased producct
- continues up to an optimum temperature
8
Q
How does temperatures above optimum affect enzymes
A
- kinetic energy increases
- vibrations in enzymes weaken some bonds holding tertiary structure of active site together
- active site loses the shape and substrate is no longer complementary to active site no further enzyme substrate complexes can be made and enzyme said to be denatured
9
Q
How does substrate concentration affect enzymes
A
- as enzyme reaction relies on successful collissions between enzymes any increase in substrate concentration will increases collisions and rate of reaction
- low substrate concentrations it is this factor that is limiting the rate of reaction increaseing the substrate concentration increase the rate of raction
- at some point any further increase in substrate concentration has no effect as it platus as all the enzymes have full active sites at any one time
- enzyme concentration is now the limiting factor
10
Q
What are competitive inhibitors
A
- are complementary in shape to the active site of the enzyme
- therfore prevent the formation of enzyme substrate complexes by blocking the active site
- do not bind permanently
11
Q
What are non competitive inhibitors
A
- bind to the enzyme away from the active site at the allosteric site
- alters the shape of the active site so no enzyme substrate complexes can be formed
- some inhibitors bind reversible others bind irreversibly
12
Q
What do enzymes do
A
- enzymes are catalysts whcih mean they lower the activation energy of reactions but remain unchanges in the reaction
13
Q
How does pH affect enzymes
A
- most enzymes have an optimum pH
- small changes from the optimum either above or below optimum pH make small reversible changes in the enzyme reducing efficiency
- large changes in ph can disrupt ionic and hydrogen bonds in the enzyme causing permanenet changes to the shape of the active site
- prevent the formation of enzyme substrate complexes
- denaturing the enzyme
14
Q
How does enzyme concentration affect enzymes
A
- assuming excess substrate any increase in enzyme concentration increases the rate of reaction as more active sites are available for reactions
15
Q
What is metabolism
A
- anabolic reactions - building up molecule
- catabolic reaactions - breaking down of molecules
- catalysed by enzymes
