8.1 Flashcards
what are cycles?
- where a start molecule is changed over a series of reactions and reformed
- allowing continuous pathway
what are chains?
- where a start molecule changed over a series of reactions to form an end molecule
what are enzymes?
proteins that speed up the rate of reactions by lowering the activation energy
how do enzymes lower the activation energy?
by colliding with substrates at the active site that have
1. a complementary shape and charge
2. the correct orientation
3. sufficient energy
what are the 2 binding of substrate theories?
- lock and key mechanism
- induced fit mechanism
describe the lock and key mechanism
- states that the active site has an exact fit with the substrate
- it is the binding of substrates with complementary shape and charge
describe the induced fit mechanism
- the binding of substrates with complementary shape and charge
- states that the active site has an approximate fit with the substrate
- molds to fit the substrate as it successfully collides
- it is regarded to be more accurate
why do enzymes need to be inhibited at times?
- to control the metabolic pathway
- prevent unnecessary production
what are the 2 types of inhibition?
- competitive
- non-competitive
describe the process of competitive inhibition
- the inhibitor molecule is similar in shape and charge to the substrate
- as a result, it is able to bind to the active site and occupy it for a period of time
- this therefore, slows down the reaction because it prevents the substrate from binding and undergoing catalysis
what is an ib example of a competitive inhibition
the conversion of succinate to fumarate
describe the process of the conversion of succinate to fumarate
- malonate is the competitive inhibitor that binds to the enzyme
- this prevents succinate from binding
describe the process of non-competitive inhibition
- the inhibitor molecule binds to a secondary site on the enzyme (allosteric site)
- binding to this site triggers a change in enzyme conformation
- resulting in the change in active site shape
- this means that it can no longer mold to fit the substrate and thus completely prevents the reactions from occurring
what is the ib example for a non-competitive inhibition?
the conversion of triose phosphate to pyruvate
describe the process of the conversion of triose phosphate to pyruvate
- alanine binds to the allosteric site of pyruvate kinase
- prevents triose phosphate from binding
what is the end-product inhibition and why is this type of non-competitive inhibition useful?
- when the end product of a chain inhibits the enzyme involved in the first reaction
- it is very effective at controlling the concentration of all the molecules in the pathway
describe the rate of reaction during competitive inhibition
- rate increases at a slower rate due to blocking of the active site
- as substrate concentration increases, it begins to outcompete the inhibitor for the active site
- therefore, it is able to reach the same maximum rate at a high substrate concentration
describe the rate of reaction during non-competitive inhibition
- rate increases at a much slower rate due to the changes in the active site of multiple enzymes
- as substrate concentration increases, unaffected enzymes collide more frequently with the substrate
- however, this means only a certain number of enzymes reach maximum rate
- which will be lower than that of competitive inhibition
