04. Enzymes Flashcards
What is an enzyme?
a protein biological catalyst, that speeds up chemical reactions by lowering the activation energy of reactions.
Draw a 3-part enzyme diagram.
Explain what determines the structure of the active site.
Because the enzyme (protein) is made from a sequence of amino acids then the R groups from these determine the bonds that will form. Therefore leading to the overall 3D structure, including the active site.
Define metabolism
The sum total of all chemical reactions occurring in an organism
What does a synthesis reaction mean?
Two substrates combine to form one product
What does a decomposition reaction mean?
One substrate breaks down to form two products
What factors affect the rate of enzyme reactions?
Temperature
pH
Enzyme concentration
Substrate concentration
Competitive inhibitors
Non-competitive inhibitors
Draw an enzyme Rate of reaction vs temperature graph
Explain why the enzyme controlled reaction is low at a low temperature
Because the enzymes are inactive
Then there is less kinetic energy and it is less likely to have successful collisions between enzymes and substrate
Therefore less enzyme-substrate complexes will form, less products will form and there is a lower rate of reaction
Define optimum temperature
Temperature where the enzyme works best and there is the most enzyme substrate complexes forming.
Explain why the enzyme controlled reaction is low at a high temperature
Because there is too much kinetic energy the enzyme’s denature
Then the 3D structure of the active site has changed shape so it is no longer specific and complementary to the substrate
Therefore less enzyme-substrate complexes will form and there will be less products and a lower rate of reaction.
Draw an enzyme Rate of reaction reaction vs pH graph
Explain why the enzyme controlled reaction is low at a low pH
Because the pH is too low the enzyme’s denature
Then the 3D structure of the active site has changed shape so it is no longer specific and complementary to the substrate.
Therefore less enzyme-substrate complexes will form and there will be less products formed and a lower rate of reaction.
Explain why the enzyme controlled reaction is low at a high pH
Because the pH is too high the enzyme’s denature
Then the 3D structure of the active site has changed shape so it is no longer specific and complementary to the substrate.
Therefore less enzyme-substrate complexes will form and there is less products and a lower rate of reaction.
Draw an enzyme rate of reaction vs enzyme concentration (assuming unlimited substrate concentration)
Draw an enzyme rate of reaction vs substrate concentration graph
Explain how a competitive inhibitor lowers the rate of an enzyme controlled reation
Because competitive inhibitors are specific and complimentary to the active site of the enzyme, then they bind to the active site instead of the substrate. Therefore less enzyme-substrate complexes form, less products and the rate of reaction is lower.
Explain how a non-competitive inhibitor lowers the rate of an enzyme controlled reaction.
Because non-competitive inhibitors bind to the allosteric site (not the active site), then the 3D structure of the active site changes shape so that it is no longer specific and complimentary to the substrate. Therefore less enzyme-substrate complexes form, less products and the rate of reaction is lower.
Draw a 3-part enzyme diagram showing competitive inhibition
Remember to always draw the normal 3-part enzyme diagram first.
Draw a 3-part enzyme diagram showing non-competitive inhibition
How can the rate of reaction be increased in the presence of a competitive inhibitor?
Increase substrate concentration
What is an enzyme-substrate complex?
When the enzyme and substrate have successfully collided and bound together
What factors cause an enzyme to denature?
High temperatures (above the optimum), high or low pH (above or below the optimum)
Why does the graph plateau in an enzyme rate of reaction vs substrate concentration graph?
Because all enzyme active sites are occupied with substrate
Then the maximum number of enzyme substrate complexes are already forming each second
Therefore the reaction rate plateaus and cannot increase regardless of an increase in substrate.
