1.7, 1.8, 1.9: Enzyme Action Flashcards
Enzymes
Speed up chemical reactions by acting as biological catalysts
Intracellular
within cells
Extracellular
outside cells
What are enzymes made of
Proteins
Activation energy
A certain amount of energy is needed to be supplied to the chemicals before the reaction will start
Enzymes … the activation energy
lower
What does the active site bind to
what does it form
substrate
enzyme-substrate complex (ESC)
reasons why ESC lowers actiation energy
= substrate molecules attached to the enzyme stay closer together which reduces any repulsion so they can bond more easily
=fitting into the active site puts a strain on the bonds in the substrate so they break up more easily
Older enzyme model
Lock and key model
New evidence to alter view of lock and key model
ESC changes shape slightly to complete the fit = locks the substrate even more tightly into the enzyme
More recent enzyme model
Induced fit model
Induced fit model
Helps to explain why enzymes are so specific and only bond to one substrate.
The substrate makes the active site change shape
Tertiary structure of enzyme determines…
the shape of the active site
Different enzymes have
different tertiary structures = different shaped active sites
Alteration to tertiary structure of an enzyme means…
Shape o the active site changes
substrate won’t fit
no ESC
enzyme can’t carry out its function
What affects the tertiary structure of enzymes
pH or temp changes
How does a gene mutation affect the tertiary structure of the enzyme produced?
Gene mutation = amino acids sequence changes = primary structure different = tertiary structure different
Competitive inhibitors
shape
Have a similar shape to substrate molecules
Competitive inhibitors
how do they work
Compete with substrate molecules to bind to the active site but no reaction occurs and the active site is blocked
Competitive inhibitors
Amount of enzyme inhibited
depends on relative concentrations of inhibitors and substrates
Non-competitive inhibitors
Non-competitive inhibitors molecules bind to the enzyme away from its active site
Non-competitive inhibitors
how do they work
Causes active site to change shape so substrate molecules can’t bind to it
Non-competitive inhibitors
Amount of enzyme inhibited
Increasing substrate conc. won’t affect the ROR. = enzyme activity will still be inhibited
Measuring the rate of an enzyme controlled reaction
2 methods
Measure hoe fast the product is made
Measure how fast the substrate is broken down
Enzyme controlled reaction results show in
line graphs
Calculating the initial rate of reaction
Tangent
