Enzymes Flashcards
Explain how a competitive inhibitor decreases the rate of an enzyme controlled reaction
- Has a similar shape to the substrate which is specific to the enzyme’s active site
- The inhibitor is able to bind to the active site
- This prevents the enzyme from binding to the intended substrate - reducing the number of enzyme-substrate complexes formed
What is an enzyme?
a protein that acts as a biological catalyst, reducing the activation energy of a reaction, without being used up itself
How will an enzyme reduce the activation energy of a condensation reaction?
Holding the 2 reactants close together, minimising repulsion and allowing bonds to form
How will an enzyme reduce the activation energy of a hydrolysis reaction?
it will put strain on bonds making them easier to break
Describe the induced fit model of enzyme action
- An enzyme will bind to a substrate that has a shape complementary to that specific active site
- forming an enzyme-substrate complex
- the active site will change shape slightly to better fit the substrate molecule
Why can an enzyme only bind to one substrate?
- each enzyme has a different primary structure
- therefore they have different tertiary structures
- this means that the shape of the active site is different for each enzyme
- this active site is only complementary to 1 substrate, therefore any other substrate will not be able to form enzyme-substrate complexes as it would be unable to bind
Describe the lock and key model of enzyme action
The shape of the substrate is an exact fit the shape of the enzyme’s active site allowing it to fit into the active site
How could you measure the rate of enzyme action?
time taken for reactant to be used up OR for a product to form
How does increasing temperature impact enzyme activity?
- increased kinetic energy
- more frequent and successful collisions
- more E-S complexes
- further increases break bonds
- denatures enzyme by changing shape of active site
How does changing pH impact enzyme activity?
- each enzyme has optimum pH
- deviation will slow the rate of reaction as charges of amino acids are disturbed
- extremities will result in broken bonds and the enzyme becoming denatured
How does enzyme concentration impact enzyme activity?
- excess substrate, as enzyme concentration increases
- more enzyme molecules collide with substrate molecules
- rate of reaction increases.
- Once substrate concentration becomes limiting the rate of reaction with cease to increase further
How does substrate concentration impact enzyme activity?
- as substrate concentration increases rate of reaction increases
- more substrate available to fill the active sites.
Once the enzymes are working at maximum capacity the rate of reaction cannot increase further
What is one difference between the lock and key theory and the induced fit model of enzyme action?
in the induced fit model, the active site changes shape, but does not change in lock and key
What is one similarity between the lock and key theory and the induced fit model of enzyme action?
both form enzyme substrate complexes