Enzymes Flashcards
Enzymes are biological catalysts. What does that mean?
They lower the activation energy of the reactions they catalyse.
Draw the induced fit model:
Induced fit model
What dictates the enzyme’s active site shape?
Tertiary structure
How are enzymes specific?
Their active site shape is only complementary to a particular substrate.
How does enzyme concentration affect rate of reaction?
Increasing enzyme conc will increase rate of reaction. But, if the amount of substrate is limited there comes a point when there’s too many enzymes to deal with the substrates and so adding more has no effect.
How does substrate conc affect rate of reaction?
The higher the substrate conc, the faster the reaction until saturation point where all active sites are saturated and so no further reactions can take place.
How does conc of competitive inhibitors affect rate of reaction?
If there’s a high concentration of inhibitor then the rate of reaction will decrease as they block the active sites up until a point if there’s a higher conc of substrate.
How does the conc of non-competitive inhibitors affect the rate of reaction?
Increasing concentration of non-competitive substrates decreases rate of reaction and increasing conc of substrate won’t make any difference.
How does pH affect rate of reaction?
Above and below the optimum, the bonds that hold the tertiary structure together get disrupted and the enzyme becomes denatured changing the active site shape. This decreases rate of reaction.
How does temperature affect rate of reaction?
Rate increases until optimum temperature as at high temperatures the enzyme vibrate and break the bonds holding the tertiary structure in place. Denature and change active site shape reducing rate of reaction.
What is the difference between the Lock and Key model and the Induced Fit model?
Lock and Key model didn’t show how the active site slightly changes shape to accommodate the substrate as pressure is placed upon the bonds to change the shape.
Which reactions do enzymes assist in?
Respiration, digestion, production of collagen, etc.
How can you measure the rate of an enzyme-controlled reaction?
- Set up boiling tubes containing same vol and conc of hydrogen peroxide. To keep pH constant, add equal vols of buffer solution to each tube.
- Set up a trough of water, upside down measuring cylinder, delivery tube and bung.
- Put each boiling tube in a water bath set to different temps along with another tube containing catalase. Wait 5 mins.
- Use pipette to add same vol and conc of catalase to each boiling tube. Quickly attach bung and delivery tube.
- Record how much oxygen is produced in the first min. Use stopwatch.
- Repeat at each temp 3 times, find a mean.
- Calculate mean rate of reaction.
