3.1.4.2 - Many proteins are enzymes Flashcards
How do enzymes lower activation energy?
Holding substrates close together, reducing repulsion.
Applying pressure to bonds in the substrate, making them easier to break.
How does extreme pH affect enzyme activity?
Too high or low pH = H⁺ and OH⁻ ions disrupt ionic & hydrogen bonds → Changes active site shape → No enzyme-substrate complexes → Reaction slows or stops.
What is an enzyme
Protein which catalyses a reaction, lowering its activation energy
Describe what happens during an enzyme catalysed reaction
Enzyme collides with substrate and active site shape changes to fit substrate by induced fit. Forming an enzyme substrate complex. Which then breaks down to produce products leaving the enzyme unchanged
Describe competitive and non competitive inhibitors
Inhibitors reduce binding of enzyme to substrate
Competitive inhibitors - similar shape to substrate, bind to the active site, inhibition can be overcome by more substrates
Non - competitive inhibitors - bind o enzyme on a allosteric site, prevent formation of active site shape changing, cannot be overcome bu more substrates
Give an advantage of lactase and other digestive enzymes being located in the
plasma membranes of cells lining the small intestine, rather than being secreted into
the lumen of the small intestine.
Enzymes not lost (with gut contents)
More effective absorption
of products formed by these enzymes
Explain how raising the temperature to 35 °C affects carbohydrase activity;
- Increase in temperature = increases kinetic energy;
- Increases collisions so increases
formation of enzyme substrate complexes - Increases rate of breakdown of starch
Explain how decreasing the pH affects carbohydrase activity.
- Increases H+ ions
- Hydrogen / ionic bonds disrupted
- Changes shape of active site so active site so enzyme substrate complex no longer able to form
- Decreases rate of breakdown of starch
