PL 2 - Kinetics Flashcards
1
Q
What does a rate vs. substrate concentration graph look like for an enzyme-catalysed reaction?
A
Curved concave graph, positive gradient slowly decreasing
2
Q
What is the order with respect to the substrate at low and high concentrations?
A
Low concentrations: The order with respect to the substrate is 1
High concentrations: The order with respect to the substrate is 0
3
Q
Why are enzymes specific?
A
- Enzymes are proteins with tertiary level structure and hence have a specific 3D shape
- Enzymes have an active site which is highly specific and binds to complementary substrate only (forming an enzyme-substrate complex), allowing the reaction to occur
4
Q
How is enzyme activity affected by temperature?
A
- As temperature increases, enzymes and substrate have more kinetic energy
- Therefore there are more frequent and successful collisions, forming more enzyme-substrate complexes
- Rate of reaction increases
5
Q
What happens to the enzyme if temperature is too high?
A
- The enzyme becomes denatured
- Some hydrogen bonds and other tertiary structure bonds are broken/altered
- Hence the tertiary structure of the enzyme is different, along with the shape of its active site
- Active site is no longer complementary to the substrate; it cannot bind to form enzyme-substrate complexes
- Rate of reaction decreases
6
Q
Why are enzymes sensitive to pH?
A
- All enzymes have an optimum pH
- Anything outside this range will result in a lower enzyme activity
- A wildly different pH may alter tertiary structure bonds etc. and denature the enzyme, decreasing rate of reaction
7
Q
What is competitive inhibition?
A
- A competitive inhibitor has a similar shape/structure to the substrate
- It competes with the substrate for the active site of the enzyme, preventing it from binding
- This lowers the number of enzyme-substrate complexes formed, decreasing rate of reaction