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

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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

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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
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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
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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
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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
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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
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