Enzymes Flashcards

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1
Q

Explain how a competitive inhibitor decreases the rate of an enzyme controlled reaction

A
  • 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
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2
Q

What is an enzyme?

A

a protein that acts as a biological catalyst, reducing the activation energy of a reaction, without being used up itself

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3
Q

How will an enzyme reduce the activation energy of a condensation reaction?

A

Holding the 2 reactants close together, minimising repulsion and allowing bonds to form

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4
Q

How will an enzyme reduce the activation energy of a hydrolysis reaction?

A

it will put strain on bonds making them easier to break

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5
Q

Describe the induced fit model of enzyme action

A
  • 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
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6
Q

Why can an enzyme only bind to one substrate?

A
  • 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
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7
Q

Describe the lock and key model of enzyme action

A

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

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8
Q

How could you measure the rate of enzyme action?

A

time taken for reactant to be used up OR for a product to form

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9
Q

How does increasing temperature impact enzyme activity?

A
  • increased kinetic energy
  • more frequent and successful collisions
  • more E-S complexes
  • further increases break bonds
  • denatures enzyme by changing shape of active site
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10
Q

How does changing pH impact enzyme activity?

A
  • 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
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11
Q

How does enzyme concentration impact enzyme activity?

A
  • 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
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12
Q

How does substrate concentration impact enzyme activity?

A
  • 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
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13
Q

What is one difference between the lock and key theory and the induced fit model of enzyme action?

A

in the induced fit model, the active site changes shape, but does not change in lock and key

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14
Q

What is one similarity between the lock and key theory and the induced fit model of enzyme action?

A

both form enzyme substrate complexes

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