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Enzymes Key Question: What are enzymes and how do they work?
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Enzymes What are they? Why do we need them?
Can you name some examples?
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Enzymes Proteins that catalyze chemical reactions in organisms
Properties
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Enzymes Globular proteins that catalyse chemical reactions organisms
Specific Properties
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Enzymes Globular proteins that catalyse
chemical reactions in organisms Specific Properties Increase rate of the chemical reaction
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Enzymes Globular proteins that catalyse
chemical reactions in organisms Specific Properties Increase rate of the reaction Unchanged at the end of the reaction
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Enzymes Globular proteins that catalyse chemical reactions in living organisms Specific Properties Increase rate of the reaction Unchanged at the end of the reaction We need them
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Enzymes Globular proteins that catalyse chemical reactions in living organisms Specific Properties Increase rate of the reaction Unchanged at the end of the reaction Reactions too slow to maintain life We need them Can’t increase temperatures/pressure in cells (fatal)
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The enzyme binds to the substrates by its active site
Enzymes Are Proteins The enzyme binds to the substrates by its active site The active site is a pocket formed by the folding of the protein where the substrates bind.
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Active site The active site involves a small number of key chemicals that actually bind the substrates
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How do enzymes work?
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An Example
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An Example Sucrose + H2O Glucose + Fructose
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An Example Substrates Sucrose + H2O Glucose + Fructose Products
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For a reaction to occur the sucrose
and water would have to collide with enough energy to break and form bonds
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For a reaction to occur the sucrose
and water would have to collide with enough energy to break and form bonds This is the activation energy
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Sucrose + H2O Glucose + Fructose + + Substrates Products
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Energy Progress of reaction
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Energy Substrates Progress of reaction
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Energy Substrates Products Progress of reaction
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Energy Progress of reaction High energy intermediate stage Substrates
Products Progress of reaction
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= The Activation energy
The minimum amount of energy needed to start the reaction, leading to the formation of a high energy intermediate = The Activation energy
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Activation energy Energy Progress of reaction High energy intermediate
Substrates Products Progress of reaction
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Activation energy Enzymes reduce the height of the energy barrier
High energy intermediate Activation energy Enzymes reduce the height of the energy barrier Energy Substrates Products Progress of reaction
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