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Enzymes
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Enzymes Enzymes are proteins.
They are catalytic molecules. That is, they speed up specific reactions without being used up in the reaction.
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Lock & Key Each enzyme is highly selective about its substrate.
The lock and key mechanism: The lock is the enzyme The key is the substrate The substrate binds the enzyme at the active site.
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What affects an enzyme’s speed (rate of reaction)?
1. Temperature: Increase temperature = increased reaction rate (speed) Decrease temperature = decrease reaction rate (speed)
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Denature: To inactivate the enzyme so it no longer functions.
High temperatures will change the shape of the active site and the substrate can’t bind anymore.
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What affects an enzyme’s speed (rate of reaction)?
2. pH: an acid will decrease the rate of reaction If the acid is strong enough it will denature the enzyme.
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How much power? Activation energy is the minimum amount of energy that molecules must collide with so they can reach the transition state. Then they can react spontaneously.
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Meet some enzymes... Carbonic anhydrase speeds up the process by which CO2 leaves the cells and enters the bloodstream.
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Meet some enzymes... Lipase, which is made in the pancreas, function is to digest lipids in the small intestines.
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Meet some enzymes... RNA polymerase facilitates the process of RNA transcription (the making of new RNA).
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What do they have in common?
Carbonic anhydrase Lipase RNA polymerase ALL enzymes end in –ase!
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Missing them... Some disease are caused by the inability to create an enzyme, or a faulty enzyme. Tay-Sachs is a disease that is caused by the lack of Hexosaminidase A, which breaks down lipids in the brain and other nerve cells.
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Missing them... Phenylketonuria (PKU) is a disease caused a defective enzyme called phenylalanine hydroxylase (PAH), which breaks down the amino acid phenylalanine.
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Missing them... Lactose intolerance (AKA Lactase Deficiency) is a disease caused by the lack of the enzyme lactase which breaks down the milk sugar called lactose.
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