Enzymes Revision

  • Created by: ElishaG
  • Created on: 20-02-17 20:10
What are enzymes?
Globular proteins with a specific tertiary structure, which catalyse metabolic reactions in living organisms.
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What are intracellular enzymes?Give an example.
They're inside of cells e.g. catalase and ATP synthase.
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What are extracellular enzymes?Give an example.
Outside of cells but inside of body, e.g. amylase and trypsin.
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Describe the lock and key theory.
1)Shape of enzymes and substrates are complementary.2)Have complementary charges so are attracted to each other, when enzyme and substrate bind, enzyme-substrate complex forms.3)Enzyme-product complex is produced.4)Products are released.
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What do we need in order for the enzyme and substrate to bind?
1)Activation energy needs to be met.2)Need successful collisons.
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Why are the products released?
Because the products and enzyme are no longer complementary.
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Describe the induced fit theory.
1)Active site and substrate are complementary, like a hand and glove-the glove changes shape.2)Bonds are easier to break because when the substrate and enzyme join pressure is put on the bond.
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Explain the term biological catalyst.
Something that speeds up chemical reactions without affecting the results of the reaction and without being used up.Lowers activation energy.
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Suggest how you would measure the rate of a reaction.
1)Measure rate at which reactants are used or products are formed.
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When an enzyme is at its optimum PH/Temperature, what does this mean?
It is when the enzyme works its best.
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What circumstances does an enzyme denature and what happens to it?
1)When the temperature/PH is too high.2)Its active site has changed shape- it is irreversible.
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What is a limiting factor?
Something that slows the rate of the reaction and stops the rate increasing.
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When there is a limiting factor, how can the substrate concentration be increased?
More enzymes can be added.
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What are inhibitors?
Any substance or molecule that slows down the rate of an enzyme controlled reaction by affecting the enzyme molecule.
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What are the two types of inhibitor?
1)Competitive inhibitor.2)Non-competitive inhibitor.
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Describe how competitive inhibitors effect rate of reaction.
1)Rate decreases.2)Inhibitor and substrate have similar shape/structure.3)Both fit into active site as they're complementary.4)Substrate molecule is blocked from entering active site.5)Fewer enzyme-substrate complexes form.
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Describe how non-competitive inhibitors effect rate of reaction.
1)Rate decreases.2)Fits into allosteric site.3)Active site changes.4)Substrate no longer complementary to active site.5)Enzyme-substrate complex doesn't form.
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What is a cofactor?
Any substance that must be present to ensure enzyme controlled reactions take place at the appropriate rate.They're part of an enzymes prosthetic group.
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What may cofactors be?
1)Charged metal ions (activators) that temporarily bind to active site.2)Organic molecules, usually vitamins or coenzymes made from vitamins.Temporarily bind with enzyme-substrate complex.
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Are chloride ions an activator or coenzyme? Describe its role.
Activator. Amylase enzymes must contain Cl- to adopt their functional shape, allowing enzyme to hydrolyse amylose to maltose.
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Are calcium ions an activator or coenzyme?Describe its role.
Activator.Thrombin enzymes responsible for blood clotting.Enzyme needs Ca2+ to form effective clot.
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Is Coenzyme A an activator or coenzyme?Describe its role.
In respiration, substrate pyruvate is broken down to acetyl, which is very reactive. Coenzyme A helps remove it from active site in a stable manner.
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Other cards in this set

Card 2

Front

What are intracellular enzymes?Give an example.

Back

They're inside of cells e.g. catalase and ATP synthase.

Card 3

Front

What are extracellular enzymes?Give an example.

Back

Preview of the front of card 3

Card 4

Front

Describe the lock and key theory.

Back

Preview of the front of card 4

Card 5

Front

What do we need in order for the enzyme and substrate to bind?

Back

Preview of the front of card 5
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