Enzymes.

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What is an enzyme?
A biological catalyst.
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What do enzymes do?
They speed up the rate of reaction by lowering the activation energy needed for a chemical reaction.
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How do enzymes lower the activation energy?
They align the reactants through the formation of an enzyme substrate complex and stress the bonds within the molecule so they require less energy to break them.
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What is activation energy?
The minimum energy required for successful chemical reaction (breaking the bonds)
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What type of proteins are enzymes?
Gobular proteins because they has a specific tertiary structure.
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What makes an enzyme specific?
They have a specific and complementary active site to the substrate.
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What is the lock and key method?
Active site is specific and complementary to the substrate before and after it binds.
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What is the induced fit model?
Before the reaction the active site is not complementary to the substrate. Shape of the active site changes as the substrate binds (Enzyme Substrate Complex). This stresses the bonds distorting it leaving to a reaction with the substrate.
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What happens when enzymes are under high temperatures?
High temp increases kinetic energy=more collisions between the ES complex.Hydrogen and ionic bonds breaking between the R groups destroying the tertiary structure.Changes the shape of the active site+no longer complementary to substrate=fewer ESC.
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Describe the effect of pH on a enzymes (graph)
As you move away from the optimum pH, the rate of reaction decreases.
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Explain the effect of pH on enzymes.
pH alters from the optimum charge of the Rgroups of the amino acids are altered, causing a lose of tertiary structure as hydrogen and ionic bonds are broken.The active site changes shape and is no longer specific+complementary to substrate.Fewer ESC.
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What does a buffer do?
Adding a buffer keeps the pH the same.
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Diabetes mellitus is a disease that can lead to an increase in blood glucose concentration. Some diabetes need insulin injections. Insulin is a protein so it cannot be taken orally. Suggest why insulin cannot be take orally?
Because it would be broken down by enzymes, denature due to the pH andtoo large to be absorbed.
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What is pH?
The measure of hydrogen ion concentration.
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Describe the effect of substrate concentration on enzymes. (graph)
As the substrate concentration increases the rate of reaction increases and then levels off (use data to support)
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Explain the effect of substrate concentration on enzymes. (Substrate is the limiting factor)
As the substrate conc. increases the active sites are filled and the rate of reaction increases due to the more successful collisions between the active site+substrate. The substrate is no longer the limiting factor.
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Explain the effect of substrate concentration on enzymes. (Number of enzymes)
At high levels of substrate, there is no further rise in rate of reaction as enzyme substrate complexes active sites are filled. The number of enzymes is now the limiting factor.
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What is an inhibitor and what types are there?
An inhibitor is a substance which decreases the rate of reaction There are two types:Competitive and non competitive.
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What are competitive inhibitors?
They are a similar shape/ structure to the substrate allowing them to attach to the active site, but do not react.This prevents the substrate from binding,and slows the rate of reaction because there are fewer enzyme substrate complexes formed.
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How do competitive inhibitors recover the rate of reaction?
To overcome inhibition you add more substrate.
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What are non-competitive inhibitors?
They bind to a site away from the active site, called the allosteric site. This alters the shape of the active site so the substrate cannot fit. Fewer enzyme substrate complexes can be formed.
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Can non-competitive inhibitors overcome inhibition?
No.
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Card 2

Front

What do enzymes do?

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They speed up the rate of reaction by lowering the activation energy needed for a chemical reaction.

Card 3

Front

How do enzymes lower the activation energy?

Back

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Card 4

Front

What is activation energy?

Back

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Card 5

Front

What type of proteins are enzymes?

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