BY1: Enzymes

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Define Catalyst
A molecule which speeds up a chemical reaction, but remains unchanged at the end of the reaction
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Define Metabolism
all the chemical processes that take place in living organisms
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What is a Substrate?
the substance that an enzyme acts on
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Explain what is meant by the term denatured
the enzyme loses it's specific 3D shape of its active site so that it can permanently no longer catalyse reactions
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What is enzyme inactivation?
when an enzyme no longer works but the active site maintains its shape e.g. at very low temperatures
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What is inhibition?
Inhibition occurs when enzyme action is slowed down or stopped by another substance
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What is an immobilised enzyme?
an enzyme which is fixed or trapped on and inert matrix
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Define intracellularly
within the cell
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Define extracellularly
outside of the cell
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What is a biosensor?
the association of a biomolecule with a transducer, which produces an electrical signal in response to a substrate transformation.
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Describe the structure of an enzyme
Enzymes are a tertiary structure; the polypeptide chain is folded into a globular shape; hydrophillic R groups on the outside make it soluble; shape held together by H bonds, disulphide bridges andionic bonds.
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What is the induced fit model?
A substrate enters theactive site and forms temporary bonds, which cause the active shape to change slightly, like a hand going into a glove.
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What are three properties of an enzyme?
Specifity: each enzyme is specific to only one substrate; high turnover number: enzymes are extremely fast acting so can catalyse many reactions per second; lowers activation energy
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Define activation energy
Activation energy is the energy required to break existing chemical bonds inside molecules in order for a chemical reaction to move forwards
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How does an enzyme lower activation energy?
As the active site shape changes around the substrate, the shape changes stress some of the chemical bonds, causing them to break, hence reducing the energy required to initiate the reaction.
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What is a turnover number?
the number of substrate molecules processed per time unit by 1 enzyme
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What is the rate of reaction proportional to?
Enzyme concentration
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What is the Q10 number?
Rate of reaction at (x+10) degrees / rateof reaction at x degrees
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What will small changes in pH do to an enzyme?
Inactivate it
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What will large changes in pH do to an enzyme?
Denature it
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In general, what does an inhibitor do?
COmbines with an enzyme and either directly or indirectly prevents it from forming enzyme-substrate complexes
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What is a competitive inhibitor?
Has a molecular shape similar tothe substrate allowing themto enter and block the active site. They are in direct competition for the active site with the substrate.c
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Which competitive inhibitor takes the place of succinate in the enzyme succinatede hydrogenase?
Malonic acid
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How non-competitive inhibitors attach to an enzyme?
they bind to the enzyme at a site rather than the active site
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How do non-competitive enzymes change the active site of an enzyme?
Binding causes the overall shape of an enzyme to change, including the active site.
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Which non-competitive inhibitor attaches itself to cytochrome oxidase to inhibit respiration?
Cyanate
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How are enzymes encapsulated?
Alginate Beads
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What are the three main advantages of immobilised enzymes?
They are easily seperates from the product and do not contaminate the product; They are easily recovered for reuse; increased enzyme stability so that they withstand a greater range of pH and temperatures than 'free' enzymes.
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What disease can a biosensor detect?
Diabetes
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Other cards in this set

Card 2

Front

Define Metabolism

Back

all the chemical processes that take place in living organisms

Card 3

Front

What is a Substrate?

Back

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Card 4

Front

Explain what is meant by the term denatured

Back

Preview of the front of card 4

Card 5

Front

What is enzyme inactivation?

Back

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