Chapter 9: Enzymes

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An enzyme has a cleft in its surface called the ___ ___.
Active Site.
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What is 'Induced Fit'?
The arrival of the substrate molecule causes a change in the shape of the enzyme.
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Interaction between the R groups of the enzyme and the atoms of the substrate can break, or encourage the formation of, bonds in the __ molecule.
Substrate
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Define 'Activation Energy'
In many reactions, the substrate will not be converted to a product unless it is temporarily given some extra energy. The initial energy a substrate needs in order for it to change into a product.
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What is it known as if the enzyme is working at its quickest possible rate?
Vmax.
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Explain how an enzyme denatures when temperature increases.
The speed of movement of the substrate and enzyme continues to increase. Above a certain temp., the structure of the enzyme molecules vibrates so much that some of the bonds holding them together break (H+) Enzyme loses its shape activity=denatured
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pH is a measure of the concentration of hydrogen ions in a solution; lower the pH, higher concentration of H+ ions. Hydrogen ions can interact with the _ Groups of the amino acids, influencing how they bond and affecting tertiary structure.
R
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Define 'Inhibitor'
A substance that slows down or stops an enzyme-controlled reaction. Reduces the rate of an enzyme-catalysed reaction.
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What is 'competitive inhibition'?
Inhibition in which an enzyme inhibitor has a similar shape to the substrate molecule, and competes with it for the active site.
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Inhibitors that can seriously disrupt enzyme-controlled reactions can act as ___ ____, preventing vital chemical reactions that take place in the body.
Metabolic poisons
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Many enzymes require the presence of another substance in order to function. What are these called?
Cofactors (for simple molecules or inorganic ions) and coenzymes (larger molecules). Work by briefly binding to an enzyme.
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What do cofactors and coenzymes do?
Sometimes alter the shape of the enzyme so that it can bind more effectively with its substrate, and sometimes help the enzyme to transfer a particular group of atoms from one molecule to another.
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Enzymes are ___ proteins.
Globular.
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What is a cofactor? Give an example
Non-protein substance that is needed to allow an enzyme to work e.g. amylase works when chloride ions are present.
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What is a coenzyme? Give an example
Small organic non-protein molecules that bind to the active site before or during the reaction. It can be a permanent part of the enzyme known as the prosthetic group. Vitamin B makes a coenzyme used in respiration.
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Define Enzyme
Globular proteins with a specific active site which can bind substrates to them to catalyse reactions in the body and other organisms. They have a tertiary structure.
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Proteins are required in large amounts in the diet whereas vitamins and minerals are only required in small amounts. Suggest why.
Cofactors are being recycled again and proteins are used for other purposes other than enzymes.
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Is competitive inhibition reversible or not?
Reversible because it can be reversed by increasing the concentration of substrate.
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What is meant by non-competitive inhibition?
In which an enzyme inhibitor does not resemble the substrate and it binds with the enzyme molecule at a place other than its active site. It can seriously disrupt normal arrangement of hydrogen bonds holding the enzyme's shape.
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Is non-competitive inhibition irreversible or reversible?
Both, depending on whether the inhibitor bonds briefly or permanently with the enzyme.
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Other cards in this set

Card 2

Front

What is 'Induced Fit'?

Back

The arrival of the substrate molecule causes a change in the shape of the enzyme.

Card 3

Front

Interaction between the R groups of the enzyme and the atoms of the substrate can break, or encourage the formation of, bonds in the __ molecule.

Back

Preview of the front of card 3

Card 4

Front

Define 'Activation Energy'

Back

Preview of the front of card 4

Card 5

Front

What is it known as if the enzyme is working at its quickest possible rate?

Back

Preview of the front of card 5
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