A compund made of amino acids linked by peptide bonds
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Which functional group does an amino acid contain? (2)
carboxyl group, amino group
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What is an amino acid? (1)
the monomer of polypeptides
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What is an alpha amino acid? (1)
An amino acid with both functional groups attached to the same carbon.
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What is the general formula of an alpha amino acid? (1)
C2H4O2R
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Define amphoteric. (1)
A substance with both acidc and basic properties.
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Which part of the amino acid has acidic properties? Why? (2)
The Carboxyl group because it can donate a proton
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Which part of the amino acid has basic properties? Why? (2)
The amino group because it can accept a proton
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What is a zwitterion? (3)
A dipolar ionic form of an amino acid that is formed by the donation of a hydrogen ion from the carboxyl group to the amino group. Because both charges are present, there is no overall charge
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How does a zwitterion form? (2)
A proton is transferred from the acid carboxyl group to the basic amine group
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What is the isoelectric point? (1)
The pH at which the amino acid extists as a zwitterion
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What happens at a pH that is more acidic than the isoelectric point? (2)
The amino acid forms a positively charged ion; the acid behaves as a bas and accepts a proton from the acid
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What happens at a pH that is more alkaline than the isoelectric point? (2)
The amino acid forms a negatively charged ion; the acid donates a proton to the base
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What is a dipeptide? (1)
2 amino acids joined by a peptide bond
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What type of reaction joins 2 amino acids together? (1)
Condensation reaction
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What is released during a condensation reaction? (1)
Water (or any small molecule i.e. HCl)
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What is the formula of the peptide linkage? (2)
O=C-N-H
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Define condensation reaction. (3)
A reaction where 2 small moleules react together to form a larger molecule with the elimination of a small molecule like water
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What is hydrolysis? (2)
The breaking down of a reaction with water. Hydrolysis can be catalysed by acid or alkali
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Why do the acid/alkali have to be in aqueous form during hydrolysis? (1)
Because a water molecule is needed to break each peptide bond
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What are the conditions and reagents required for acid hydrolysis? (4)
Heated under refulx, 6 mol/dm3, HCl, for 24 hours
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What charge do the amino acids have once acid hydrolysis has taken place? Why? (2)
Positively charged due to the presence of H+ ions from the acid
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What are the conditions and reagents for alkaline hydrolysis? (2)
Aqueous NaOH, just above 100 degrees
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What is the polypeptide chain broken down into during alkaline hydrolysis? (2)
Amino acids in the form of sodium salts
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Other cards in this set
Card 2
Front
Which functional group does an amino acid contain? (2)
Back
carboxyl group, amino group
Card 3
Front
What is an amino acid? (1)
Back
Card 4
Front
What is an alpha amino acid? (1)
Back
Card 5
Front
What is the general formula of an alpha amino acid? (1)
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