How many of these are naturally occurring in proteins?
20
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What are the four groups around the central carbon of an amino acid?
Amino group (-NH2). Carboxyl group (-COOH). Hydrogen atom (H). R(side) group - A variety of different chemical groups, each amino acids has a different R group.
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What is the name of the bond formed between two amino acids during a condensation reaction?
A peptide bond
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Where does the water molecule come from during the condensation reaction?
The OH from the carboxyl group on one amino acid with the hydrogen on another
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What is the name of the process where many amino acids are joined together by a series of condensation reactions?
Polymerisation
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What is the molecule that is formed from this called?
Polypeptide
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What is this sequence of amino acids called?
The primary structure
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What does the primary structure of a protein determine?
Its ultimate structure and therefore its function
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So what happens if you change one amino acid in the primary structure sequence?
The final protein may stop being able to carry out its function, so the structure of a protein is extremely specific. Changing the shape will cause it to function less well or differently
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What are the groups on either side of every peptide bond?
-NH group and -C=O group
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Why is this important?
The H on the -NH has an overall positive charge and the O of the -C=O group has an overall negative charge. These readily form hydrogen bonds which cause the chain to be twisted into a 3D shape
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What is this 3D shape known as?
The secondary structure
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Give two examples of secondary structure names
Alpha helix and beta pleated sheet
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Describe the tertiary structure
The secondary protein structure can be twisted and folded to give a more complex and more specific
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Name the bonds that hold the tertiary structure together
Disulphide bridges, ionic bonds and hydrogen bonds
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Where do the ionic bonds form?
Between any carboxyl and amino groups that are not involved in peptide bonds
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When do quaternary structures of proteins form?
When multiple polypeptide chains link together, it can also contain prosthetic (non protein) groups.
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What determines the final 3D structure?
The original sequence of amino acids
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What is the main test for proteins and what does it detect?
The Biuret test which detects peptide bonds
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How do you carry out the Biuret test?
Place a sample (in solution) in a test tube and add an equal amount of sodium hydroxide. Then add very dilute copper (II) sulphate solution and mix gently. If it turns purple then it indicates the presence of peptide bonds
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Other cards in this set
Card 2
Front
What si the monomer unit of a polypeptide?
Back
An amino acid
Card 3
Front
How are proteins formed?
Back
Card 4
Front
How many proteins have been identified?
Back
Card 5
Front
How many of these are naturally occurring in proteins?
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