Amino acids
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What functional groups does an amino acid contain?
Amino group and carboxylic acid group
Amino acids can combine in what type of reaction?
A condensationreaction
If 2 amino acids combine what is produced?
A dipeptide
If 2 different types of amino acids combine what will be produced?
2 different types of dipeptide
What is produced when more than 2 amino acids combine?
A polypeptide which leads to protein formation
What does R represent in… Glycine (2-aminoethanoicacid) Alanine (2-aminopropanoicacid) Serine (2-amino-3-hydroxypropanoicacid)
Glycine- H Alanine- CH3 Serine- CH2OH
What is a primary protein structure?
The precise sequence of amino acids in the protein chain - many sequences with different amino acids
What is. Secondary protein structure
How parts of the protein fold up to form an alpha helix (held in shape by hydrogen bonds involving peptide link) or a beta pleated sheet (paper shape stabilised by hydrogen bonds between amino acids in different polypeptide chains) Results in hydrogen bonding Occurs between N-H and C=O groups of polypeptide chains
What is a tertiary protein structure
Proteins as a whole and the way in which alpha helices and beta pleated sheets of protein fold with respect to eachother This structure is held together by interactions eg Intramolecular- covalent and ionic bonds Intermolecular - VDW and H bonds
Draw acids hydrolysis of peptide/amide link
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Draw alkaline hydrolysis of peptide/amide link
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What do amino acids predominantly exist as and what are these?
Zwitterions: these are internal sales and neutral molecules
Draw a zwitterion
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Draw the zwitterionic nature of amino acids in acidic conditions
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Draw the zwitterionic nature of amino acids in alkaline conditions
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What are the properties of amino acids?
High melting points- have strong ionic bonding (IMF) lots of energy to overcome bonding and melt Soluble in water due to ionic properties
Reaction of amino acids with ethanoyl chloride
Has to be done in a fume cupboard as hydrogen chloride produced Dry conditions Produces: CH3CONHCHRCOOH
Structure of an amino acid
NH2CH(R)COOH
How to make an amino acid into a zwitterion
Remove the far end H and put it into the N instead
How does a secondary structure arise from a primary?
From hydrogen bonding between N-H groups in one part and C=O groups in Another part- this is due to parts of the protein folding to form an alpha helix or a beta pleated sheet
Explain importance of proteins in living systems
Cotton fibres contain protein fibres Essential in all living matter eg muscle Enzymes are made up of them- biocatalysts in living cells carry out complex reactions. They’re sensitive to changes in Temp and pH
Why do amino acids have high MPS?
They have strong ionic bonding(IMF) lots of energy needed to overcome bonding and melt them
What happens to the structure of a zwitterion under acidic conditions? Why?
The carboxyl group is removed and replaced with a hydroxy group (OH) Because the zwitterion acts as a base under acidic conditions so accepts H+
What does the zwitterion act as under acidic conditions?
A base- accepts H+