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Slide 1

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· Made of a carboxyl (acid ­ COOH) group, an
amine (alkali ­ H2N) group and a variable R
· Joined together by peptide bonds to form a
dipeptide and a water molecule, then a
polypeptide chain
· Glycine is the smallest amino acid with just a
hydrogen as its R-group…read more

Slide 2

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· PRIMARY: The sequence of amino acids in the
polypeptide chain
· SECONDARY: Self-assembles into alpha helices
or beta pleated sheets. They are held in place
by hydrogen bonds between the amino acids.
Alpha helices contain amino acids with smaller
R-groups as it is a tight coil of 3.6 amino acids
per turn.…read more

Slide 3

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· TERTIARY: The 3D structure of the protein held in
place by these interactions:
· Hydrogen bonds between the R-groups
· Ionic bonds between +ve and ­ve R-groups
· Disulphide bonds between two cysteine R-groups
· Hydrophobic and hydrophilic interactions.
Hydrophobic R-groups always end up on the inside
· QUATERNARY: The interaction between several
polypeptide chains and a prosthetic group
· Eg: Haemoglobin has 4 chains and a haem (iron)
group…read more

Slide 4

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· COLLAGEN: Fibrous protein, forms
supportive tissues in animals, needs to be
· Three polypeptide chains that are tightly
coiled into a triple helix
· Joined together by strong covalent bonds
· HAEMOGLOBIN: Globular transport protein
· The hydrophilic side chains are on the outside
and the hydrophobic side chains are on the
inside making it soluble, essential for
transporting things in the blood…read more


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