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Structure- collagen, keratin

Enzymes- amylase, catalase

Transport- haemoglobin

Pumps- Na+K+ pump in cell membranes

Motors- myosin

Hormones- insulin, glucagon

Receptors- rhodopsin

Antibodies- immunoglobulins

Storage- albumins, casein in milk

Blood clotting- thrombin, fibrin

Toxins- diphtheria toxin

Antifreeze- glycoproteins in the arctic flea

And many more!

Proteins

Proteins are made of amino acids. Amino

acids are made of the four key elements

C.................. H.....................

O.................... N....................., some also

contain Sulphur.

The General Structure of an

Amino Acid

Simplified Amino Acid

The general structure of amino acids

All amino acids have the same general structure: the only difference

between each one is the nature of the R group.

amino

group

carboxyl

group

R group

There are 20 different R groups, and so 20 different amino acids.

Since each R group is slightly different, each amino acid has

different properties, and this in turn means that proteins can have a

wide range of properties.

What is the ‘R’ group?

What is the ‘R’ group?

This is the variable group that makes

each amino acid different in its

structure and properties

Amino Acids

are joined

together by

Peptide Bonds

The reaction

involves the

formation of a

molecule of

water in

another

Condensation

reaction

A PEPTIDE BOND

O H

• C - N -

One Amino Acid Another Amino Acid

Formed by Condensation

Broken by Hydrolysis

When polypeptides fold, they form PROTEINS