11.03.4 Amino Acids (HT)

Syllabus

Amino acids have two different functional groups in a molecule.
Amino acids react by condensation polymerisation to produce polypeptides.
For example: Glycine is H₂NCH₂COOH and polymerises to produce the polypeptide (-HNCH₂COO-)_nand n H₂O
Different amino acids can be combined in the same chain to produce proteins.

You may have heard of Amino Acids in Biology.

But you won't have been listening then.

Amino Acids are important because they make up the proteins we need to live

An Amino Acid has two functional groups (reactive parts of the molecule).

The Amino group is -NH₂ (Amino means like Ammonia, which is NH₃)

The acid refers to a Carboxylic Acid group (COOH).

The simplest Amino acid is Glycine.

The structure is shown on the right

Since the syllabus mentions Glycine by name it suggests that you should learn this.

If we had two amino acid molecules they can link together a bit like the way esters form.

This links the two molecules and also eliminates a bit of water.

The join between the two molecules is the peptide link.

You won't be asked to draw this, but you may be expected to learn the name and to be able to label it

If we had many amino acid molecules then more peptide links could form at the ends.

The chain could get longer and longer - we would have another type of condensation polymer - a polypeptide.

Proteins are natural polypeptides made up of many different amino acids in complicated arrangements that we don not need to know about.

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