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Biological polymers

are not always man-made - they occur naturally and are made by all living .

DNA

is a polymer which is essential for life. Most DNA is a double helix, where two polymer chains are lined up and then twisted around each other. The DNA polymer is made from four different types of , which are called .

The sequence of nucleotides along the DNA molecule is a code for . The genetic information stored in a molecule for DNA is a set of instructions for each organism to stay alive and grow.

Proteins

are biological polymers made inside cells. They are made from amino acid monomers and have a huge range of roles inside living things. For example, all are made from proteins.

Starch and cellulose

and are biological polymers which are made by plants. The monomers for both starch and cellulose are sugar molecules. Starch is used by plants as a way of storing energy as a complex . Cellulose is used to make the strong cell wall which gives plant cells (and therefore plants) strength.