They are coded on our DNA, and are made in a sequence according to that code. Some biopolymers take many more amino acids to "spell out" than others.
When they exit the DNA/RNA "factory" they enter the cell's watery surrounding and TAKE THEIR MOLECULAR SHAPE. The DNA does not directly contain the information about the shape of the molecule, only the sequence of amino acids.
Here is a representation of all 20 amino acids. Don't be worried if you don't know chemistry yet. In what part of their shape do they seem to vary the most? Can you find glycine? It is the smallest.
By the way, we can't make some of our amino acids; we have to get them from breaking down the food we eat.
Let's look inside the amino acid molecules.
