An Amino Acid has a structure and shape that obeys well defined laws of chemical bonding causing it to layout precisely in according to specific angles and distances between the various atoms.
Some of the bonds act like a hinge allowing the molecule to swivel on a "ball bearing."
When these molecules chain together,these hinges allow the entire chain to fold up into super structures that take on quite complex forms which allow the structure to perform certain functions in accordance with its form.
Some of the proteins become transport vehicles, others become robotic machines, while still others become "keys" that can unlock other structures. The combination of various super structures of proteins eventually becomes the various tissues such as hair, muscle, skin, etc. uniquely performing their designed function.
It all starts with the geometry and arrangement of the amino acids in a specific sequence which allows the proteins to fold into particular shapes.