What do all proteins have in common? (what are they made of? )

Explanation:

Collagen is a protein that all animals have common. Collagen is a most abundant protein in the body , found in the bones, muscles, skin, and tendons. It is the substance that holds the body together.Collagen is used in medical purpose, including the repair of body tissues. It is a kind of substance which are hold together.  Collagen is a cable-like protein that can calcify into bone, shell or other hard structures .Collagen  is the main structural protein in the extracellular space in the various connective tissues in the body. It is mostly found in fibrous tissue such as ligaments ,tendon, skin.

well we can't tell you because we cant see the time give a screen shot or something.

he is very short, and he can only reach halfway up on the elevator buttons. but on a rainy day, he has his umbrella with him, and he uses it to poke the button at the top.