Answer:
Proteins serve many functions within an organism, such as mammals. Proteins are used to grow and repair tissues. ... Proteins also form hormones, which transport chemical messages between tissues and organs. Proteins are also important building blocks of bone, carilage, muscle, skin, and blood.
Link:
https://www.enotes.com/homework-help/outline-role-proteins-life-mammals-547196
What exactly are you trying to ask ??
The answer is carbon, hoped this helps you!