Here's why:

* Building Tissues: Proteins are the major structural components of cells and tissues. They form the framework for bones, muscles, skin, and connective tissues.

* Life Functions: Proteins are involved in almost every essential life process:

* Enzymes: Catalyze (speed up) chemical reactions in the body.

* Hormones: Act as chemical messengers to regulate various processes.

* Antibodies: Protect the body from foreign invaders.

* Transport: Carry molecules like oxygen (hemoglobin) and nutrients throughout the body.

* Contraction: Essential for muscle movement.

In summary: Proteins are the workhorses of the body, responsible for building and maintaining tissues, and carrying out the many functions necessary for life.