5.4 Protiens perform most functions in cells

• a protein is a polymer constructed from a set of just 20 kinds of monomers called amino acids


• an amino acid monomer consists of a central carbon atom bonded to four partners


• by linking amino acids together into a chain called polypeptide


• a protein in the simple form of amino acids linked together cannot function properly


• an unfavorable change in temperature, pH, or some other quality of environment can cause a protein to unravel and lose its normal shape which is a process called denaturation of the protein

Concept check

1. Give at least two examples of proteins you can "see" in the world around you. What are their functions?

1. hair and fur; its function is provide warmth and protection

2. muscle tissue; its function is to allow us to move

2. Relate amino acids, polypeptides, and proteins.

Amino acids are monomers that consist of a central carbon atom; polypeptides are made of linked amino acids; and a protein, like a polypeptide, is made of 20 amino acids.

3. Explain how heat can destroy a protein.

Heat can destroy a protein because hot molecules collide with enough power to break the weak attraction.

4. Which parts of an amino acid's structure are the same in all amino acids? Which part is unique?

The central base of an amino acid's structure which contains the 4 partners - carbon atom, hydrogen, and two others - are always the same in an amino acid. The side group that attaches to the 4 bond is the unique part of an amino acid's structure.