3.  Contain carbon, hydrogen, oxygen, nitrogen, and sulfur  Serve as structural components of animals  Serve as control molecules (enzymes)  Serve as transport and messenger molecules  Basic building block (monomer) is the amino acid

4. Amino group acts like a base, tends to be positive. Carboxyl group acts like an acid, tends to be negative. “R” group is variable, from 1 atom to 20. Two amino acids join together to form a dipeptide. Adjacent carboxyl and amino groups bond together.

8.  Two AAs combine to form a dipeptide. ◦ Joined by covalent peptide bond!  Many AAs can join together to form polypeptides, which can have hundreds of AAs linked together  Proteins are made of polypeptides. ◦ Shape can change due to temp and solution.

9. Formation of a Dipeptide Dehydration synthesis!!

10. Amino Acid + Amino Acid --> Dipeptide Amino Acid + Dipeptide --> Tripeptide A.A. + A.A. + …..+ Tripeptide --> Polypeptide

11.  Proteins can be made of one or more polypeptides!

12.  Involved in nearly all metabolic processes  Enzymes are specific proteins that speed up chemical reactions (catalysts!) ◦ If there were no enzymes, reactions would not take place under living conditions  Enzymes have active sites for molecules to bind to and form a product  Substrates are reactants to be catalyzed.