 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
• 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.

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.
Formation of a Dipeptide
Dehydration synthesis!!
Amino Acid + Amino Acid --> Dipeptide
Amino Acid + Dipeptide --> Tripeptide
A.A. + A.A. + …..+ Tripeptide --> Polypeptide

Proteins can be made of one or more polypeptides!

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.