Proteins are polymers made of amino acid monomers linked by peptide bonds. They perform essential structural and functional roles in the human body such as giving structure, regulating processes, providing protection, and catalyzing chemical reactions as enzymes. Proteins are made of combinations of 20 different amino acids that contain carbon, hydrogen, oxygen, and nitrogen and consist of polypeptide chains formed from joining amino acids through dehydration synthesis reactions. They have a variety of important physiological roles including acting as enzymes, antibodies, transporters, and components of the cytoskeleton.

1. Objec&ve 2.12: Proteins
• Iden&fy the monomers and polymers.
• Compare and contrast general molecular structure.
• Provide specific examples.
• Iden&fy dietary sources.
• Discuss physiological and structural roles in the human body.

2. Proteins
• Proteins give structure to the body, regulate
processes, provide protec&on, help muscles to
contract, transport substances, and serve as
enzymes.
• Contain carbon, hydrogen, oxygen, and
nitrogen

3. Proteins
• Constructed from combina&ons of 20 amino
acids.
– dipep&des formed from 2 amino acids
joined by a covalent bond called a pep&de
bond
– polypep&des chains formed from 10 to 2000
amino acids.
• Pep&de = 10 – 100 amino acids (aa)
• Protein = 100+ amino acids

4. 4 Components of an Amino Acid
• Central carbon atom
• Amino group (NH2)
• Carboxyl group (COOH)
• Side chains (R groups) vary
between amino acids
• 4 classes of side chains:
– Nonpolar
– Polar
– Acidic
– Basic

6. Forma&on of a Dipep&de Bond
• Dipep&des formed from 2 amino acids joined by a covalent
bond called a pep&de bond
– dehydra&on synthesis
• Polypep&des chains contain 10 to 2000 amino acids.

7. A Few Roles of Proteins
• Enzymes: catalyze chemical reac&ons
• An&bodies: immune response
• Transporters: move material into and out of a
cell, through the body
• Channels: move material into and out of a cell
• Cytoskeleton: support the cell
• Hormones & Receptors: signaling and
regula&on, maintain homeostasis