Proteins include a diversity of structures, resulting in a wide range of functions

Proteins

Molecule consisting of polypeptides (polymers of amino acids) folded into a 3D shape

- Comprised of C, H, O, N, and S
- Shape determine function

Monomer: Amino Acids

Molecules that have an amino
group and a carboxyl group

- 20 different amino acids

Amino Acids

○ Unique aspects of the AA are based on the side

chain’s physical and chemical properties

○ Side chains can be grouped as:

■ Nonpolar
■ Polar
■ charged/ionic

Amino Acids

Side chains interact, which determine the shape and function of the protein

Formation of Peptide Bonds

A carboxyl group of one AA must be positioned next to the amino group of another AA

Polypeptides

Many AA linked by peptide bonds

Each polypeptide has a unique sequence of AAs and directionality

- One end is a free amino group called the N-terminus
- One end is a free carboxyl group called the C-terminus

Functions of Proteins

○ Antibody-help protect the body from disease
○ Enzyme- carry out chemical reactions or assist in creating new molecules

○ Messenger- transmit signals (ie hormones)
○ Structural- provide structure and support
○ Transport/storage- bind to and carry small atoms and

molecules through the body

​Primary Structure

Linear chain of AA

• Determined via genes

• Dictates secondary and tertiary forms

Secondary

Coils and folds due to hydrogen bonding within the polypeptide chain

Tertiary

3D folding due to interactions between the side chains of AAs

-Reinforced by hydrophobic interactions and disulfide bridges of the side chains

​R-Groups and their characteristics

Quaternary

Association of 2 or more polypeptides

- Found in only some proteins