Introduction to Proteins

The 4 major macromolecules of living cells:  Proteins  Lipids  Carbohydrates  Nucleic Acids

Proteins are the most abundant macromolecule in living cells.  In all cells and all parts of cells  Occur in a great variety  Thousands of different proteins can be found in 1 cell  Great diversity in biological function “They are the molecular instruments through which genetic information is expressed.”

Protein:The Structure  Amino Acids are the monomeric subunit of a protein.  Monomer= “single unit”  Proteins are chains of subunits (monomers) called amino acids

Protein:The Structure  All proteins, whether from prehistoric bacteria, or today’s complex life forms, are composed from the same ubiquitous set of 20 amino acids, covalently linked in different sequences

AMINO ACIDS  Made up of an Amino group (NH 3 ) and a carboxyl group (COOH)  20 different amino acids exist  Amino acids differ by their “R” group, or side chain  Same 20 amino acids are joined in different combinations to determine the function and shape of the 1000s of proteins that exist

Amino Acids  Different combinations of amino acids make up products such as:  Hormones  enzymes  Spider web  Antibodies  Lens protein of the eye  Feathers  Rhino Horn  Milk  Antibiotics  Mushroom poison  AND MUCH MORE!

Amino Group (NH 3 + )

Carboxyl group puts the “Acid” in Amino Acid

Amino Acids have common structural features  All 20 amino acids found in proteins have a carboxyl group (COOH or COO- ) and an Amino group (NH 3 + ) bonded to the same carbon atom (the alpha carbon)

Amino Acids have common structural features They differ by their R-groups, which vary in:  Size  Structure  Charge (+/-)  polarity