Introduction to Proteins

The 4 major macromolecules of living cells:

ProteinsLipidsCarbohydratesNucleic 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 cellGreat diversity in biological function

“They are the molecular instruments through which genetic information is expressed.”

Protein: The StructureAmino 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

(NH3)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 AcidsDifferent combinations

of amino acids make up products such as:HormonesenzymesSpider web AntibodiesLens protein of the eye

FeathersRhino HornMilkAntibioticsMushroom poisonAND MUCH MORE!

Amino Group (NH3+)

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 (NH3

+ ) bonded to the same carbon atom (the alpha carbon)

Amino Acids have common structural features

They differ by their R-groups, which vary in:SizeStructureCharge (+/-)polarity