Proteins

Protein Basics

• Made of C,H,O, N SPONCH• Monomers = amino acids

- 20 different types of amino acids used to make proteins

• Proteins are the polymer also called a polypeptide

Meet the monomer –Amino acid• 3 main parts - Amino group NH2

- Carboxyl group COOH - R group (side chain) each of the 20 types of amino acids have a unique R group

Proteins form from chains of amino acids

Proteins vary in length – can be 1,000s of amino acids long

Proteins Shape

• A protein’s shape is determined by the order that amino acids are joined in

• The shape of a protein determines its function

Hemoglobin antibody enzymes polymerase

Four Levels of Structure allow for any shape

2-28

Protein Structure

Protein Structure – Primary Structure• Primary structure is the order of the amino acids that

make up a protein. - the interactions of the R groups on each amino acid cause the molecule to bend and fold – different

arrangements create different shapes - as a result- the order of amino acids determines the shape of the protein - shape determines function - changing a single amino acid can change a protein’s shape.

Protein Structure- Secondary Structure• The folding proteins often assume one of two

general shapes – pleated sheets or an alpha helix these are the

protein’s secondary structure. - hydrogen bonds between amino acids

stabilize the secondary structure

Alpha Helix

Protein Structure – Tertiary Structure• The coiled or pleated structures continue to fold until they form a complex three dimensional structure. - most proteins are completed at this stage and are

fully functioning proteins.

Remember: Shape determines function

Protein Shape-Quaternary Structure

• Some more complex proteins are assembled from two

or more protein molecules. - Insulin – 2 forms – 2 proteins or 6 proteins - Hemoglobin – 4 proteins

Protein Functions Proteins are the Worker Molecules of Living Things

Enzymes - proteins that allow chemical reactions to occur in living thingsAntibodies – proteins that protect the body from

infectionStructure – cytoskeleton, hair, nails, muscles, spider

web, silk, feathers ,horns, hooves etc….Hormones – chemical messengersCell membrane – proteins can act as channels through

the cell membrane - receptor proteins found on membrane transmit signals to the inside of cells

• Hemoglobin – protein found in blood that carries oxygen

Proteins can be Denatured• Denatured proteins are proteins that lose their shape - if they lose their shape, they also lose their - What can cause a protein to become denatured? Exposure to: A Strong Acid A Strong Base Heat An organic solvent: Alcohol or Acetone - Denatured proteins can lose quaternary, tertiary and secondary structure - Primary Structure is left untouched

Function…

Denatured Proteins

Vocabulary for the Protein Pro• Polypeptide• R – Group• Peptide Bond• Primary Structure• Secondary Structure• Tertiary Structure• Quaternary Structure• Enzymes• Antibodies

• Cell Membrane Proteins• Hormones• Denatured Protein• 4 things that denature

proteins