3S: Proteins

Shireen Rudina

What do proteins do?

• Structure– Collagen in skin, keratin in hair and nails

• Signaling between cells

• Defend against disease– Antibodies

• Facilitate Reactions (enzymes)

• Do essential work in each cell

Which of these are proteins:

1. DNA2. Fibers in your heart muscle3. ?4. ?

Catalase is an enzyme

2H2O2 2H2O + O2 + heat

Does not happen spontaneously, only in the presence of catalase.

Important: Keeping your data organized!

Bubbles Heat Splint Test

Control

Liver

Liver, high pH

Liver, low pH

Heated Liver

Peptide Bonds Connect Amino Acids

Proteins are made of monomers called amino acids

Polypeptide

• Many amino acids connected by peptide bonds polypeptides

20 amino acids

Structural Activity

Primary Structure

• Order of amino acids linked together in a long chain

• One end carboxyl & one end amino

Secondary Structure

• Chain of a.a.s bends based on the R groups

Alpha helix or Beta pleated sheets

Tertiary Structure

• Further folding of the polypeptide chain– Disulfide bridges

Quaternary Structure

• Different polypeptide chains come together to form the final protein