Macromolecules – Day 1 PROTEINS

BACKGROUND “molecule of action” Cause most things in your body to happen – to do work Sources of protein: Location of protein within your body: muscles, hair, fingernails, in cells as enzymes

EWW!

STRUCTURE OF PROTEIN All proteins have the same basic structure: They are unbranched polymers of amino acids (a.a.) Polymer: long chain of connected units – each unit is a monomer In proteins specifically, the “chain” is a polypeptide and each “link” is an amino acid The linkage that forms between a.a. units is called a peptide bond

Amino Acids (a.a.) There are 20 different a.a. 8 of the 20 a.a. are essential a.a. which the human body cannot produce so these a.a. must be obtained from food All a.a. have the same basic structure: They are small molecules with a central carbon atom attached to: An amino group A carboxyl group A hydrogen atom *A side chain (R)* - the structure of the R makes each a.a. different

Diagram of Amino Acid Structure

Structure of Protein Con’t Proteins can have one hundred to thousands of a.a. in their chain a.a.’s may appear in a protein many times The order of the a.a.’s determines the shape of the protein The shape of the protein determines its job

Diagram of a Protein (polypeptide): CYSTEINE LEUCINE SERINE LYSINE Peptide Bond Amino Acid (monomer)

ENZYMES Type of protein that speeds up chemical reactions Needed to speed up almost every reaction that occurs in living organisms Reusable The active site is the location where the chemical reactions take place E.g. salivary amylase – breaks down sugars in your mouth

HORMONES Type of protein that acts as a chemical messenger E.g. insulin – regulates blood sugar levels E.g. Human growth hormone (HGH)

DENATURATION OF PROTEINS Changing the shape of the protein caused by changes in the environment may/does stop the protein from doing its job Protein’s functions usually return when environmental factor is removed, as long as the peptide bonds between a.a. have not been broken

Denaturation Con’t Denaturation of proteins (including enzymes) can be caused by exposure to: Extremely high temperatures (above 40oC) Acids/bases (pH) Salty environments High sugar

Application of Denaturing Proteins Fever above 39oC is dangerous since it may denature critical brain enzymes, leading to seizures and possibly death Straightening/curling hair with treatments denatures proteins in hair causing hair to straighten or curl

Application of Denaturing Con’t Curing meats or vegetables in vinegar – preserves food by denaturing enzymes in bacteria that cause food to spoil Fruit and vegetables turn brown when exposed to air due to enzyme reactions: blanching fruit and veg (dipping quickly in boiling water) denatures enzymes that cause them to turn brown (or could squeeze lemon juice = acidic)