SBI 3C1

 The largest percentage of body tissue is made up of protein.  Proteins are NOT primarily used for energy like carbohydrates and fats, but rather are associated with cell structure and function.

Proteins can be found in different forms: 1. Building material – muscles, organs, skin, nails, hair (keratin) 2. Silk – forms spider webs 3. Hemoglobin – used to carry O 2 in red blood cells 4. Enzymes – help speed up chemical reactions 5. Hormones - eg. insulin – helps transport sugar from blood into cells 6. Collagen – support to bones and tendons 7. Membrane Proteins – transport material across the cell membrane

 Proteins (polymers) are composed of amino acids (momoners).  There are 20 different amino acids  Amino acids have a central carbon atom with an amino group, a carboxyl group, and an R group attached to it.

 8 amino acids cannot be made by the human body (ESSENTIAL AMINO ACIDS)  They must be obtained in the food you eat.  Can be obtained from meat.  Vegetarians obtain their essential amino acids through legumes (tofu, beans, lentils).

Amino terminus (end) Carboxyl terminus (end) Peptide Bond bond between amino acids

 Dipeptide = 2 amino acids linked together  Polypeptide = a short chain of amino acids  Proteins (polymers) = long, unbranched chains of amino acids (monomers of proteins/polypeptides)  Most functional proteins contain hundreds or thousands of amino acids

Meat Cheese Fish Eggs Milk Legumes:

 Occurs when proteins lose their structure/unfold from their 3-D shape.  Can cause the protein to stop working properly.  Caused by high temperatures, extremely acidic/basic environments, high salt concentrations, etc.

 Heat denatures hair proteins and allows you to straighten & curl your hair.  Fevers above 39  C can denature critical enzymes in the brain, leading to seizures and possibly death.  High concentrations of salts or pickling foods (eg. vegetables) with vinegar preserves food by denaturing enzymes in bacteria that would cause food to spoil.