MACROMOLECULES: PROTEINS

SBI 3C1

FUNCTIONS OF PROTEINS:

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.

FUNCTIONS OF PROTEINS

Proteins can be found in different forms:

1. Building material – muscles, organs, skin, nails, hair (keratin)

2. Silk – forms spider webs3. Hemoglobin – used to carry O2 in red blood cells

4. Enzymes – help speed up chemical reactions5. Hormones - eg. insulin – helps transport sugar from

blood into cells6. Collagen – support to bones and tendons7. Membrane Proteins – transport material across the cell

membrane

COMPOSITION OF PROTEINS 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.

20 AMINO ACIDS:

ESSENTIAL AMINO ACIDS 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).

FORMATION OF POLYPEPTIDES & PROTEINS

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

4 LEVELS OF

PROTEIN STRUCTURE

FOODS THAT CONTAIN PROTEINS:

MeatCheeseFishEggsMilk

Legumes:

DENATURATION 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.

EXAMPLES OF DENATURATION: Heat denatures hair proteins and allows

you to straighten & curl your hair.

Fevers above 39C 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.