Collagen and elastin provide a fibrous framework in animal connective tissues. Keratin is the protein of hair, horns, feathers, and other skin appendages. Support 1. Structural Examples Function Type of protein
Casein, the protein of milk, is the major source of amino acids for baby mammals. Plants have storage proteins in their seeds. Storage of amino acids 2. Storage
Hemoglobin, the iron-containing protein of vertebrate blood, transports oxygen from the lungs to other parts of the body. Other proteins transport molecules across cell membranes. Transport of other substances 3. Transport
Insulin, a hormone secreted by the pancreas, helps regulate the concentration of sugar in the blood of vertebrates. Coordination of an organism’s activities 4. Hormonal
Receptors built into the membrane of a nerve cell detect chemical signals released by other nerve cells. Response of cell to chemical stimuli 5. Receptor
Actin and myosin are responsible for the movement of muscles. Movement 6. Contractile
Antibodies combat bacteria and viruses. Protection against disease 7. Defensive
Digestive enzymes catalyze the hydrolysis of the polymers in food. Selective acceleration of chemical reactions 8. Enzymatic
Proteins are made of subunits of amino acids .
8 of these amino acids are essential – they must be
eaten in your diet (your body can’t synthesize them).
Proteins are the most diverse class of macromolecules due to 20 available amino acids.
Amino Acids BASIC ACIDIC * * * * * * * * *
1. amino group
2. carboxylic acid (carboxyl) group
3. hydrogen atom
4. variable R group (or side chain)
Amphiprotic: containing both acidic (COO - ) and
basic (NH 3 + ) functional groups
In aqueous solution: carboxyl group donates H + ion to
Amino acid structure H | H 2 N – C – COOH | R H | + H 3 N – C – COO - | R +H 2 O
Peptides amide bond
Four layers of protein organization:
primary (1°) structure
secondary (2°) structure
tertiary (3°) structure
quaternary (4°) structure
Primary (1 ° ) Structure
sequence of amino acids
Example: Sickle Cell Anemia
abnormal hemoglobin develop because of a single amino acid substitution (change)
causes hemoglobin to crystallize, deforming the red blood cells and leading to clogs in blood vessels.