1.Basic Structural Unit of Animal
a.Collagen - mostly found in fibrous tissues suchas tendon, ligament and skin, and is alsoabundant in cornea, cartilage, bone, bloodvessels, the gut, and intervertebral disc.
c.Blood proteins – hemoglobin is polypeptides (protein)
d.Keratin proteins – skin, hair, feathers
e.Contractile proteins - muscle