Answer:
Structure and is found in tendons, bones, and ligaments.
Communication and works as chemical messengers such as hormones.
Defense as in antibodies.
Transportation and are embedded in the cell membrane to allow substances to move across the cell membrane.
Enzymes that lower the activation energy of a reaction.
Contraction to allow muscle and cell contraction/movement.
Explanation:
Proteins serve many functions in living organisms.
Structure: The most abundant protein in mammals is collagen and is found throughout the body. In a major component of connective tissue such as skin, ligaments, and tendons providing strength and elasticity to these tissues. It is found also mineralized in bones and teeth.
Proteins function as hormones which are chemical messengers that mediate many cellular responses in the body. For example, the hormone insulin is a protein.
Proteins functions in the body's immune system as antibodies which recognize and initiate immune responses against diseases. The immunoglobulin such as immunoglobulin A and G are proteins.
Proteins serves as transporters to move substances across the cell memebrane. Some are found as peripheral or integral membrane proteins. Examples of transport proteins are the glucose transporters, Glut-1, Glut-2 and Glut-4 transporters.
Enzymes are proteins which catalyse the chemical reactions tanking place in an organisms. Various enzymes in the body include the hydrolases, the ligands, the leases, etc.
Contraction of the actin filaments of the muscle which are proteins, allow muscle and cell contraction bringing about movement.
A Note on the other options.
Eicosanoids are lipid molecules which serve various functions such as in regulation of blood pressure or inflammation.
Steroids such as cholesterol are lipid-derived molecules.
Glycogen for energy storage in muscles is a storage form of glucose, a carbohydrate.
