Summary
Highlights
Proteins are composed of hundreds or thousands of amino acids linked together in long chains. Their structure is determined by DNA through genes, and there are 20 different types of amino acids. The specific order of these amino acids dictates each protein's unique shape and function.
Hormones are examples of messenger proteins, secreted by endocrine glands. They act as chemical messengers, transmitting signals between cells. Examples include insulin, which regulates blood sugar levels, and adrenaline, which increases blood circulation and breathing in stressful situations as part of the fight-or-flight response.
Enzymatic proteins accelerate chemical reactions in the body, such as liver functions and stomach digestion. Digestive enzymes, for instance, break down food into simpler forms for easy absorption.
Structural proteins are vital components of the body, including collagen, keratin, and elastin. Collagen forms the connective framework for muscles, bones, and cartilage, while keratin is the main structural component of hair, nails, and skin.
Defensive proteins, like antibodies, are large Y-shaped proteins used by the immune system to identify and attack harmful bacteria and viruses. They are formed in white blood cells and recognize specific antigens on pathogens to initiate an attack.
Transport proteins carry vital materials to cells, while storage proteins help store them. Hemoglobin, for example, transports oxygen from the lungs to body tissues. Other proteins like cowbinding aid in calcium absorption and storage, and ferritin stores and releases iron in a controlled manner.