What is it? What does it look like?
It makes up the enzymes that power many chemical reactions and the hemoglobin that carries oxygen in your blood. At least 10,000 different proteins make you what you are and keep you that way. Protein is built from building blocks called amino acids. A few amino acids (known as the essential amino acids) must come from food. Animal sources of protein tend to deliver all the amino acids we need.
Its structure looks like many smaller molecules combined to make a much larger molecule hence the name macro molecule.
From: Chan, T. H. "Protein." The Nutrition Source. Harvard, 09 Aug. 2016. Web. 22 Feb. 2017.
What does it do for your body? How is it used?
The Institute of Medicine recommends that adults get a minimum of 0.8 grams of protein for every kilogram of body weight per day (or 8 grams of protein for every 20 pounds of body weight). (1) The Institute of Medicine also sets a wide range for acceptable protein intake—anywhere from 10 to 35 percent of calories each day. Hair and nails are mostly made of protein. Your body uses protein to build and repair tissues. You also use protein to make enzymes, hormones, and other body chemicals. Protein is an important building block of bones, muscles, cartilage, skin, and blood.
From: Annigan, Jan. "Protein Digestion Inside the Human Body." Healthy Eating | SF Gate. SF Gate, n.d. Web. 22 Feb. 2017. <http://healthyeating.sfgate.com/protein-digestion-inside-human-body-6044.html>.
Where does it come from? Internally and externally.
Your body regulates protein digestion through hormones and nerve signals. Gastrin stimulates your stomach cells to produce acid, while secretin tells your pancreas to secrete both bicarbonate and digestive enzymes. Cholecystokinin is a third hormone involved in protein digestion, which also directs your pancreas to release digestive enzymes. Your nervous system assists in protein digestion by responding to the physical presence of food in your digestive tract. Stimulation of nerves in this area helps move food through the different organs of your gut. All foods made from meat, poultry, seafood, beans and peas, eggs, processed soy products, nuts, and seeds are considered part of the Protein Foods Group. Beans and peas are also part of the Vegetable Group. In general, 1 ounce of meat, poultry or fish, ¼ cup cooked beans, 1 egg, 1 tablespoon of peanut butter, or ½ ounce of nuts or seeds can be considered as 1 ounce-equivalent from the Protein Foods Group.
From: "All about the Protein Foods Group." Choose MyPlate. USDA, 29 July 2016. Web. 22 Feb. 2017. <https://www.choosemyplate.gov/protein-foods>. Goldhamer, D.C. Alan. "Where Do You Get Your Protein?" Center for Nutrition Studies. Center for Nutrition Studies, 02 Mar. 2016. Web. 22 Feb. 2017. <http://nutritionstudies.org/get-protein-where/>.