Proteins Unit
Intro to Proteins
Amino acids by definition are one carbon atom connected to an amino group (NH2), a carboxyl group (COOH), a hydrogen atom, and a functional side chain (denoted in chemical schematics as R) that determines the nature of the amino acid. In a peptide bond, the amino group of one amino acid is bonded to the carboxyl group of another amino acid by the loss of a hydrogen atom from the amino group and the loss of an OH group from the carboxyl group, which are then combined to form one water molecule: (in this schematic, A is the rest of the amino acid) A-NH2 + COOH-A ––> A-NH-COO-A + H2O. Since each amino acid has an amino group and carboxyl group, an amino acid can have peptide bonds between up to two other amino acids, allowing amino acids to form long strings, or polypeptides, and different types of amino acids can bond together in unique sequences and combinations. A protein is a polypeptide comprised of at least 100 amino acids. When a protein becomes long, amino acids in one section can start to bond with amino acids in a different section of the protein through hydrogen bonds or disulfide bonds, resulting in a warping of the protein's fibrous shape into a big glob. The nature and sequence of each amino acid in a protein, as well as the protein's precise shape, determines the protein's function.
Life cannot exist without amino acids, and by extension proteins, to perform the various tasks necessary for the upkeep of cells, tissues, and the processes necessary to sustain life. Thus, proteins are found in every food that was made from a plant or animal, or a product thereof. However, not all proteins are created equal. There are 20 different amino acids, and the human body needs all of them to survive. It can manufacture 12 of them (infants can manufacture 11). The remaining amino acids are called essential amino acids, and must be eaten. A complete protein has substantial amounts of every essential amino acid; the proteins found in meat are typically complete proteins. Vegetable, grain, and legume proteins, on the other hand, are typically incomplete proteins, meaning that they do not contain every essential amino acid. However, different vegetables, grains, and legumes will have proteins with different amino acids, and someone on a vegetarian or vegan diet can gain every essential amino acid simply by eating a variety of foods.
Proteins, or the amino acids in the proteins we make and eat, are used in the body for almost everything. They complete essential functions in the human cells, they transport oxygen in the bloodstream, they fight infections and diseases, they break down foods, they catalyze chemical reactions (particularly in the digestive system), and they even serve as the building blocks for various tissues.
Life cannot exist without amino acids, and by extension proteins, to perform the various tasks necessary for the upkeep of cells, tissues, and the processes necessary to sustain life. Thus, proteins are found in every food that was made from a plant or animal, or a product thereof. However, not all proteins are created equal. There are 20 different amino acids, and the human body needs all of them to survive. It can manufacture 12 of them (infants can manufacture 11). The remaining amino acids are called essential amino acids, and must be eaten. A complete protein has substantial amounts of every essential amino acid; the proteins found in meat are typically complete proteins. Vegetable, grain, and legume proteins, on the other hand, are typically incomplete proteins, meaning that they do not contain every essential amino acid. However, different vegetables, grains, and legumes will have proteins with different amino acids, and someone on a vegetarian or vegan diet can gain every essential amino acid simply by eating a variety of foods.
Proteins, or the amino acids in the proteins we make and eat, are used in the body for almost everything. They complete essential functions in the human cells, they transport oxygen in the bloodstream, they fight infections and diseases, they break down foods, they catalyze chemical reactions (particularly in the digestive system), and they even serve as the building blocks for various tissues.
Protein Structural Models (to the Right)
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Protein Reflection
Before this unit, I knew vaguely that protein was found in meat and that it was a necessary part of the human diet. I had not heard of amino acids, and I did not know that they served so many functions in the human body. I knew what enzymes are, what antibodies and white blood cells are, and what hemoglobin is, but I did not know that they were all amino acids or proteins. I had also never heard of essential amino acids, but I now know that there are certain amino acids that I need to eat to survive, and that complete proteins containing all of these amino acids are best found in meat and animal products. I've never disliked eating meat, but now it somehow seems even more appealing to me, since I now know the chemistry behind the necessity for eating meat.