What are proteins and what do they do? Proteins are large, complex molecules that play many critical roles in the body. They do most of the work in cells and are required for the structure, function, and regulation of the body’s tissues and organs. Proteins are made up of hundreds or thousands of smaller units called amino acids, which are attached to one another in long chains. There are 20 different types of amino acids that can be combined to make a protein. The sequence of amino acids determines each protein’s unique 3-dimensional structure and its specific function. Amino acids are coded by combinations of three DNA building blocks (nucleotides), determined by the sequence of genes. Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. Proteins differ from one another in their sequence of amino acids. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20-30 residues, are commonly called peptides, or oligopeptides. The individual amino acid residues are bonded together by peptide bonds. The sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the genetic code specifies 20 standard amino acids. Many proteins are enzymes that catalyze biochemical reactions. Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton. Other proteins are important in cell signaling, immune responses, cell adhesion, and the cell cycle.
The correct answer and explanation is :
Proteins are large, complex molecules made up of chains of smaller units called amino acids. These molecules play vital roles in the body, involved in nearly every function within cells. There are 20 different amino acids that can be combined in various sequences to form unique proteins. The sequence of amino acids in a protein determines its specific 3D structure and function.
Proteins are essential for a wide range of biological functions. One of the primary functions of proteins is to act as enzymes, which are catalysts that speed up biochemical reactions in cells. Without enzymes, many vital chemical reactions in the body would occur too slowly to sustain life. For example, digestive enzymes break down food molecules, allowing the body to absorb nutrients.
Proteins also provide structural support. For example, actin and myosin are proteins found in muscle tissue that work together to facilitate muscle contraction. The cytoskeleton, a network of proteins within cells, gives the cell its shape and helps with cell division and movement.
Moreover, proteins are involved in cell signaling, which is essential for communication between cells. This signaling helps coordinate processes such as growth, immune responses, and tissue repair. For example, certain proteins act as receptors on the surface of cells, allowing them to receive and respond to signals from other cells.
In addition, proteins are crucial in the immune system. Antibodies, which are proteins, bind to and neutralize foreign invaders like bacteria and viruses, helping protect the body from infections. Other proteins are involved in cell adhesion, helping cells stick together to form tissues and organs.
Proteins are made according to the genetic instructions encoded in DNA. The sequence of amino acids in a protein is determined by the sequence of nucleotides in a gene, and this genetic code guides the synthesis of proteins during a process called translation. Proteins are fundamental to life, as they are involved in maintaining the structure, function, and regulation of the body’s tissues and organs.