Proteins are polymers constructed of 20 different amino acids which in turn are composed of carbon, hydrogen, oxygen, nitrogen and sometimes sulfur and are combined in ways to form the protein molecules an organism needs. ... Proteins also form important bodily structures, they are the important part of the muscles that enables limbs to bend (myosin) and the heart to pump. ... Nucleic acids consist of a pentose sugar bonded to a phosphate group and to one of five different kinds of nitrogenous bases. ... The common steroid structure is the basis of the human sex hormones. ...

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• Grade Level: Undergraduate