Get started on the subjects that Professor Ahern calls "the science of us": biochemistry and its allied field molecular biology, which both tell us who we are. Discover the handful of elements involved in biochemical reactions; the bonds they form; and the wide array of molecules that result, including amino acids, which are the building blocks of proteins. #Science & Mathematics

Investigate why water is so singularly suited to life. Composed of two hydrogen atoms for each oxygen atom, water molecules have a polar charge due to the uneven arrangement of shared electrons. See how this simple feature allows water to dissolve sugars and salts, while leaving oils and fats untouched. Also learn what makes water solutions acidic or basic.

Take a tour through the 20 amino acids that link together in different combinations and sequences to build proteins. Besides water, proteins are the most abundant molecules in all known forms of life. Also the most diverse class of biological molecules, proteins make up everything from enzymes and hormones to antibodies and muscle cells.

Learn how peptide bonds join amino acids to form an almost unlimited number of protein types. The order of amino acids matters, but even more important are the shapes they form. Survey primary, secondary, tertiary, and quaternary protein structures, with examples from silk (a fibrous protein with mostly secondary structure) to the intricately folded hemoglobin protein (a quaternary structure).

Discover how proteins fold into complex shapes, often with the help of molecular chaperones. Then learn the deadly consequences of proteins that do not fold properly, leading to degenerative conditions such as Alzheimer's, Parkinson's, and prion diseases. Also look at intrinsically disordered proteins, which lack a fixed structure, permitting flexible interactions with other biomolecules.

Hemoglobin is the protein in red blood cells that carries oxygen from lungs to tissues and then takes away carbon dioxide for exhalation. Learn how structure is the key to this complicated and vital function. Also see how variant forms of hemoglobin, such as fetal hemoglobin and the mutation behind sickle cell anemia, can have life-saving or fatal consequences - all depending on structure.