9/25/21, 12:14 AMCH02 Lecture Notes: BIO-168-OA01-ML FL21 Human Anatomy and Physiology I w/ lab (P) (4 cr) - Bridget Boyle1/4CH02 Lecture NotesThe Chemical Level of OrganizationChemistry is the foundation of all living organisms. All basic physiological processes of life take placeat the chemical level.I. Atoms, Molecules and Bonds1. (*) The physical world (matter) is made up ofatoms, which join together to form chemicals withdifferent characteristics. These chemical characteristics determine the physiology of livingorganisms at the molecular and cellular level.2.Atoms are the smallest units of matter with their own chemical characteristics.3. Atoms are divided into 2 basic regions:1. the centralnucleus, contains heavy particles2. theelectron cloud, contains very light, moving particles4. Atoms have 3 major types of smaller orsubatomic particles. Particles are defined byelectricalcharge (positive or negative), weight ormass, and location within the atom.1.protons (p+):positive charge, about 1 unit of mass, in the central nucleus2.neutrons (n): no electrical charge (neutral), about 1 unit of mass, in the central nucleus3.electrons (e-):negative charge, very small mass, spin rapidly in a cloud around the centralnucleusChemical Bonds1. There are 3 basic types of chemical bonds:ionic,covalent andhydrogen.1.Ionic bonds form between atoms with opposite electrical charges (ions).1. An atom that loses electrons (electron donor) has a netpositivecharge, and is called acation.2. An atom that gains electrons (electron acceptor) has a netnegativecharge, and is ananion.2.Covalent bonds occur when atoms share, rather than gain or lose electrons, formingmolecules.3.Hydrogen bonds are weak attractions between the positive, hydrogen side of one polarmolecule and the negative side of another polar molecule. Hydrogen bonds influence theshape of larger molecules, which is important to molecules such as proteins and DNA.