Chapter 2 - The Chemistry of Life exam study guide questions and answers

Atom The basic unit of matter. Nucleus The center of the atom that is formed by protons and neutrons bound together with strong forces. Electron A negatively charged particle ( - ) with only 1/1840 mass of a proton that surrounds the nucleus. How are all of the isotopes of an element similar? Because they have the same number of electrons, all isotopes of an element have the same chemical properties. Element A pure substance that consists entirely of one type of atom. Isotope Atoms of the same element that differ in the number of neutrons they contain. In what ways do compounds differ from their component elements? The physical and chemical properties of a compound are usually very different from those of the elements from which it is formed. Compound A substance formed by the chemical combination of two or more elements in definite proportions. What are the main types of chemical bonds? The main types of chemical bonds are ionic bonds and covalent bonds. Ionic Bond Formed when one or more electrons are transferred from one atom to another. Ions Positively and negatively charged atoms because of transferred electrons. Covalent Bond Formed when moving electrons actually travel about the nuclei of both atoms and share them between atoms. Molecule The smallest unit of most compounds. van der Waals forces When molecules are close together, a slight attraction can develop between the oppositely charged regions of nearby molecules. It's named after the scientist who discovered them. How does the structure of water contribute to its unique properties? Because water is a polar molecule, it is able to form multiple hydrogen bonds, which account for many of water's special properties. Hydrogen Bond The attraction between a hydrogen atom on one water molecule and the oxygen atom. Cohesion An attraction between molecules of the same substance. Adhesion An attraction between molecules of different substances. How does water's polarity influence its properties as a solvent? Water's polarity gives it the ability to dissolve both ionic compounds and other polar molecules. Mixture A material composed of two or more elements or compounds that are physically mixed together but not chemically combined. Solution Formed when ions gradually become dispersed in water. Solute The substance of a solution that is dissolved. Solvent The substance of a solution in which the solute dissolves. Suspensions Mixtures of water and non-dissolved material. Why is it important for cells to buffer solutions against rapid changes in pH? Buffers dissolved in life's fluids play an important role in maintaining homeostasis in organisms. pH Scale A measurement system used to indicate the concentration of H+ ions in solution. Acid Any compound that forms H+ ions in solution. Base A compound that produces hydroxide (OH-) ions in solution. Buffers Weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH. What elements does carbon bond with to make up life's molecules? Carbon can bond with many elements, including hydrogen, oxygen, phosphorus, sulfur, and nitrogen to form the molecules of life. What are the functions of each of the four groups of macro-molecules? Living things use carbohydrates as their main source of energy. Plants, some animals, and other organisms also use carbohydrates for structural purposes. Lipids can be used to store energy. Some lipids are important parts of biological membranes and waterproof coverings. Nucleic acids store and transmit hereditary, or genetic, information. Some proteins control the rate of reactions and regulate cell processes. Other form important cellular structures, while still others transport substances into or out of cells or help to fight disease. Monomers Smaller units that form polymers. Polymers Form macro-molecules by a process known as polymerization. Carbohydrates Compounds made up of carbon, hydrogen, and oxygen atoms, usually in a ratio of 1 : 2 : 1. Living things use carbohydrates as their main source of energy. Plants, some animals, and other organisms also use carbohydrates for structural purposes. Monosaccharides Single sugar molecules. Lipids Made mostly from carbon and hydrogen atoms. The common categories of lipids are fats, oils, and waxes. Lipids can be used to store energy. Some lipids are important parts of biological membranes and waterproof coverings. Nucleic Acids Macro-molecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus. Nucleic acids store and transmit hereditary, or genetic, information. Nucleotides Individual monomers of 5 carbon-carbon sugar, a phosphate group (-PO4), and a nitrogenous base that make up nucleic acids. Proteins Macro-molecules that contain nitrogen as