Chapter 2 Notes

Chapter 2: Chemical Basis of Life I. Chemistry- study of matter and how it changes; very basis of living matter II. Matter- anything that has mass and occupies space A. Three states of matter: 1. Solid- particles are tightly packed together; has a definite shape and size 2. Liquids- particles are loosely packed together; takes the shape of its container 3. Gas- particles are very spread out, does not have a definite shape B. Atoms- building blocks of matter C. Elements- matter made up of only one kind of atom D. Compound- matter made up of different kinds of atoms linked together III. Atoms A. Smallest unit of an element that retains all the properties of that element B. Sub-Atomic Particles 1. Protons- positive charge; located inside the nucleus of atom 2. Neutrons- neutral charge; located inside the nucleus of an atom 3. Electrons- negative charge; located in energy levels surrounding nucleus IV. Elements A. A substance composed of only one type of atom B. Cannot be broken down by ordinary means C. There are 92 naturally occurring elements 1. Carbon, Hydrogen, Oxygen, and Nitrogen make up 95% of the human body 2. The other 88 are trace elements; required in minute amounts D. Carbon- most important element; chemical compound necessary for life are composed of Carbon E. Biologically Important Elements 1. Oxygen (O) 2. Carbon (C) 3. Hydrogen (H) 4. Nitrogen (N) 5. Calcium (Ca) 6. Phosphorus (P) 7. Sulfur (S) 8. Potassium (K) 9. Chlorine (Cl) 10. Sodium (Na) 11. Magnesium (Mg) 12. Iodine (I) 13. Iron (Fe) V. Periodic Table A. Lists the elements in order by their weights (lightest to heaviest) B. Rows are called periods; all elements in each row belong to the same period C. Columns are called groups or families; share some of the same properties 1. Properties help identify elements 2. Properties include state, color, and smell D. Atomic number- number of protons in an atom

E. Atomic mass- number of protons plus neutrons in an atom F. Isotopes- atoms of the same element with a different number of neutrons G. Energy Level- identifies the amount of potential energy an electron has VI. Chemical Bonding A. Atoms react with each other depending on the electrons in the outer energy levels B. There are several types of chemical bonds 1. Covalent- strongest bond; formed by the sharing of valence electrons (last energy level) 2. Ionic- formed by the transfer of electrons from one atom to another; atom that gains electrons is negative, atom that loses electron is a positive ion 3. Hydrogen Bond- weakest bond; formed when Hydrogen is covalently bonded to an electronegative atom VII. Properties of Water A. Water is a solvent B. Used more than any other solvent C. Cohesive- hydrogen bonds hold molecules of water together 1. Ex. Water sticks to water D. Adhesive- different molecules bond to molecules of water 1. Ex. Kool-Aid sticks to water E. High Specific Heat 1. Hydrogen bonds absorb heat when they break and release heat when they form a. Temperature change is minimal 2. Water stabilizes body temperature as well as environment F. Heat Boiling Point 1. It takes a great deal of energy to break hydrogen bonds since water molecules have a strong attraction to each other a. When bonds break water converts to gas and evaporates. This keeps us from dehydrating G. Good Evaporative Coolant 1. As the body sweats, the water evaporates. This take s heat out of the body. VIII. Chemical Reactions A. A chemical reaction occurs when the bonds are formed or broken between atoms, ions or molecules 1. Those changed by the reactions are the reactants, those formed are thee products a. Synthesis- when two or more atoms or molecules are joined b. Decomposition- larger molecules are broken into smaller ones c. Exchange reaction- occurs as parts of molecules trade places d. Reversible reaction- reaction can occur going either way; symbolized by using two arrows B. Catalyst- influences the rates of chemical reactions IX. Acids and Bases A. Electrolytes- substances that release ions in water 1. Acids- electrolytes that release hydrogen ions (H+) 2. Bases- substances that release ions that combine with Hydrogen ions 3. pH- represents the concentration of hydrogen ions (H+) in solutions

4. A pH of 7 indicates a neutral solution with equal numbers of H+ and hydroxyl ions (OH-) 5. A pH greater than 7 is a base; less than 7 is an acid 6. Between each whole number of the pH scale there is a 10-fold difference in H+ concentration X. Chemical Constituent of Cells A. Inorganic Substances 1. Water- the most abundant compound in living things; makes up 2/3 of the weight of adults -Most metabolic reactions occur in water -Transports material by blood - Carries waste materials; absorbs and transports heat 2. Oxygen- needed to release energy from nutrients and is used to drive cells metabolism 3. Carbon Dioxide- released as a waste product during energy releasing metabolic reactions 4. Inorganic Salts- the sources of ions of Na, Cl, K, Ca, Mg, P, Carbonate, Bicarbonate, and Sulfate - Play important roles in metabolic processes B. Organic Substances 1. Carbohydrates- provide energy for cellular activity a. Molecules contain C, H, O b. Made from monosaccharide (simple sugar) 1. Disaccharides- two monosaccharide joined together 2. Polysaccharides- complex carbohydrate such as starch that are built out of many monosaccharides a. Human synthesizes the polysaccharides glycogen and uses it for fuel 2. Lipids- insoluble in water and include fats, phospholipids and steroids a. Fats supply energy and are composed of C, H, and O. They are built from glycerol and three fatty acid chains b. Fatty acids with hydrogen at every position along the carbon chain are saturated 1. Those with one or more double bonds are unsaturated a. Phospholipids- contain glycerol, two fatty acids and a phosphate group and are important to cell structure b. Steroids- complex ring structures, including cholesterol, which used to synthesize sex hormones 3. Protein a. Have a variety of functions including structural materials, energy sources, contain hormones, receptions on cell membranes, antibodies, and enzymes to catalyze metabolic reactions b. Contain C, H, O, N atoms; some contain sulfur c. Building blocks of proteins are amino acids. Each of which has a carboxyl and amino group

d. Proteins have complex shapes held together by hydrogen bonds. They also determine how proteins functions and can be altered (denatured) by pH, temperature, radiation, or chemicals 4. Nucleic Acids a. Form genes; take part in protein synthesis b. Contain C, H, O, N, and P which are bound into building blocks called nucleotides c. RNA (ribonucleic acid) -functions in protein synthesis d. DNA -stores the molecular code in genes