1. Chapter 2 The Chemistry of Life

2. 2-1 The Nature of Matter Living things are made of chemical compounds Atom = the basic unit of matter - made of protons (positive), electrons (negative), and neutrons (neutral) - Atomic number = # of protons - Atomic mass = protons plus neutrons

3. Element = a pure substance that consists of just one kind of atom - Isotopes = atoms of the same element with different # of neutrons - example: carbon 12, 13, 14 - Isotopes have the same # of electrons so they have the same chemical properties

4. - Radioactive Isotopes – Have unstable nuclei and break down at a constant rate over time… used to determine age of rocks and fossils, treat cancer, and kill bacteria

5. Compound = two or more elements bonded in definite proportions. - example: H 2 O, NaCl Chemical Bonds – involves valance electrons

6. - Ionic bond = one or more electrons are transferred from one atom to another, then opposite charges attract two ions

7. - Covalent bond = electrons are shared between atoms - Molecule = when atoms are joined together by covalent bonds

8. - Van der Waals Forces = slight attraction between oppositely charged regions of nearby molecules

9. 2-2 Properties of Water Water is the single most abundant compound in most living things. Properties - Water expands as it freezes… ice floats on liquid water

10. - Polarity – oxygen atom attracts shared electrons stronger than the hydrogen atoms - causes hydrogen bonds – attraction between slightly + and – - cohesion = attraction between molecules of same substance; allows beading of water and surface tension - adhesion = attraction between molecules of different substances; meniscus and capillary action Water properties website

11. Solutions and suspensions - mixture = two or more elements physically mixed - solution = mixture with evenly distributed molecules - solute = dissolved substance - solvent = substance in which solute is dissolved - suspension = mixtures of water and nondissolved material

13. Acids, Bases and pH - Water can split to form ions H 2 O  H+ + OH- the ions are equal so water is neutral

14. - pH scale = indicates the concentration of hydrogen ions (H+) - acids = form H+ ions in water; pH value lower than 7 - bases = form OH- ions in water; pH value higher than 7 - buffers = weak acids or bases that can react with strong acids or bases to prevent changes in pH

16. 2-3 Carbon Compounds Carbon has four valence electrons and forms strong chains or rings Macromolecules means “giant molecules” - formed by a process of polymerization - monomers = small units which are joined to form polymers

17. - Carbohydrates = main source of energy and used for structure - made of carbon, hydrogen and oxygen, ratio 1:2:1 - monomers = sugars or monosaccharides; glucose - polymers = starches or polysaccharides; glycogen, cellulose

18. Starch Glucose

19. - Lipids = energy storage, insulation, makes up membranes - made of carbon, hydrogen and oxygen - examples: fats, oils, and waxes - saturated – no double bonds… butter - unsaturated – has double or triple bonds… olive oil - steroids – chemical messengers

21. - Nucleic acids = store and transmit hereditary information - made of hydrogen, oxygen, carbon, and phosphorus - monomers = nucleotides

22. - Proteins = control rate of chemical reactions, regulate cell processes, form bone and muscle, transport substances, fight diseases - made of nitrogen, carbon, hydrogen, and oxygen - monomers = amino acids; 20 different a.a. in nature

23. General structureAlanineSerine Amino groupCarboxyl group Amino Acid Structure

24. Proteins form certain structures Amino acids

26. 2-4 Chemical Reactions and Enzymes Chemical reaction = process that changes, or transforms, one set of chemicals into another. - Equation: reactants  products

27. - Endothermic reaction = requires energy - Exothermic reaction = releases energy; can occur spontaneously - Activation energy = needed for most reactions to occur

28. Enzymes = proteins that act as biological catalysts, which speed up chemical reactions in the body… lowers activation energy - usually specific to reaction and not used up in reaction

29. - Enzyme-substrate complex = site where reactants are brought together to react; fit like a lock and key - Enzymes work in specific range of conditions: pH, temp