CHEMISTRY OF LIFE

1. CHEMISTRY OF LIFE Chapter 2

2. Levels of Chemical Organization • Matter – anything that occupies space and has mass • Molecules – particles of matter made up of atoms • Atoms – protons, neutrons, electrons

3. A Model Of The Atom

4. Atomic number is equal to the number of protons Atomic mass is equal to the number of protons plus neutrons

5. IsotopesSame atomic number but different atomic mass

7. Compounds

8. CHEMICAL BONDING • Ionic bond – strong electrical attraction between ions that bare opposite electrical charges (Fig. 2-2); ionic molecules dissolve easily in water (dissociate) • Covalent bond – bond formed between two atoms that share a pair of electrons (Fig. 2-3)

9. Ionic Bond

10. Covalent Bond

11. Polar vs. Nonpolar Covalent Bonds • Polar Covalent Bond – electrons are not shared equally (ex. H2O) • Non Polar Covalent Bond – electrons are shared equally (ex. C-H)

12. Polar Covalent Bond

13. Inorganic Chemistry • Molecules that generally do not contain carbon; there are no C-H or C-C bonds; smaller than organic molecules • H2O is an inorganic molecule – “universal solvent” • Organisms are composed mainly of water

14. Dehydration Synthesis – chemical reaction in which 2 molecules become covalently bonded by removing –H from one and –OH from another, removed atoms form water(Fig. 2-4)

15. Hydrolysis – the breaking apart of a molecule into its monomer subunits by the addition of the components of a H2O molecule into each of the covalent bonds linking the monomers

16. Acids, Bases & Salts – Fig. 2-5 • Acid – a substance that releases H+ (hydrogen ions); pH<7 • Base (alkaline) – a substance that releases OH- (hydroxide ions) or decreases H+ ; pH>7 • Salt – substance composed of positively charged ions (not H+ ) and negatively charged ions (not OH-); usually neutral • Buffers – substances that react with strong acid or base to keep pH constant by absorbing or releasing H+ or OH- as needed; helps to maintain homeostasis

17. pH Scale

18. Organic Chemistry – Table 2-3Molecules contain H-C & C-C bonds • Carbohydrates – carbon + water – Fig. 2-6 • glycogen – animals store energy in this carb. • Starch – plants store energy in this carb.

19. Lipids – fats, oils and waxes – non polar, therefore they do not dissolve appreciably in water – Fig. 2-7, 2-8 • Phospholipids – major component of cell membranes • Triglycerides – energy storage • Cholesterol – steroid lipid – component of cell membrane; precursor to steroid hormones

20. Phospholipid Triglyceride

22. Proteins - most varied of all the organic molecules in function; enzymes, structural, hormones, immunological, membrane components – building blocks are amino acids • Enzyme – protein that acts as a catalyst – Fig. 2-10 • Co-enzyme – some enzymes don’t function unless a co-enzyme is present (vitamins may serve this function)

23. Nucleic Acids – DNA and RNA (genetic material) Fig. 2-11