1. Review the Chemistry of Life, Proteins and Nucleic Acids Nestor T. Hilvano, M.D., M.P.H.

2. Learning Objectives 1. Define an atom, element, molecule and compound. 2. List the major chemical elements of the human body. 3. Describe the types of chemical bonds. 4. Describe the major types of chemical reactions. 5. Discuss the structures and functions of carbohydrates, lipids, proteins, and nucleic acids. 6. Explain how enzymes function.

3. The Chemical Elements Element = simplest form of matter (made up of atoms) with unique chemical properties 92 elements occur in nature 96.5% of human body – C,O,H,N Trace elements in minute amount

4. Atomic Structure Atom- particle (piece) of element 3 Subatomic particles – protons, neutrons, & electrons Nucleus = center of atom –protons (p+) and neutrons (n˚) Electron shells surround the nucleus –Electrons (e-)

5. Molecules and Chemical Bonds Molecules- combination of 2 or more atoms (ex. O 2 ). Compounds- different elements bonded together (ex. H 2 O); compounds are all molecules, however not all molecules are compounds Chemical bonds: a) ionic bonds- attraction of ions of opposite charges (weak bonds); Ions are atoms with an electrical charge resulting from a gain of e - (anions, negative charged); or loss of e - (cations, positive charged) b) covalent bonds- strong electron bonds, atoms share pair/s outer electrons c) H (hydrogen) bonds- weak polar bonds between water molecules

6. Covalent Bonds Formed by sharing of valence electrons Types of covalent bonds –single = sharing of single pair electrons (H-H) –double = sharing of 2 pairs (C=O) –Nonpolar covalent bonds (equal sharing of e-, strongest of all bonds) i.e. H 2, O 2, CH 4 –Polar covalent bonds (unequal sharing of e-, weak bonds) i.e. H2O

7. Organic Compounds: Carbohydrates General formula - (CH 2 O) n Monosaccharides (simple sugar) - C 6 H 12 O 6 a. glucose – chief source of energy b. galactose – milk products c. fructose – fruits

8. Disaccharides Major disaccharides (two sugars) a. sucrose = table sugar Glucose + Fructose b. Lactose = sugar in milk Glucose + Galactose c. Maltose = grain products Glucose + Glucose

9. Polysaccharides Chains of sugar subunits (many sugars) a. Starch - energy storage in plants b. Cellulose - structural molecule of plant’s cell walls c. Glycogen - energy storage in animals (liver and skeletal muscle)

10. Organic Molecules: Lipids Hydrophobic organic molecule –composed of carbon, hydrogen and oxygen –Includes fats, oils, and waxes Five primary types in humans –Fatty acids –Triglycerides –Phospholipids –Eicosanoids (leukotrienes & prostaglandins) –Steroids

11. Fatty Acids Chain of 4 to 24 carbon atoms Classified –saturated - carbon atoms saturated with hydrogen –unsaturated - contains C=C bonds without hydrogen

12. Triglycerides (Neutral Fats) 3 fatty acids bonded to glycerol molecule Function - energy storage, insulation and protection In blood circulation

13. Phospholipids Triglyceride with one fatty acid replaced by a phosphate group primary component of cell (plasma) membrane. Amphiphilic character –fatty acid “tails” are hydrophobic –Phosphate “head” is hydrophilic

14. Steroids and Cholesterol Steroid = lipid with carbon atoms in four rings –cortisol, progesterone, estrogens,testosterone and bile acids Cholesterol –component of cell membranes –produced only in animal liver cells naturally produced by our body

15. Organic Molecules: Proteins Protein = polymer of amino acids Amino acid structure contains a central carbon atom, hydrogen atom, amino group, carboxyl group, and a R group (variable side chain)

16. Protein Structure and Shape Primary structure –Linear sequence of amino acids Secondary structure –Hydrogen bonds form helixes (coils) or pleated sheets shape Tertiary structure –further folding and bending of secondary structure into unique fibrous and globular shapes Quaternary structure –associations of two or more separate polypeptide chains; several tertiary structures together forming the protein

17. Protein Functions Support (integral proteins) Coordination and control (hormones) Membrane Transport (carrier proteins) Metabolic regulation (enzymes) Defense (antibodies) Movement (actin and myosin filaments) Cell adhesion (desmosomes)

18. Enzyme structure and function Proteins as biological catalyst Substrate - substance an enzyme acts upon Characteristics: - specificity - saturation limits - regulation (turn it on or off)

19. Nucleic Acids Building block = nucleotides DNA –Contains genetic codes (inherited characteristics) RNA – 3 types –m-RNA, t-RNA, r-RNA –involved in protein synthesis coded for by DNA

20. Nitrogenous Bases Purines - double ring - Guanine (G) - Adenine (A) Pyrimidines - single ring - Uracil (U) (only in RNA) - Thymine (T) (only in DNA) - Cytosine DNA base pairs = A-T; C-G RNA base pairs = A-U; C-G Example: Replication =DNA to DNA: ACT --- TGA Transcription=DNA to mRNA: ACT --- UGA Translation= mRNA to tRNA: UGA --- ACU