2. LE 4-4 Hydrogen (valence = 1) Oxygen (valence = 2) Nitrogen (valence = 3) Carbon (valence = 4)

3. LE 4-5 Length Ethane Propane Butane 2-methylpropane (commonly called isobutane) Branching Double bonds Rings 1-Butene2-Butene CyclohexaneBenzene

4. LE 4-7 Structural isomers differ in covalent partners, as shown in this example of two isomers of pentane. Geometric isomers differ in arrangement about a double bond. In these diagrams, X represents an atom or group of atoms attached to a double-bonded carbon. cis isomer: The two Xs are on the same side. trans isomer: The two Xs are on opposite sides. L isomer D isomer Enantiomers differ in spatial arrangement around an asymmetric carbon, resulting in molecules that are mirror images, like left and right hands. The two isomers are designated the L and D isomers from the Latin for left and right (levo and dextro). Enantiomers cannot be superimposed on each other.

5. LE 4-10aa STRUCTURE (may be written HO—) NAME OF COMPOUNDS Alcohols (their specific names usually end in -ol) Ethanol, the alcohol present in alcoholic beverages FUNCTIONAL PROPERTIES Is polar as a result of the electronegative oxygen atom drawing electrons toward itself. Attracts water molecules, helping dissolve organic compounds such as sugars (see Figure 5.3).

6. LE 4-10ab STRUCTURE NAME OF COMPOUNDS Ketones if the carbonyl group is within a carbon skeleton EXAMPLE Acetone, the simplest ketone A ketone and an aldehyde may be structural isomers with different properties, as is the case for acetone and propanal. Aldehydes if the carbonyl group is at the end of the carbon skeleton Acetone, the simplest ketone Propanal, an aldehyde FUNCTIONAL PROPERTIES

7. LE 4-10ac STRUCTURE NAME OF COMPOUNDS Carboxylic acids, or organic acids EXAMPLE Has acidic properties because it is a source of hydrogen ions. Acetic acid, which gives vinegar its sour taste FUNCTIONAL PROPERTIES The covalent bond between oxygen and hydrogen is so polar that hydrogen ions (H + ) tend to dissociate reversibly; for example, Acetic acidAcetate ion In cells, found in the ionic form, which is called a carboxylate group.

8. LE 4-10ba STRUCTURE NAME OF COMPOUNDS Amine EXAMPLE Because it also has a carboxyl group, glycine is both an amine and a carboxylic acid; compounds with both groups are called amino acids. FUNCTIONAL PROPERTIES Acts as a base; can pick up a proton from the surrounding solution: (nonionized) Ionized, with a charge of 1+, under cellular conditions Glycine (ionized)

9. LE 4-10bb STRUCTURE (may be written HS—) NAME OF COMPOUNDS Thiols EXAMPLE Ethanethiol FUNCTIONAL PROPERTIES Two sulfhydryl groups can interact to help stabilize protein structure (see Figure 5.20).

10. LE 4-10bc STRUCTURE NAME OF COMPOUNDS Organic phosphates EXAMPLE Glycerol phosphate FUNCTIONAL PROPERTIES Makes the molecule of which it is a part an anion (negatively charged ion). Can transfer energy between organic molecules.

11. Table 4.1 Functional Groups of Organic Compounds

12. LE 4-9 Estradiol Testosterone Male lion Female lion

13. Common Elements found in living organisms

14. Molecular Composition of 2 cells

15. LE 5-2a Short polymer Unlinked monomer Dehydration removes a water molecule, forming a new bond Dehydration reaction in the synthesis of a polymer Longer polymer

16. LE 5-2b Hydrolysis adds a water molecule, breaking a bond Hydrolysis of a polymer

17. The molecules of life Carbohydrates (C,H,O)-monomer is a monosaccharide and polymers are polysaccharides Lipid-(C,H,O)-in triglycerides (polymer) the 2 monomers are glycerol and fatty acids. Steroids lipids are not monomers or polymers Proteins (C,H,O,N,S)-monomers are amino acids and the polymers are polypeptides Nucleic acids (C,H,O,N,P)-monomers are nucleotides and the polymers are polynucleotides.