LE 4-4

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

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

4. Structural isomers differ in covalent partners, as shown in this example of two isomers of pentane. LE 4-7 cis isomer: The two Xs are on the same side. trans isomer: The two Xs are on opposite sides. 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. 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. STRUCTURE LE 4-10aa (may be written HO—) Ethanol, the alcohol present in alcoholic beverages NAME OF COMPOUNDS FUNCTIONAL PROPERTIES Is polar as a result of the electronegative oxygen atom drawing electrons toward itself. Alcohols (their specific names usually end in -ol) Attracts water molecules, helping dissolve organic compounds such as sugars (see Figure 5.3).

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

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

8. EXAMPLE STRUCTURE LE 4-10ba Glycine 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 NAME OF COMPOUNDS Acts as a base; can pick up a proton from the surrounding solution: Amine (nonionized) (ionized) Ionized, with a charge of 1+, under cellular conditions

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

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

11. Table 4.1 Functional Groups of Organic Compounds

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

13. Common Elements found in living organisms

14. Molecular Composition of 2 cells

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