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Chapter 4 Carbon and the Molecular Diversity of Life PowerPoint® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 4-2 If Miller had increased the concentration of NH3 in his experiment, how might the relative amounts of the products HCN and CH2O have differed? EXPERIMENT “Atmosphere” Water vapor CH4 Electrode Condenser Cooled water containing organic molecules H2O “sea” Sample for chemical analysis Cold water Fig. 4-4 Refer to Figure 2.9 and draw the Lewis dot structures for sodium, phosphorus, sulfur, and chlorine. Hydrogen (valence = 1) Oxygen (valence = 2) Nitrogen (valence = 3) Carbon (valence = 4) H O N C Molecular Diversity Arising from Carbon Skeleton Variation Animation: Carbon Skeletons Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 4-5a Why are these molecules called hydrocarbons? Ethane (a) Length Propane Fig. 4-5b What do these hydrocarbons illustrate? Butane (b) Branching 2-Methylpropane (commonly called isobutane) Fig. 4-6 What happens to the hydrocarbon tails of a fat molecule? Fat droplets (stained red) 100 µm (a) Mammalian adipose cells (b) A fat molecule Isomers Animation: Isomers Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 4-7a Underline/highlight why these two molecules are structural isomers. Pentane (a) Structural isomers 2-methyl butane Fig. 4-7b Highlight/underline why these two molecules are geometric isomers. cis isomer: The two Xs are on the same side. (b) Geometric isomers trans isomer: The two Xs are on opposite sides. Fig. 4-7c There are three structural isomers of C5H12. Draw the one not shown in (a). L isomer (c) Enantiomers D isomer Animation: L-Dopa Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 4-8 What is the pharmacological importance of enantiomers? Drug Condition Ibuprofen Pain; inflammation Albuterol Effective Enantiomer Ineffective Enantiomer S-Ibuprofen R-Ibuprofen R-Albuterol S-Albuterol Asthma Fig. 4-9 True or False. The function of these two molecules differ because of the number of ring structures present. Estradiol Testosterone Fig. 4-10c Organic acid or base? Carboxyl STRUCTURE Carboxylic acids, or organic acids EXAMPLE Has acidic properties because the covalent bond between oxygen and hydrogen is so polar; for example, Acetic acid, which gives vinegar its sour taste Acetic acid Acetate ion Found in cells in the ionized form with a charge of 1– and called a carboxylate ion (here, specifically, the acetate ion). NAME OF COMPOUND FUNCTIONAL PROPERTIES Fig. 4-10d Organic acid or base? Amino STRUCTURE NAME OF COMPOUND Amines EXAMPLE Acts as a base; can pick up an H+ from the surrounding solution (water, in living organisms). 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. (nonionized) (ionized) Ionized, with a charge of 1+, under cellular conditions. FUNCTIONAL PROPERTIES Fig. 4-10e How does it affect protein structure? Sulfhydryl STRUCTURE Thiols NAME OF COMPOUND (may be written HS—) EXAMPLE Two sulfhydryl groups can react, forming a covalent bond. This “cross-linking” helps stabilize protein structure. Cysteine Cysteine is an important sulfur-containing amino acid. Cross-linking of cysteines in hair proteins maintains the curliness or straightness of hair. Straight hair can be “permanently” curled by shaping it around curlers, then breaking and re-forming the cross-linking bonds. FUNCTIONAL PROPERTIES Fig. 4-10f How does its negative charge affect its ability to interact with water? Phosphate STRUCTURE Organic phosphates EXAMPLE Glycerol phosphate In addition to taking part in many important chemical reactions in cells, glycerol phosphate provides the backbone for phospholipids, the most prevalent molecules in cell membranes. Contributes negative charge to the molecule of which it is a part (2– when at the end of a molecule; 1– when located internally in a chain of phosphates). Has the potential to react with water, releasing energy. NAME OF COMPOUND FUNCTIONAL PROPERTIES Fig. 4-10g Describe the two functional properties of the methyl group Methyl STRUCTURE Methylated compounds EXAMPLE NAME OF COMPOUND FUNCTIONAL PROPERTIES 5-Methyl cytidine 5-Methyl cytidine is a component of DNA that has been modified by addition of the methyl group. Fig. 4-Predict which of the following molecules would be the stronger acid. Explain your answer.