Chapter 4 Carbon and the Molecular Diversity of Life PowerPoint Lectures for Biology Seventh Edition Neil Campbell and Jane Reece EXPERIMENT Atmosphere Stanley Miller Experiment 1953 CH4 Water vapor Electrode NH 3 Simulated the process by which organic compounds may have been produced from inorganic precursors during earth s early formation Fig 4 2 H2 Condenser Cooled water containing organic molecules H2O sea Sample for chemical analysis Cold water The Bonding Versatility of Carbon Allows it to form many diverse molecules including carbon skeletons or backbone Name Molecular Formula Structural Formula Ball and Stick Model Space Filling Model a Methane b Ethane c Ethene ethylene Fig 4 3 The electron configuration of carbon Gives it covalent compatibility with many different elements Hydrogen valence 1 Oxygen valence 2 Nitrogen valence 3 Carbon valence 4 H O N C Fig 4 4 Carbon atoms can partner with atoms other than hydrogen for example Carbon dioxide CO2 O C O Urea CO NH2 2 Copyright 2008 Pearson Education Inc publishing as Pearson Benjamin Cummings H a Length H H C C H H H H H H H C C C H H H Ethane H Propane H C H b Branching H H H H H C C C C H H H H H H H Butane c Double bonds H H H H C C C C H H C d Rings Figure 4 5 A D H H H C C C C Cyclohexane Copyright 2005 Pearson Education Inc publishing as Benjamin Cummings C C H H H H H H H H C C C C H H 2 Butene H H C C H 1 Butene H H H 2 methylpropane commonly called isobutane H H H H H H H H C C C C C Benzene H H Hydrocarbons Tails in a Fat Molecule Makes fats hydrophobic Fat droplets stained red Figure 4 6 A B a A fat molecule 100 m b Mammalian adipose cells Fig 4 7 Pentane 2 methyl butane a Structural isomers cis isomer The two Xs are on the same side trans isomer The two Xs are on opposite sides b Geometric isomers L isomer c Enantiomers D isomer Enantiomers Drug Condition Ibuprofen Pain inflammation Albuterol Fig 4 8 Effective Enantiomer Ineffective Enantiomer S Ibuprofen R Ibuprofen R Albuterol S Albuterol Asthma Enantiomers L Dopa D Dopa effective against Parkinson s disease biologically inactive Fig 4 9 Estradiol Testosterone Fig 4 10a CHEMICAL GROUP Hydroxyl Carbonyl Carboxyl STRUCTURE may be written HO NAME OF COMPOUND In a hydroxyl group OH a hydrogen atom is bonded to an oxygen atom which in turn is bonded to the carbon skeleton of the organic molecule Do not confuse this functional group with the hydroxide ion OH The carbonyl group CO consists of a carbon atom joined to an oxygen atom by a double bond When an oxygen atom is double bonded to a carbon atom that is also bonded to an OH group the entire assembly of atoms is called a carboxyl group COOH Alcohols their specific names usually end in ol Ketones if the carbonyl group is within a carbon skeleton Carboxylic acids or organic acids Aldehydes if the carbonyl group is at the end of the carbon skeleton EXAMPLE Ethanol the alcohol present in alcoholic beverages Acetone the simplest ketone Acetic acid which gives vinegar its sour taste Propanal an aldehyde FUNCTIONAL PROPERTIES Is polar as a result of the electrons spending more time near the electronegative oxygen atom A ketone and an aldehyde may be structural isomers with different properties as is the case for acetone and propanal Can form hydrogen bonds with water molecules helping dissolve organic compounds such as sugars These two groups are also found in sugars giving rise to two major groups of sugars aldoses containing an aldehyde and ketoses containing a ketone Has acidic properties because the covalent bond between oxygen and hydrogen is so polar for example 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 Fig 4 10b CHEMICAL GROUP Amino Sulfhydryl Methyl In a phosphate group a phosphorus atom is bonded to four oxygen atoms one oxygen is bonded to the carbon skeleton two oxygens carry negative charges The phosphate group OPO32 abbreviated P is an ionized form of a phosphoric acid group OPO3H2 note the two hydrogens A methyl group consists of a carbon bonded to three hydrogen atoms The methyl group may be attached to a carbon or to a different atom may be written HS STRUCTURE NAME OF COMPOUND Phosphate The amino group NH2 consists of a nitrogen atom bonded to two hydrogen atoms and to the carbon skeleton The sulfhydryl group consists of a sulfur atom bonded to an atom of hydrogen resembles a hydroxyl group in shape Amines Thiols Organic phosphates Methylated compounds EXAMPLE 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 Acts as a base can pick up an H from the surrounding solution water in living organisms nonionized ionized Ionized with a charge of 1 under cellular conditions Glycerol phosphate Cysteine Cysteine is an important sulfur containing amino acid 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 Two sulfhydryl groups can react forming a covalent bond This cross linking helps stabilize protein structure 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 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 Has the potential to react with water releasing energy 5 Methyl cytidine 5 Methyl cytidine is a component of DNA that has been modified by addition of the methyl group Addition of a methyl group to DNA or to molecules bound to DNA affects expression of genes Arrangement of methyl groups in male and female sex hormones affects their shape and function ATP An Important Source of Energy for Cellular Processes One phosphate molecule adenosine triphosphate ATP is the primary energytransferring molecule in the cell ATP consists of an organic molecule called adenosine attached to a string of three phosphate groups Adenosine Copyright 2008 Pearson Education Inc publishing as Pearson Benjamin Cummings Reacts with H2O P P P Adenosine ATP Pi P Inorganic phosphate P Adenosine ADP Energy You should now be able to 1 Explain how carbon s electron configuration explains its ability to form large complex diverse organic
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