Chapter 4 Carbon and the Molecular Diversity of Life

! Diversity of Life Period Name Chapter 4: Carbon and the Molecular Diversity of Life Concept 4.1 Organic chemistry is the study of carbon compounds 1. Study this figure of Stanley MillerÕs experiment to simulate conditions thought to have existed on the early Earth. Explain the elements of this experiment, using arrows to indicate what occurs in various parts of the apparatus. The water mixture in the ÒseaÓ at the bottom of the ßask was heated; thus vapor entered the ÒatmosphereÓ of the ßask , containing a mixture of hydrogen gas, methane, ammonia, and water vapor. Sparks were discharged to mimic lightning. A condenser cooled the Òatmosphere,Ó raining water molecules down into the ÒseaÓ. As material cycled through the apparatus, Miller periodically collected samples for analysis . 2. What was collected in the sample for chemical analysis? What was concluded from the results of this Miller collected several organic compounds, both simple (such as formaldehyde) experiment? and complex (such as hydrocarbons), commonly found in organisms. Though his methodology is not undisputed, his results support the concept hat abiotic synthesis of organic compounds could have been an early stage in the origin of life. Concept 4.2 Carbon atoms can form diverse molecules by bonding to four other atoms 3. Make an electron distribution diagram of carbon. It is essential that you know the answers to these questions: a. How many valence electrons does carbon have? b. How many bonds can carbon form? Carbon has 4 valence electrons, can bond to 4 items, and typically forms covalent bonds with other elements. b. What type of bonds does it form with other elements? 4. Carbon chains form skeletons. List here the types of skeletons that can be formed. Carbon skeletons vary in length. The skeleton may have double bonds, which can vary in location. Skeletons may be branched or unbranched. Some carbon skeletons are arranged in rings. 5. What is a hydrocarbon? Name two. Are hydrocarbons hydrophobic or hydrophilic? Hydrocarbons are hydrophobic molecules consisting of only carbon and hydrogen, such as benzene and methane. ! -1- ! Chapter 4: Carbon and the Molecular Diversity of Life 6. In Chapter 2 you learned what an isotope is. Since students often confuse this word with isomer, please define each term here and give an example. Definition ! isotope isomer 7. Example An isotope is an alternative form of the same element containing an equal ! number of protons but a different number of neutrons in its atomic nucleus, and thus some different properties An isomer is an alternative form of the same compound with the same ! formula but a different arrangement of atoms in the molecule, and thus different properties C-12, C-13 and C-14 are isotopes of the element carbon Pentane and 2-methylbutane are structural isomers of each other. Use this figure to identify the three types of isomers. For each type, give a key character and an example. Pentane and 2-methylbutane are structural isomers that differ in their atom covalent conÞgurations and double bond positions. Ibuprofen enantiomers are called L or D after the Latin words for left and right (levo and dextro) respectively. 8. Give one example of enantiomers that vary in their pharmacological effect. Albuterol is used to relax bronchial muscles, improving airßow in asthma patients. Only the effective R-Albuterol is marketed as the ineffective S-Albuterol form counteracts the active R form. Concept 4.3 A small number of chemical groups are key to the functioning of biologic l molecules 9. Here is an idea that will recur throughout your study of the function of molecules: Change the structure, change the function. You see this in enantiomers, you will see it in proteins and enzymes, and now we are going to look at testosterone and estradiol. Notice how similar these two molecules are, and yet you know what a vastly different effect each has. Label each molecule in the sketch below, and circle the differences. Testosterone Estradiol 10. Define functional group. Functional groups affect molecular function by being directly involved in chemical reactions. ! -2- ! Chapter 4: Carbon and the Molecular Diversity of Life 11. There are seven functional groups. Complete the following chart. ! Hydroxyl Carbonyl Carboxyl Amino Sulfhydryl Phosphate Methyl (ÐOPO32): P atom S atom ! ! C bonded to three bonded to four O atoms; H atoms; not bonded to H one O bonded to the C necessarily attached to a C skeleton; two Os carry atom atom negative charges ! ! ! ! ! ! glycerol ! Example acetic acid cytidine acetone ethanol glycine cysteine phosphate ! ! ! ! ! ! Functional ! hydrophilic hydrophilic hydrophilic hydrophilic hydrophilic hydrophilic not reactive Properties Structure ! (ÐOH): H atom bonded to an O atom bonded to the C skeleton ! (>CO): C atom joined to an O atom by a double bond (ÐNH2): N atom ! !(ÐCOOH): O atom ! double-bonded to a C bonded to two H atom also bonded to atoms and to the C an ÐOH group skeleton 12. You will need to master the chart and the information in it. Using the functional groups above, see if you can answer the following prompts: Amino groups a. ÐNH2 b. Can form cross-links that stabilize protein structure Sulfhydryl c. Key component of ATP Phosphate d. Can affect gene expression e. CH3 Methyl Methyl f. Is always polar Hydroxyl g. Determines the two groups of sugars h. Has acidic properties i. ÐCOOH Carbonyl Carboxyl Carboxyl Amino groups j. Acts as a base k. Circle and identify three functional groups in the molecule shown above. Hydroxyl, Carboxyl, and Amino groups Testing Your Knowledge: Self-Quiz Answers Now you should be ready to test your knowledge. Place your answers here: 1. ! 2. 3. 4. 5. 6. 7. -3-