Chapter 4 Carbon and the Molecular Diversity of Life p

Carbon Carbon (C) is the basis of large, complex, & diverse molecules that make up living organisms

Importance of Carbon Cells are composed of C-based compounds – Proteins – DNA – Lipids – Carbohydrates Other cell ingredients include H, O, N, P, S – Along w/C, are found in relatively same proportions in all organisms

Organic Chemistry is the Study of Carbon Compounds Compounds containing Carbon are called Organic –O–Organic cmpnds can be small (CO 2 ) to very large (proteins) –O–Organic cmpnds found in living organisms can now be synthesized in a laboratory (i.e. acetic acid)

C Atoms are Versatile Building Blocks C’s electron configuration determines its bonding properties –4–4 valence e - cause C to form 4 covalent bonds with other atoms (“tetravalence”)

Carbon Molecule Shapes A molecules shape often determines its function When C forms 4 single bonds, takes on tetrahedron shape When C=C, molecule lies flat

The e - configuration of C allows it to easily form covalent bonds with H, O, N, & other C –W–Will form single/double bonds until valence shell is full

Variations in C Skeletons C chains form the skeleton of most organic molecules –V–Vary in length –M–May be straight, bent, or in rings

Hydrocarbons Hydrocarbon: an organic molecule containing only carbon and hydrogen (i.e. petroleum) –N–Non-polar –H–Hydrophobic –M–Many molecules have sections of hydrocarbons (i.e. fats) –A–Able to store large amounts of energy

Isomers Isomers: compounds with same molecular formula but different structure and properties 3 types: –S–Structural –G–Geometric –E–Enantiomers

Structural Isomers Differ in covalent arrangement –A–As size of C skeleton increases, # possible structural isomers increases –i–i.e.: C 8 H 14 = 18 variations; while C 20 H 42 has 366,319 variations!! Butane Isobutane (Both are C 4 H 10 )

Geometric Isomers Differ in their spatial arrangement – Due to inflexibility of double bonds – Can affect function (i.e.: vision)

Enantiomers Molecules that are mirror images of each other Caused by an Asymmetric Carbon: a C bonded to 4 different atoms/molecules –M–May have drastic effect on the function of the molecule (i.e.: thalidomide)

Functional Groups Functional Groups: attachments to C skeletons that are involved in chemical reactions -Behave consistently from molecule to molecule -All are hydrophilic, so they help increase the solubility of organic molecules in H 2 O