Chapter 4Carbon and the Molecular Diversity of

Life

p. 58-67

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

– Organic cmpnds can be small (CO2) to very large (proteins)

– 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 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 – Will form single/double bonds until valence shell

is full

Variations in C Skeletons

C chains form the skeleton of most organic molecules

– Vary in length– May be straight, bent, or

in rings

Hydrocarbons

Hydrocarbon: an organic molecule containing only carbon and hydrogen (i.e. petroleum)

– Non-polar– Hydrophobic– Many molecules have

sections of hydrocarbons (i.e. fats)

– Able to store large amounts of energy

Isomers

Isomers: compounds with same molecular formula but different structure and properties

3 types:– Structural– Geometric– Enantiomers

Structural Isomers

Differ in covalent arrangement

– As size of C skeleton increases, # possible structural isomers increases

– i.e.: C8H14 = 18 variations; while C20H42 has 366,319 variations!!

Butane Isobutane

(Both are C4H10)

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

– 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 H2O