1. Chapter 4 Carbon and the molecular diversity of life
OBJECTIVE:
Understand the properties of carbon that make it so important to life
Although cells are 70–95% water, the rest consists mostly of carbon-based compounds
Carbon: unparalleled in ability to form large complex/diverse molecules
Proteins, DNA, carbohydrates, and other molecules that distinguish living matter are all composed of carbon compounds

2. Vitalism vs Mechanism Vitalism: Belief in life force
Synthesis of complex compounds impossible
Disproved in 1953 by Miller
Mechanism: all natural phenomena governed by physical and chemical laws.

3. Sample for chemical analysis
Fig. 4-2
EXPERIMENT
“Atmosphere”
CH4
Water vapor
Electrode
NH3 H2
Condenser
Cooled water
containing
organic
molecules
Cold
water
Figure 4.2 Can organic molecules form under conditions believed to simulate those on the early Earth?
H2O
“sea”
Sample for
chemical analysis

4. CARBON Has 4 valence electrons Can form 4 covalent bonds
Versatility in bonding
Single
Double
Triple
Can form molecules of almost infinite variability

5. Name and Comment Molecular Formula Structural Formula Ball-and-
Figure 4.3
Name and Comment
Molecular
Formula
Structural
Formula
Ball-and-
Stick Model
Space-Filling
Model
(a) Methane
CH4
(b) Ethane
C2H6
Figure 4.3 The shapes of three simple organic molecules.
(c) Ethene (ethylene)
C2H4

6. CARBON What determines the chemical properties of an element? Hydrogen
(valence = 1)
Oxygen
(valence = 2)
Nitrogen
(valence = 3)
Carbon
(valence = 4)

7. 2-Methylpropane (isobutane)
Figure 4.5
(a) Length
(c) Double bond position
Ethane
Propane
1-Butene
2-Butene
(b) Branching
(d) Presence of rings
Figure 4.5 Four ways that carbon skeletons can vary.
Butane
2-Methylpropane
(isobutane)
Cyclohexane
Benzene

8. ISOMERS
Isomers: compounds with the same molecular formula but different structures and properties:
Structural isomers:
different covalent arrangements of their atoms
Geometric isomers:
same covalent arrangements, differ in spatial arrangements
Enantiomers:
isomers that are mirror images of each other

9. Isomers
Isomers are compounds with the same molecular formula but different structures and properties
Structural isomers have different covalent arrangements of their atoms
Cis-trans isomers have the same covalent bonds but differ in spatial arrangements
Enantiomers are isomers that are mirror images of each other

10. Figure 4.7 Three types of isomers
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
Figure 4.7 Three types of isomers
L isomer
D isomer
(c) Enantiomers

11. Effective Enantiomer Ineffective Enantiomer Drug Condition Pain;
Fig. 4-8
Effective
Enantiomer
Ineffective
Enantiomer
Drug
Condition
Pain;
inflammation
Ibuprofen
S-Ibuprofen
R-Ibuprofen
Figure 4.8 The pharmacological importance of enantiomers
Albuterol
Asthma
R-Albuterol
S-Albuterol

12. Functional Groups
Functional Groups: Attached to carbons skeleton and have diverse properties that dictate the behavior of organic molecules.
The seven functional groups that are most important in the chemistry of life:
Hydroxyl group
Carbonyl group
Carboxyl group
Amino group
Sulfhydryl group
Phosphate group
Methyl group

13. Estradiol Testosterone Fig. 4-9
Figure 4.9 A comparison of chemical groups of female (estradiol) and male (testosterone) sex hormones