1. Carbon and the Molecular Diversity of Life
Chapter 4
Carbon and the Molecular Diversity of Life

2. Organic Chemistry
Although cells are 70–95% water, the rest consists mostly of carbon-based compounds
Carbon is unparalleled in its ability to form large, complex, and diverse molecules
Proteins, DNA, carbohydrates, and other molecules that distinguish living matter are all composed of carbon compounds
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3. Sample for chemical analysis
Fig. 4-2
EXPERIMENT
“Atmosphere”
CH4
Water vapor
Electrode
NH3 H2
Condenser
Cooled water
containing
organic
molecules
Cold
water
Can organic molecules form under conditions believed to simulate those on the early Earth? Read figure 4.2 in your textbook including the results and conclusions.
USEFUL ANIMATION:
H2O
“sea”
Sample for
chemical analysis

4. Electron configuration is the key to an atom’s characteristics
Concept 4.2: Carbon atoms can form diverse molecules by bonding to four other atoms
Electron configuration is the key to an atom’s characteristics
Electron configuration determines the kinds and number of bonds an atom will form with other atoms
With four valence electrons, carbon can form four covalent bonds with a variety of atoms
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5. Valence: Number of covalent bonds an atom will usually form.
Valences
Valence: Number of covalent bonds an atom will usually form.
Usually equal to the number of electrons needed to complete the outermost shell.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

6. Molecular Formula Structural Formula Ball-and-Stick Model
Fig. 4-3
Molecular Formula
Structural Formula
Ball-and-Stick
Model
Space-Filling
Model
Name
(a) Methane
(b) Ethane
When two carbon atoms are joined by a double bond, it will produce a flat shape.
(c) Ethene
(ethylene)

7. Major components of petroleum.
Hydrocarbons
Major components of petroleum.
Many organic compounds have regions that consist only of these.
Ex. Fats have long hydrocarbon tails that are nonpolar attached to a polar head.
Store a relatively large amount of energy.
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8. Hydrocarbons
Hydrocarbons are organic molecules consisting of only carbon and hydrogen – they illustrate the diversity of the carbon skeletons of organic molecules.
Many organic molecules, such as fats, have hydrocarbon components
Hydrocarbons can undergo reactions that release a large amount of energy
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9. The Role of Hydrocarbons in Fat: Triglycerides
Black = carbon
Gray = hydrogen
Red = oxygen
Triglycerides are fat molecules consists of a headpiece and 3 hydrocarbon tails – the tails store energy and account for the hydrophobic behavior of fats.
Mammalian adipose cells stockpile fat molecules as a fuel reserve.

10. Isomers
Isomers are compounds with the same molecular formula but different structures and therefore different properties:
Structural isomers
Geometric isomers
Enantiomers
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11. Structural Isomers Differ in the covalent arrangement of their atoms.
May also differ in the location of double bonds.
As the carbon skeleton increases in size, the number of possible isomers increases tremendously.
Differ in covalent partners & possibly location of double bonds: butane and isobutane
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

12. Geometric Isomers
Have the same covalent partnerships, but differ in their spatial arrangements.
Arise from the inflexibility of double bonds – will not allow the atoms they join to rotate freely about the bond axis (unlike single bonds).
Differ in arrangement about a double bond.
This slight difference in shape can dramatically affect the biological activity of the molecules.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

13. Enantiomers Molecules that are mirror images of each other.
Usually, these “right-handed” and “left-handed” versions of the same molecule allow for one to be biologically active and the other inactive.
Ex. Thalidomide
Differ in spatial arrangement around an asymmetric carbon.
Results in molecules that are mirror images, like left and right hands.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

14. The Pharmacological Importance of Enantiomers
Two enantiomers of a drug may not be equally effective (and in some cases, produce harmful effects).
Thalidomide was prescribed for pregnant women in the late 50’s – a drug that was a mixture of two enantiomers.
One enantiomer reduced morning sickness
The other caused severe birth defects
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

15. 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 - two enantiomers of a drug may have different effects
Albuterol
Asthma
R-Albuterol
S-Albuterol

16. 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
(c) Enantiomers

17. Functional Groups
Functional groups are the components of organic molecules that are usually involved in chemical reactions.
Each group behaves consistently from one organic molecule to another.
The number and arrangement of functional groups help give each molecule its unique properties.
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18. Functional Groups
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
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19. Text pg. 64-65…KNOW THE CHART!

20. A Comparison of Functional Groups
Two molecules differ mainly in the attachment of functional groups to a common carbon skeleton.
These subtle variations in molecular architecture (shaded in blue and pink) influence the development of the anatomical and physiological differences between female & male vertebrates.
Sexuality has a biological basis in variations of molecular architecture!
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21. ATP: An Important Source of Energy for Cellular Processes
One phosphate molecule, adenosine triphosphate (ATP), is the primary energy-transferring molecule in the cell
ATP consists of an organic molecule called adenosine attached to a string of three phosphate groups
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22. ATP: An Important Source of Energy for Cellular Processes
Adenosine triphosphate, or ATP, is the primary energy-transferring molecule in the cell.
ATP consists of an organic molecule called adenosine attached to a string of three phosphate groups.
Where three phosphate groups are present in a series, as in ATP, one phosphate may split off as an inorganic phosphate ion (abbreviated as Pi). This process is known as the HYDROLYSIS of ATP.
Losing one phosphate, ATP becomes ADP (adenosine diphosphate).
The reaction releases energy that can be used by the cell.

23. You should now be able to:
Explain how carbon’s electron configuration explains its ability to form large, complex, diverse organic molecules.
Distinguish among the three types of isomers: structural, geometric, and enantiomer. Discuss the biological importance of isomers.
Identify the 7 main functional groups and the characteristics of each.
Explain how ATP functions as the primary energy transfer molecule in living cells.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings