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

2. Carbon Chemistry
Carbon is the Backbone of Biological Molecules (macromolecules)
All living organisms are made up of chemicals based mostly on the element carbon
Figure 4.1

3. Stanly Miller Experiment
Could organic compounds have been synthesized abiotically on the early Earth?

4. Carbon Chemistry Organic chemistry is the study of carbon compounds
Most contain carbon and hydrogen atoms together
Why can carbon atoms form diverse molecules?
Carbon has four valence electrons and may form single, double, triple, or quadruple bonds
Carbon compounds range from simple molecules to complex ones

5. Carbon Chemistry
The bonding versatility of carbon allows it to form many diverse molecules, including carbon skeletons
(a) Methane
(b) Ethane
(c) Ethene (ethylene)
Molecular Formula
Structural Formula
Ball-and-Stick Model
Space-Filling Model H C
CH4
C2H6
C2H4
Name and Comments
Figure 4.3 A-C

6. Carbon Chemistry
The electron configuration of carbon gives it covalent compatibility with many different elements H O N C
Hydrogen
(valence = 1)
Oxygen
(valence = 2)
Nitrogen
(valence = 3)
Carbon
(valence = 4)
Figure 4.4

7. Carbon Chemistry Carbon may bond to itself forming carbon chains
(a) Length
(b) Branching
(c) Double bonds
(d) Rings
Ethane
Propane
Butane
isobutane
1-Butene
2-Butene
Cyclohexane
Benzene
Carbon may bond to itself forming carbon chains
Carbon chains form the skeletons of most organic molecules
Carbon chains vary in length and shape

8. (b) Mammalian adipose cells
Hydrocarbons
Hydrocarbons are molecules consisting of only carbon and hydrogen
Hydrocarbons are found in many of a cell’s organic molecules
(a) A fat molecule
(b) Mammalian adipose cells
100 µm
Fat droplets (stained red)
Figure 4.6 A, B

9. The molecular formula does not necessarily tell you the structural formula…explain.
C4H10
Leading into structural isomers

10. Isomers
Isomers are molecules with the same molecular formula but different structures and properties
Three types of isomers are
Structural
Geometric
Enantiomers

11. Structural Isomers
Molecules with the same molecular formula, but there atoms are connected differently (Different connectivity)
Resulting in different structural formula.
Structure = function, therefore structural isomers function or behave differently

12. AIM: How does carbon lead to the diversity of life?
Chapter 4 – Carbon and the Molecular Diversity of Life
Geometric Isomers
Cis
Trans
Differ in their spatial arrangement about a double bonded carbon
Cis-2-butene
Trans-2-butene

13. Enantiomers Molecules that are mirror images of each other
This can happen only when there is an asymmetric carbon = a carbon with four DIFFERENT groups attached to it.
Asymmetric carbon
mirror

14. Isomers
Thalidomide, an extreme example of isomers behaving differently
The birth defects caused by thalidomide, which was inadvertently taken with R-thalidomide to treat morning sickness symptoms
Conclusion
Just because two molecules have the same molecular formula and may even have the same connectivity, if they can’t be overlaid on top of each other, they aren’t the same.

15. Enantiomers Enantiomers: important in the pharmaceutical industry
L-Dopa
(effective against Parkinson’s disease)
D-Dopa
(biologically inactive)
Figure 4.8

16. Functional Groups
Functional groups are the parts of molecules involved in chemical reactions
They are the chemically reactive groups of atoms within an organic molecule
Give organic molecules distinctive chemical properties
CH3 OH HO O
Estradiol
Testosterone
Female lion
Male lion
Figure 4.9

17. Functional Groups
There are six functional groups that concern us in biology:
Hydroxyl group (-OH)
Carbonyl group (>C=O)
Carboxyl group (-COOH)
Amino group (-NH2)
Sulfhydryl group (-SH)
Phosphate group (-OPO32-)
These functional groups are hydrophilic and increase the solubility of organic compounds in water.

18. Hydroxyl Group
Structure – a hydrogen atom bonded to an oxygen atom which is then bonded to the carbon skeleton of the organic molecule (-OH). (This is not the same thing as an hydroxide ion (OH-)).
Name of Compounds – alcohols (names usually end in –ol).
Example – ethanol – the alcohol found in beer and wine.
Properties:
Polar as a result of the electronegative oxygen drawing electrons toward itself.
Attracts water molecules
Helps dissolve organic compounds such as sugars.

19. Carbonyl Group
Structure – a carbon atom joined to an oxygen atom by a double bond (>C=O).
Name of Compounds:
Ketones – the carbonyl group is within the carbon skeleton.
Aldehydes – the carbonyl group is at the end of the carbon skeleton.
Examples – Acetone, an ketone, and Propanal, an aldehyde.
Properties – a ketone and an aldehyde may be structural isomers, as in the case of acetone and propanal.

20. Carboxyl Group
Structure – an oxygen atom double bonded to a carbon atom that is also bonded to a hydroxyl group (-COOH).
Name of Compounds – Carboxylic acids
Example – Acetic acid
Properties:
Donates H+ and therefore has acidic properties.
Found in ionic form in cells since the H in the hydroxyl portion dissociates readily in water – forms a carboxylate group (-COO-).

21. Amino Group
Structure – a nitrogen atom bonded to two hydrogen atoms and to the carbon skeleton (-NH2).
Name of Compounds – Amines
Example – glycine
Properties:
Can pick up H+ ions and therefore acts as a base.
Ionizes with a charge of +1 in the cell.

22. Sulfhydryl Group Structure – a sulfur atom bonded to a hydrogen atom
(-SH).
Name of Compounds – Thiols.
Example – ethanethiol and cystine (another amino acid)
Properties – two sulfhydryl groups can interact with each other to stabilize large molecules like proteins.

23. Phosphate Group
Structure – a phosphorus atom bonded to four oxygen atoms. One of the oxygen atoms is bonded to the carbon skeleton, two oxygens have a negative charge (-OPO32-).
Name of Compounds – organic phosphates.
Example – glycerol phosphate and adenosine triphosphate.
Properties:
Makes the molecule it is bonded with an anion.
Can transfer energy between organic molecules.

24. Adenosine Triphosphate
1. It is composed of a ribose sugar, three negative phosphates, and an adenine base
2. It’s an RNA nucleotide
3. Primary energy carrying molecule of the cell – fuel for proteins to do work / accelerate matter

25. ATP
When ATP loses one of its phosphate ions to another molecule, such as an enzyme, the enzyme is said to be phosphorylated and possesses more energy.
The remaining molecule is now called adenosine diphosphate (ADP).
The phosphate that is removed from ATP is called an inorganic phosphate and can be shown as Pi

27. Some important functional groups of organic compounds
STRUCTURE
(may be written HO )
HYDROXYL CARBONYL CARBOXYL OH
In a hydroxyl group (—OH), a hydrogen atom is bonded to an oxygen atom, which in turn is bonded to the carbon skeleton of the organic molecule. (Do not confuse this functional group with the hydroxide ion, OH–.)
When an oxygen atom is double-bonded to a carbon atom that is also bonded to a hydroxyl group, the entire assembly of atoms is called a carboxyl group (—COOH). C O
Figure 4.10
The carbonyl group ( CO) consists of a carbon atom joined to an oxygen atom by a double bond. 

28. Some important functional groups of organic compounds
Acetic acid, which gives vinegar its sour tatste
NAME OF COMPOUNDS
Alcohols (their specific names usually end in -ol)
Ketones if the carbonyl group is within a carbon skeleton
Aldehydes if the carbonyl group is at the end of the carbon skeleton
Carboxylic acids, or organic acids
EXAMPLE
Propanal, an aldehyde
Acetone, the simplest ketone
Ethanol, the alcohol present in alcoholic beverages H C OH O
Figure 4.10

29. Some important functional groups of organic compounds
The amino group (—NH2) consists of a nitrogen atom bonded to two hydrogen atoms and to the carbon skeleton.
AMINO SULFHYDRYL PHOSPHATE
(may be written HS )
The sulfhydryl group consists of a sulfur atom bonded to an atom of hydrogen; resembles a hydroxyl group in shape.
In a phosphate group, a phosphorus atom is bonded to four oxygen atoms; one oxygen is bonded to the carbon skeleton; two oxygens carry negative charges; abbreviated P . The phosphate group (—OPO32–) is an ionized form of a phosphoric acid group (—OPO3H2; note the two hydrogens). N H SH O P OH
Figure 4.10