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Chapter 4. Carbon and the Molecular Diversity of Life. Figure 4.1. Carbon Chemistry. Carbon is the backbone of biological m olecules (macromolecules) All living organisms are made up of chemicals based mostly on the element carbon. Carbon Chemistry. - PowerPoint PPT Presentation
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1
Chapter 4Carbon 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
Carbon Chemistry• Organic chemistry is the study of
carbon compounds• Carbon atoms can form diverse molecules
by bonding to four other atoms• Carbon compounds range from simple
molecules to complex ones• Carbon has four valence electrons and
may form single, double, or triple.
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• 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
HH
HH
HH
H
HH
H
H HHH
C
C C
C C
CH4
C2H6
C2H4
Name and Comments
Figure 4.3 A-C
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• The electron configuration of carbon gives it covalent compatibility with many different elements
H O N C
Hydrogen(bonds = 1)
Oxygen(bonds = 2)
Nitrogen(bonds = 3)
Carbon(bonds = 4)
Figure 4.4
6
• Carbon may bond to itself forming carbon chains
• Carbon chains form the skeletons of most organic molecules
• Carbon chains vary in length and shape
HHH
HH
H H H
HH
H
H H H
H H HH H
H
H
H
H
H
H
HH
HH H H H
H HH H
H H H H
H H
H HHHHH H
HH
C C C C C
C C C C C C C
CCCCCCCC
C
CC
CC
C
CCC
CCC
H
H
H
HHH
H
(a) Length
(b) Branching
(c) Double bonds
(d) Rings
Ethane Propane
n-Butane isobutane
1-Butene 2-Butene
Cyclohexane Benzene
H H H HH
Figure 4.5 A-D
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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 cells100 µm
Fat droplets (stained red)
Figure 4.6 A, B
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Isomers• Isomers are molecules with the same
molecular formula but different structures and properties
• Three types of isomers are– Structural– Geometric– Enantiomers
H H H H HH
H H H H HH
HHH
HH
H
H
H
H
HHH
H
H
H
H
CO2H
CH3
NH2C
CO2H
HCH3
NH2
X XX
X
C C C C C
CC
C C C
C C C C
C
(a) Structural isomers
(b) Geometric isomers
(c) Enantiomers
H
Figure 4.7 A-C
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• Enantiomers Are important in the pharmaceutical industry
L-Dopa(effective against Parkinson’s disease)
D-Dopa(biologically inactive)Figure 4.8
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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
• They give organic molecules distinctive chemical properties
CH3OH
HO
O
CH3
CH3OH
Estradiol
Testosterone
Female lion
Male lionFigure 4.9
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• Seven functional groups are important in the chemistry of life– Hydroxyl– Carboxyl– Amino– Phosphate– Carbonyl– Methyl– Sulfhydryl
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Some important functional groups of organic compounds
FUNCTIONALGROUP
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).
CO O
COH
Figure 4.10
The carbonyl group ( CO) consists of a carbon atom joined to an oxygen atom by a double bond.
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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
HH
H
H H
C C OHH
H
H
HH
H
HC C H
C
C C
C C C
O
H OH
O
H
HH H
H O
HFigure 4.10