Download c - Down the Rabbit Hole

Carbon
and the Molecular
Diversity of Life
1
Carbon Chemistry
• Carbon is the Backbone of Biological Molecules
(macromolecules)
• All living organisms Are made up of chemicals
based mostly on the element carbon
2
Organic chemistry
• Biological thought:
• Vitalism (life force outside physical & chemical laws) Berzelius
• Mechanism (all natural phenomena are governed by physical &
chemical laws) Miller
• Carbon unparalleled in its ability to form molecules that are
large, complex and diverse. Why?
3
Organic Chemistry
• Organic chemistry is the study of
carbon compounds
• Carbon atoms can form diverse
molecules by bonding to four other
atoms (tetravalence)
• Carbon compounds range from
simple molecules to complex ones
chains, rings, branched
• Carbon has four valence electrons
and may form single, double, triple,
or quadruple bonds
4
Characteristics of Carbon!
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• The bonding versatility of carbon allows it
to form many diverse molecules, including
carbon skeletons
Name and
Comments
(a) Methane
Molecular Structural
Formula
Formula
Ball-andStick Model
SpaceFilling
Model
H
CH4
H C
H
H
(b) Ethane
H H
C2H6
H C
C H
H H
Figure 4.3 A-C
(c) Ethene
(ethylene)
C2H4
H
H
C C
H
H
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• The electron configuration of carbon gives it
covalent compatibility with many different
elements
Hydrogen
Oxygen
Nitrogen
Carbon
(valence = 1)
(valence = 2)
(valence = 3)
(valence = 4)
H
O
N
C
Figure 4.4
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• Carbon may bond to itself forming carbon chains
• Carbon chains form the skeletons of most organic
molecules
• Carbon chains vary in length and shape
(a) Length
H
H H H H
H C C C C
H H H H
Butane
(b) Branching
(c) Double bonds
(d) Rings
Figure 4.5 A-D
H
H
H
H
H H H
H C C C H
H H H
Propane
H
H C H
H
H
H C C C H
H H H
H H
C C H
H H
Ethane
H H H H
H C C C C
H H
1-Butene
H
H
H
C
C
C H
H
C
C H
C
Cyclohexane
H
isobutane
H
H H H H
H C C C C
H
H
2-Butene
H
H
C C H
C
C
C
H
Benzene
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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
Fat droplets (stained red)
Figure 4.6 A, B
(a) A fat molecule
100 µm
(b) Mammalian adipose cells
9
Isomers
• Isomers are molecules with the same molecular
formula but different structures and properties
• Three types of isomers are
– Structural
H
– Geometric
H C H
H C H
H H H H H
H
H
– Enantiomers
H C C C C C H
H C C C
(a) Structural isomers
H H H
H H H H H
(b) Geometric isomers
X
C
H
X
H
H
X
C
CO2H
(c) Enantiomers
H
C
CH3
Figure 4.7 A-C
C
C
H
X
H
CO2H
NH2 NH2
C
H
CH3
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• Enantiomers Are important in the pharmaceutical
industry
Figure 4.8
L-Dopa
D-Dopa
(effective against
Parkinson’s disease)
(biologically
inactive)
11
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
• There are six functional groups
–
–
–
–
–
–
Hydroxyl
Carbonyl
Carboxyl
Amino
Sulfhydryl
Phosphate
Estradiol
OH
CH3
HO
Female lion
OH
CH3
CH3
O
Figure 4.9
Male lion
Testosterone
12
Functional Groups
FUNCTIONAL
GROUP
HYDROXYL
CARBONYL
CARBOXYL
STRUCTURE
O
O
OH
C
C
OH
(may be written HO
)
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–.)
The carbonyl group
( CO) consists of a
carbon atom joined to
an oxygen atom by a
double bond.

When an oxygen atom is doublebonded to a carbon atom that is
also bonded to a hydroxyl group,
the entire assembly of atoms is
called a carboxyl group (—
COOH).
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Functional Group Examples
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
EXAMPLE
H
H
H
C
C
H
H
H
OH
H
Ethanol, the alcohol
present in alcoholic
beverages
H
O
C
H
Carboxylic acids, or organic acids
H
C
H
C
H
H
Acetone, the simplest ketone
H
H
H
C
C
H
H
C
H
O
C
OH
Acetic acid, which gives vinegar its
sour tatste
O
C
H
Propanal, an aldehyde
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Functional Groups
AMINO
SULFHYDRYL
H
PHOSPHATE
O
N
H
The amino group (—NH2)
consists of a nitrogen atom
bonded to two hydrogen
atoms and to the carbon
skeleton.
O
SH
(may be written HS)
P
OH
OH
In a phosphate group, a phosphorus
The sulfhydryl group consists
atom is bonded to four oxygen
of a sulfur atom bonded to an
atoms; one oxygen is bonded to the
atom of hydrogen; resembles a
carbon skeleton; two oxygens carry
hydroxyl group in shape.
negative charges; abbreviated P .
The phosphate group (—OPO32–) is
an ionized form of a phosphoric acid
group (—OPO3H2; note the two
hydrogens).
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