Chapter 4
Carbon and the Molecular Diversity of
Life
Ch 4 Carbon and the Molecular Diversity of Life
1.
What is organic chemistry?
-
Branch of chemistry that studies carbon compounds
Ch 4 Carbon and the Molecular Diversity of Life
1.
2.
What is organic chemistry?
What do we know about carbon?
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•
•
•
•
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Atomic # = 6
Forms covalent bonds
Tetravalent – 4 valence electrons – forms 4 bonds
Tetravalence makes large, complex molecules possible.
Determines 3D shape of molecules
Compatible with other abundant elements
Hydrogen
Oxygen
Nitrogen
Carbon
(valence = 1)
(valence = 2)
(valence = 3)
(valence = 4)
H
O
N
C
Ch 4 Carbon and the Molecular Diversity of Life
1.
2.
3.
What is organic chemistry?
What do you know about carbon?
How does carbon contribute to molecular diversity?
•
Carbon skeletons – covalent bonds that link C atoms together
& form the skeletal framework of organic molecules
Figure 4.5 Variations in carbon skeletons
H H
H H H
H C C H
H H
H C C C H
H H H
Ethane
Propane
H H H H
H
H C H
H
H
H C C C C H
H H H H
H C C C H
H H H
(a) Length
(b) Branching
Butane
(c) Double bonds
2-methylpropane
(commonly called isobutane)
H H H H
H H H H
H C C C C H
H H
H C C C C H
H
H
1-Butene
(d) Rings
H
H
H
H
H
H
H
C
C
C H
C
C H
H
C
H
H
Cyclohexane
2-Butene
H
H
C
H
C
C
H CC C H
H
Benzene
Ch 4 Carbon and the Molecular Diversity of Life
1.
2.
3.
4.
What is organic chemistry?
What do you know about carbon?
How does carbon contribute to molecular diversity?
What are hydrocarbons?
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–
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Molecules consisting of only hydrogen & carbon
Fossil fuels
Some are biologically important (fats)
Hydrophobic (non-polar) – oil & water don’t mix
Ch 4 Carbon and the Molecular Diversity of Life
1.
2.
3.
4.
5.
What is organic chemistry?
What do you know about carbon?
How does carbon contribute to molecular diversity?
What are hydrocarbons?
What are isomers?
- compounds w/ the same molecular formula but w/
different structures & therefore, different properties
Figure 4.7 Three types of isomers
H
H C H
H H H
(a) Structural isomers
H C C C C C
H
H
H C C C
H H H
H H H H
X
(b) Geometric isomers
X
H
C C
X
C C
X
H
H
(c) Enantiomers
H C H
H
H
H H
H
CO2H
CO2H
C
C
H
H
NH2 NH2
CH3
L isomer
CH3
D isomer
H
Ch 4 Carbon and the Molecular Diversity of Life
1.
2.
3.
4.
5.
6.
What is organic chemistry?
What do you know about carbon?
How does carbon contribute to molecular diversity?
What are hydrocarbons?
What are isomers?
What are functional groups?
•
Parts of molecules involved in chemical rxns
FUNCTIONAL
GROUP
HYDROXYL
CARBONYL
CARBOXYL
O
OH
O
C
C
OH
STRUCTURE
In a hydroxyl group, a
hydrogen atom is bonded to an
oxygen atom, which in turn is
bonded to the carbon skeleton
of the organic molecule.
COMPOUND
NAME (w/
example)
Alcohol (cholesterol)
 Is polar as a result of the
PROPERTIESelectronegative oxygen atom
drawing electrons toward itself.
 Attracts water molecules; helps
dissolve organic compounds such
as sugars
The carbonyl group
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.
Ketone (fructose)
Aldehyde (ribose)
Carboxylic acid
(lactic acid)
 May be structural isomers
with different properties,
therefore increasing the
reactive diversity of the
carbon chain to which it is
attach.
 Has acidic properties because it is a
source of hydrogen ions. (see below)
H
H
C
H
H
O
H
C
OH
Acetic acid
C
H
O
+ H+
C
O
Acetate ion
AMINO
SULFHYDRYL
H
PHOSPHATE
FUNCTIONAL
GROUP
SH
N
H
The amino group consists
of a nitrogen atom bonded
to two hydrogen atoms
and to the carbon skeleton.
Amine (histamine)
Thiol (cysteine)
 Acts as a base; can pick
up a proton from the
surrounding solution. (see
below)
H
N
The sulfhydryl group
consists of a sulfur atom
bonded to an atom of
hydrogen.
 Two sulfhydryl groups
can interact to help
stabilize protein
structure.
H
+N
H
H
H
***AMINO ACID = carbon
chain with both a carboxyl
group AND an amino group***
STRUCTURE
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.
COMPOUND
Organic phosphate
NAME (w/
(ATP)
example)
 Makes the molecule of which
it is a part an anion (negatively
charged ion). Can transfer
energy between organic
molecules.
FUNCTIONAL
PROPERTIES