8. Fig. 4-2
EXPERIMENT
“Atmosphere”
CH4
Water vapor
Electrode
NH
3 H2
Condenser
Cooled water
containing Cold
organic water
molecules
H2 O
“sea”
Sample for
chemical analysis
34. Fig. 4-10a
CHEMICAL
GROUP Hydroxyl Carbonyl Carboxyl
STRUCTURE
(may be written HO—)
In a hydroxyl group (—OH), a The carbonyl group ( CO) When an oxygen atom is
hydrogen atom is bonded to an consists of a carbon atom double-bonded to a carbon
oxygen atom, which in turn is joined to an oxygen atom by a atom that is also bonded to
bonded to the carbon skeleton of double bond. an —OH group, the entire
the organic molecule. (Do not assembly of atoms is called
confuse this functional group a carboxyl group (—COOH).
with the hydroxide ion, OH–.)
NAME OF Alcohols (their specific names Ketones if the carbonyl group is Carboxylic acids, or organic
COMPOUND usually end in -ol) within a carbon skeleton acids
Aldehydes if the carbonyl group
is at the end of the carbon
skeleton
EXAMPLE
Ethanol, the alcohol present in Acetone, the simplest ketone Acetic acid, which gives vinegar
alcoholic beverages its sour taste
Propanal, an aldehyde
FUNCTIONAL Is polar as a result of the A ketone and an aldehyde may Has acidic properties
PROPERTIES electrons spending more time be structural isomers with because the covalent bond
near the electronegative different properties, as is the between oxygen and hydrogen
oxygen atom. case for acetone and propanal. is so polar; for example,
Can form hydrogen bonds with These two groups are also
water molecules, helping found in sugars, giving rise to
dissolve organic compounds two major groups of sugars:
such as sugars.
aldoses (containing an
aldehyde) and ketoses
(containing a ketone). Acetic acid Acetate ion
Found in cells in the ionized
form with a charge of 1– and
called a carboxylate ion (here,
specifically, the acetate ion).
35. Fig. 4-10c
Carboxyl
STRUCTURE NAME OF
Carboxylic acids, or organic COMPOUND
acids
EXAMPLE FUNCTIONAL
Has acidic properties PROPERTIES
because the covalent bond
between oxygen and hydrogen
is so polar; for example,
Acetic acid, which gives vinegar
its sour taste
Acetic acid Acetate ion
Found in cells in the ionized
form with a charge of 1– and
called a carboxylate ion (here,
specifically, the acetate ion).
36. Fig. 4-10d
Amino
STRUCTURE NAME OF
Amines COMPOUND
EXAMPLE FUNCTIONAL
Acts as a base; can PROPERTIES
pick up an H+ from
the surrounding
solution (water, in
living organisms).
Glycine
Because it also has a
carboxyl group, glycine
is both an amine and
a carboxylic acid; (nonionized) (ionized)
compounds with both
groups are called Ionized, with a
amino acids. charge of 1+, under
cellular conditions.
37. Fig. 4-10e
Sulfhydryl
STRUCTURE NAME OF
Thiols COMPOUND
(may be
written HS—)
EXAMPLE FUNCTIONAL
Two sulfhydryl groups PROPERTIES
can react, forming a
covalent bond. This
“cross-linking” helps
stabilize protein
structure.
Cysteine Cross-linking of
cysteines in hair
proteins maintains the
Cysteine is an important
curliness or straightness
sulfur-containing amino
acid. of hair. Straight hair can
be “permanently” curled
by shaping it around
curlers, then breaking
and re-forming the
cross-linking bonds.
38. Fig. 4-10f
Phosphate
STRUCTURE NAME OF
Organic phosphates COMPOUND
EXAMPLE FUNCTIONAL
Contributes negative charge PROPERTIES
to the molecule of which it is
a part (2– when at the end of
a molecule; 1– when located
internally in a chain of
Glycerol phosphate phosphates).
Has the potential to react
In addition to taking part in with water, releasing energy.
many important chemical
reactions in cells, glycerol
phosphate provides the
backbone for phospholipids,
the most prevalent molecules in
cell membranes.
39. Fig. 4-10g
Methyl
STRUCTURE NAME OF
Methylated compounds COMPOUND
EXAMPLE FUNCTIONAL
Addition of a methyl group PROPERTIES
to DNA, or to molecules
bound to DNA, affects
expression of genes.
Arrangement of methyl
groups in male and female
sex hormones affects
5-Methyl cytidine their shape and function.
5-Methyl cytidine is a
component of DNA that has
been modified by addition of
the methyl group.
