Molecular Biology of the Cell by Bruce Alberts, Alexander Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter Walter by by Bruce Alberts, Alexander Johnson, Julian Lewis, David Morg

100 PANEL 2–6: A Survey of the Nucleotides
BASES
O
NH 2
HC
HC
NH 2
C
C
N
H
N
C
H 3 C
cytosine
O
C
HC
thymine
HC
HC
O
C
T
N
H
C
U
N
H
NH
C
NH
uracil
C
O
O
The bases are nitrogen-containing ring
compounds, either pyrimidines or purines.
5
6
4
1
N
3
N
2
PYRIMIDINE
8
N
7
9
N
5
4
PURINE
6
3
N
1
N
2
adenine
HC
HC
guanine
N
N
H
N
N
H
C
C
C
C
N
O
C
G
N
C
A
C
N
NH
CH
NH 2
PHOSPHATES
The phosphates are normally joined to
the C5 hydroxyl of the ribose or
deoxyribose sugar (designated 5'). Mono-,
di-, and triphosphates are common.
O
– O P O CH2
O –
O O
– O P O P O CH 2
O – O –
O O
– O P O P O
O – O –
as in
AMP
O
as in
ADP
P O CH 2
O –
The phosphate makes a nucleotide
negatively charged.
as in
ATP
NUCLEOTIDES
A nucleotide consists of a nitrogen-containing
base, a five-carbon sugar, and one or more
phosphate groups.
PHOSPHATE
BASE
NH 2
O
– N
O P O CH2
O –
O
H H
H
H
Nucleotides
are the
OH OH
subunits of
SUGAR
the nucleic acids.
N
O
BASIC SUGAR
LINKAGE
N-glycosidic
bond
4
5
3
O
SUGAR
2
BASE
N
C 1
H
The base is linked to
the same carbon (C1)
used in sugar–sugar
bonds.
SUGARS
HOCH 2
O
OH
PENTOSE
a five-carbon sugar
C 5’ O
4’ 1’
3’ 2’
two kinds are used
H
H
OH
H
OH
H
β-D-ribose
used in ribonucleic acid
HOCH 2
O
OH
Each numbered carbon on the sugar of a nucleotide is
followed by a prime mark; therefore, one speaks of the
“5-prime carbon,” etc.
H
H
OH
H
H
H
β-D-2-deoxyribose
used in deoxyribonucleic acid