Biology Reference
In-Depth Information
DNA (contains genes)
Transcription (RNA synthesis)
mRNA (copy of gene)
Translation (protein synthesis)
Protein (cellular machinery)
FIGURE 11-1.
Information flow in a typical cell. Genes are sections of DNA that are transcribed into mRNA, which
then goes to the ribosomes to guide the assembly of proteins.
NH
2
NH
2
N
N
N
CH
N
O
N
N
O
O
O
O
O
O
−
−
O
P
O
P
O
P
O
CH
2
O
P
O
P
O
P
O
CH
2
O
O
O
−
O
−
O
−
O
−
O
−
O
−
H
H
H
H
H
H
H
H
HO
H
HO
H
Deoxyadenosine 5
-triphosphate
(dATP)
Deoxycytidine 5
-triphosphate
(dCTP)
O
O
CH
3
N
HN
HN
CH
N
N
H
2
N
N
O
O
O
O
O
O
O
−
−
O
P
O
P
O
P
O
CH
2
O
P
O
P
O
P
O
CH
2
O
O
O
−
O
−
O
−
O
−
O
−
O
−
H
H
H
H
H
H
H
H
HO
H
HO
H
Deoxyguanosine 5
-triphosphate
(dGTP)
Deoxythymidine 5
-triphosphate
(dTTP)
FIGURE 11-2.
Structures of the four deoxynucleotides. Observe that two sections of each molecule shown—the
phosphates (P- and O-containing groups) and the deoxyribose sugars (the pentagonal structures
with O at the apex)—are identical. Only the nitrogenous bases (the one- or two-membered N-
containing rings) differ.
genes on or off. They are responsible for cell structure, cell movement,
and cell reproduction. They are also, as we shall see, responsible
for circadian rhythms. In eukaryotic cells, the genes for all proteins
(including the circadian timing proteins) are found in the nucleus.
