7. Living S cells
(control)
Living R cells
(control)
Heat-killed
S cells
(control)
Mixture of
heat-killed
S cells and
living R cells
Mouse dies Mouse diesMouse healthy Mouse healthy
Living S cells
EXPERIMENT
RESULTS
Figure 16.2
19. Figure 16.7
3.4 nm
1 nm
0.34 nm
Hydrogen bond
(a) Key features of
DNA structure
Space-filling
model
(c)(b) Partial chemical structure
3′ end
5′ end
3′ end
5′ end
T
T
A
A
G
G
C
C
C
C
C
C
C
C
C
C
C
G
G
G
G
G
G
G
G
G
T
T
T
T
T
T
A
A
A
A
A
A
27. Figure 16.9-3
(a) Parent molecule (b) Separation of
strands
(c)“Daughter” DNA molecules,
each consisting of one
parental strand and one
new strand
A
A
A
A
A
A
A
A
A
A
A
A
T
T
T
T
T
T
T
T
T
T
T
T
C
C
C
C
C
C
C
C
G
G
G
G
G
G
G
G
31. Figure 16.11
Bacteria
cultured in
medium with
15
N (heavy
isotope)
Bacteria
transferred to
medium with
14
N (lighter
isotope)
DNA sample
centrifuged
after first
replication
DNA sample
centrifuged
after second
replication
Less
dense
More
dense
Predictions: First replication Second replication
Conservative
model
Semiconservative
model
Dispersive
model
21
3 4
EXPERIMENT
RESULTS
CONCLUSION
33. Figure 16.12
(a) Origin of replication in an E. coli cell (b) Origins of replication in a eukaryotic cell
Origin of
replication
Parental (template) strand
Double-
stranded
DNA molecule
Daughter (new)
strand
Replication
fork
Replication
bubble
Two daughter
DNA molecules
Origin of replication
Double-stranded
DNA molecule
Parental (template)
strand
Daughter (new)
strand
Bubble Replication fork
Two daughter DNA molecules
0.5µm
0.25µm
39. Figure 16.14
New strand Template strand
Sugar
Phosphate Base
Nucleoside
triphosphate
DNA
polymerase
Pyrophosphate
5′
5′
5′
5′
3′
3′
3′
3′
OH
OH
OH
P P i
2 P i
P
P
P
A
A
A
A
T T
T
T
C
C
C
C
C
C
G
G
G
G
41. Figure 16.15
Leading
strand
Lagging
strand
Overview
Origin of replication Lagging
strand
Leading
strand
Primer
Overall directions
of replication
Origin of
replication
RNA primer
Sliding clamp
DNA pol III
Parental DNA
3′
5′
5′
3′
3′
5′
3′
5′
3′
5′
3′
5′
43. Figure 16.16a
Origin of replication
Overview
Leading
strand
Leading
strand
Lagging
strand
Lagging strand
Overall directions
of replication
1
2
44. LE 16-15_6
5′
3′
Primase joins RNA
nucleotides into a primer.
Template
strand
5′ 3′
Overall direction of replication
RNA primer
3′
5′
3′
5′
DNA pol III adds
DNA nucleotides to
the primer, forming
an Okazaki fragment.
Okazaki
fragment
3′
5′
5′
3′
After reaching the
next RNA primer (not
shown), DNA pol III
falls off.
3′
3′
5′
5′
After the second fragment is
primed, DNA pol III adds DNA
nucleotides until it reaches the
first primer and falls off.
3′
3′
5′
5′
DNA pol I replaces
the RNA with DNA,
adding to the 3′ end
of fragment 2.
3′
3′
5′
5′
DNA ligase forms a
bond between the newest
DNA and the adjacent DNA
of fragment 1.
The lagging
strand in the region
is now complete.
45. Figure 16.17
Overview
Leading
strand
Origin of
replication Lagging
strand
Leading
strandLagging
strand Overall directions
of replicationLeading strand
DNA pol III
DNA pol III Lagging strand
DNA pol I DNA ligase
Primer
Primase
Parental
DNA
5′
5′
5′
5′
5′
3′
3′
3′
3′
3′3 2 1
4
47. Figure 16.18
Parental DNA
DNA pol III
Leading strand
Connecting
protein
Helicase
Lagging strandDNA
pol III
Lagging
strand
template
5′
5′
5′
5′
5′
5′
3′ 3′
3′
3′
3′
3′
52. LE 16-18
End of parental
DNA strands
5′
3′
Lagging strand 5′
3′
Last fragment
RNA primer
Leading strand
Lagging strand
Previous fragment
Primer removed but
cannot be replaced
with DNA because
no 3′ end available
for DNA polymerase
5′
3′
Removal of primers and
replacement with DNA
where a 3′ end is available
Second round
of replication
5′
3′
5′
3′
Further rounds
of replication
New leading strand
New leading strand
Shorter and shorter
daughter molecules
58. Figure 16.22a
DNA double helix
(2 nm in diameter)
DNA, the double helix
Nucleosome
(10 nm in diameter)
Histones
Histones
Histone
tail
H1
Nucleosomes, or “beads on
a string” (10-nm fiber)