Welcome Each of
You to My
Molecular Biology
Class
Molecular Biology of the Gene,
5/E --- Watson et al,(2004)
Part I,Chemistry and Genetics
Part II,Maintenance of the Genome
Part III,Expression of the Genome
Part IV,Regulation
Part V,Methods
3/15/05
Part II,Maintenance of the Genome
Dedicated to the structure of
DNA and the processes that
propagate,maintain and alter it
from one cell generation to the
next
Ch 6,The structures of DNA and RNA
Ch 7,Chromosomes,chromatins and
the nucleosome
Ch 8,The replication of DNA
Ch 9,The mutability and repair of
DNA
Ch 10,Homologous recombination at
the molecular level
Ch 11,Site-specific recombination
and transposition of DNA
3/15/05
CHAPTER 8,The replication
of DNA
?Molecular Biology Course
Teaching Arrangement
? Watch animation-Understand
replication
? Go through structural tutorial-
Experience the BEAUTY of the
nature
? QA-comprehensive understanding
of Chapter 8
? Summary and highlight Key points
CHAPTER 8 The replication of DNA
The Chemistry of DNA Synthesis
? The Mechanism of DNA Polymerase
? The Replication Fork
? The Specialization of DNA
Polymerases
? DNA Synthesis at the Replication Fork
? Initiation of DNA Replication
? Binding and Unwinding
? Finishing Replication
General
Detailed
CHAPTER 8 The replication of DNA
The first part describes
the basic chemistry of
DNA synthesis and the
function of the DNA
polymerase
CHAPTER 8 The replication of DNA
The Chemistry of DNA
CHAPTER 8 The replication of DNA
? DNA synthesis requires
deoxynucleoside triphosphates and
a primer:template junction
? DNA is synthesized by extending
the 3’ end of the primer
? Hydrolysis of pyrophosphate (PPi) is
the driving force for DNA synthesis
3/18/05
Figure 8-3 Substrate required for DNA synthesis
The mechanism of DNA
Polymerase (Pol)
CHAPTER 8 The replication of DNA
3/18/05
DNA Pol use a single active site to
catalyze DNA synthesis
A single site to catalyze the addition
of any of the four dNTPs,
Recognition of different dNTP by
monitoring the ability of incoming
dNTP in forming A-T and G-C base
pairs; incorrect base pair dramatically
lowers the rate of catalysis (kinetic
selectivity).
3/18/05
Th
e me
ch
an
ism
of
D
NA
P
ol
Figure 8-3
Distinguish between rNTP and dNTP
by steric exclusion of rNTPs from
the active site.
3/18/05
Th
e me
ch
an
ism
of
D
NA
P
ol
Figure 8-4
DNA Pol resemble a hand that grips
the primer-template junction The
me
ch
an
ism
of
D
NA
P
ol
Figure 8-5
Schematic drawing
T7 DNA pol
Figure 8-8
Thumb
Fingers
Palm
Catalytic sites for addition and
removal of dNTPs,
Binds to two metal ions that alter
the chemical environment around
the catalytic site,(how?)
3/18/05
DNA Polymerase-palm domain***
Binds to the incoming dNTP,
encloses the correct paired dNTP
to the position for catalysis
Bends the template to expose the
only nucleotide at the template
that ready for forming base pair
with the incoming nucleotide
Stabilization of the pyrophosphate
DNA Polymerase-finger domain
Not directly involved in catalysis
Interacts with the synthesized DNA
to maintain correct position of the
primer and the active site,and to
maintain a strong association
between DNA Pol and its
substrate.
3/18/05
DNA Polymerase-thumb domain
DNA Pol are processive enzymes T
he
me
ch
an
ism
of
D
NA
P
ol
Processivity is a characteristic of
enzymes that operate on polymeric
substrates.
The processivity of DNA Pol is the
average number of nucleotides added
each time the enzyme binds a
primer:template junction (a
few~50,000),
The rate of DNA synthesis is closely
related to the polymerase
processivity,because the rate-
limiting step is the initial binding
of polymerase to the primer-
template junction.
Figure 8-9
Exonucleases proofread newly
synthesized DNA The
me
ch
an
ism
of
D
NA
P
ol
The occasional flicking of the bases into
“wrong” tautomeric form results in
incorrect base pair and mis-
incorporation of dNTP,(10-5 mistake)
The mismatched dNMP is removed by
proofreading exonuclease,a part of
the DNA polymerase.
How does the exonucleases work? Kinetic
selectivity
Figure 8-10
The second part describes
how the synthesis of DNA
occurs in the context of an
intact chromosome at
replication forks,An array of
proteins are required to
prepare DNA replication at
these sites,
CHAPTER 8 The replication of DNA
The replication fork
CHAPTER 8 The replication of DNA
? The junction between the newly
separated template strands and the
unreplicated duplex DNA
3/18/05
Both strands of DNA are synthesized
together at the replication fork.The
re
pli
ca
tio
n
fo
rk
Figure 8-11
Leading strand
Lagging strand
Okazaki fragment
Replication fork
The initiation of a new strand of DNA
require an RNA primerThe
re
pli
ca
tio
n
fo
rk
? Primase is a specialized RNA
polymerase dedicated to making
short RNA primers on an ssDNA
template,Do not require specific
DNA sequence.
? DNA Pol can extend both RNA and
DNA primers annealed to DNA
template
RNA primers must be removed to
complete DNA replicationThe
re
pli
ca
tio
n
fo
rk
A joint efforts of
RNase H,DNA
polymerase &
DNA ligase
Figure 8-12
Th
e r
ep
lic
ati
on
fo
rk
Figure 8-15
Topoisomerase removes supercoils
produced by DNA unwinding at the
replication fork
DNA helicases unwind the double
helix in advance of the replication
fork
Th
e r
ep
lic
ati
on
fo
rk Hexameric protein (see your CD)
Figure 8-13
Single-stranded binding proteins
(SSBs) stabilize single-stranded
DNA
Th
e r
ep
lic
ati
on
fo
rk
? Cooperative binding
? Sequence-independent manner
(electrostatic interactions)
Figure 8-14
Th
e r
ep
lic
ati
on
fo
rk
DNA helicase,SSB,primase,DNA
topoisomerase
Replication fork enzymes extend the
range of DNA polymerase substrate
DNA Pol can not accomplish
replication without the help of
other enzymes
The specialization of DNA
polymerases
CHAPTER 8 The replication of DNA
3/18/05
DNA Pols are specialized for
different roles in the cellThe
sp
ec
ial
iza
tio
n
of
D
NA
po
l
? Each organism has a distinct set of
different DNA Pols
? Different organisms have different
DNA Pols
DNA Pol III holoenzyme,a protein
complex responsible for E,coli
genome replication
DNA Pol I,removes RNA primers in E,
coli
? Polymerase switching,the process
of replacing DNA Pola/primase with
DNA Pold or DNA Pole,
Table 8-2
Sliding clamps dramatically increase
DNA polymerase activityThe
sp
ec
ial
iza
tio
n
of
D
NA
po
l
? Encircle the newly synthesized
double-stranded DNA and the
polymerase associated with the
primer:template junction
? Ensures the rapid rebinding of DNA
Pol to the same primer:template
junction,and thus increases the
processivity of Pol.
? Eukaryotic sliding DNA clamp is PCNA
Figure 8-17
Figure 8-19 Sliding DNA clamps are
found across all organism and share
a similar structure
Sliding clamps are opened and
placed on DNA by clamp loadersThe
sp
ec
ial
iza
tio
n
of
D
NA
po
l
? Clamp loader is a special class of
protein complex catalyzes the
opening and placement of sliding
clamps on the DNA,such a process
occurs anytime a primer-template
junction is present.
? Sliding clamps are only removed from
the DNA once all the associated
enzymes complete their function.
DNA synthesis at the replication
fork
CHAPTER 8 The replication of DNA
3/18/05
? At the replication,the leading strand
and lagging strand are synthesized
simultaneously,The biological
relevance is listed in P205-206
? To coordinate the replication of both
strands,multiple DNA Pols function
at the replication fork,DNA Pol III
holoenzyme is such an example.
Figure 8-20 The composition of the
DNA Pol III holoenzyme
Figure 8-21*** Trombone model
Interactions between replication fork
proteins form the E,coli replisome
DN
A
sy
nt
he
sis
at
th
e r
ep
lic
ati
on
fo
rk
Replisome is established by protein-protein
interactions
1,DNA helicase & DNA Pol III holoenzyme,
which is mediated by the clamp loader and
stimulates the activity of the helicase (10-
fold)
2,DNA helicase & primase,which is
relatively week and strongly stimulates the
primase function (1000-fold),This
interaction is important for regulation the
length of Okazaki fragments.
DNA Pol III holoenzyme,helicase and
primase interact with each other to
form replisome,a finely tuned factory
for DNA synthesis with the activity of
each protein is highly coordinated.
The third part focuses on the
initiation and termination of
DNA replication,Note that
DNA replication is tightly
controlled in all cells and
initiation is the step for
regulation,
CHAPTER 8 The replication of DNA
Initiation of DNA replication
CHAPTER 8 The replication of DNA
3/18/05
Specific genomic DNA
sequences direct the initiation of
DNA replication
3/18/05
Origins of replication,the sites
at which DNA unwinding and
initiation of replication occur,
Ini
tia
tio
n
of
D
NA
re
pli
ca
tio
n
The replicon model of
replication initiation
3/18/05
? Proposed by Jacob and Brenner
in 1963
? All the DNA replicated from a
particular origin is a replicon
? Two components,replicator and
initiator,control the initiation of
replication
Ini
tia
tio
n
of
D
NA
re
pli
ca
tio
n
Replicator,the entire
site of cis-acting DNA
sequences sufficient
to direct the initiation
of DNA replication
Initiator protein,
specifically recognizes
a DNA element in the
replicator and
activates the initiation
of replication
Figure 8-23
Replicator sequences include
initiator binding sites and easily
unwound DNA
3/18/05
Ini
tia
tio
n
of
D
NA
re
pli
ca
tio
n
Binding and Unwinding,origin
selection and activation by the
initiator protein
CHAPTER 8 The replication of DNA
3/18/05
? Three different functions of
initiator protein,(1) binds to
replicator,(2) distorts/unwinds a
region of DNA,(3) interacts with
and recruits additional replication
factors
? DnaA in E,coli (all 3 functions),
origin recognition complex (ORC)
in eukaryotes (functions 1 & 3)
Protein-protein and protein-DNA
interactions direct the initiation
process
3/18/05
Bi
nd
ing
an
d u
nw
ind
ing
? DnaA recruits the DNA helicase
DnaB and the helicase loader DnaC
? DnaB interacts with primase to
initiate RNA primer synthesis,see
replisome part for more details.
Figure 8-26*
Eukaryotic chromosome are
replicated exactly once per cell
cycle,which is critical for these
organims
3/18/05
Bi
nd
ing
an
d u
nw
ind
ing
Pre-replicative complex (pre-RC)
formation directs the initiation of
replication in eukaryotes
Bi
nd
ing
an
d u
nw
ind
ing
Initiation in eukaryotes requires
two distinct steps
? Replicator selection,the
process of identifying
sequences for replication
initiation (G1 phase),which is
mediated by the formation of
pre-RCs at the replicator
region,
Figure 8-29
pre-RC
formation
Origin activation,pre-RCs are
activated by two protein
kinases (Cdk and Ddk) that
are active only when the cells
enter S phase.
Figure 8-30 pre-RC activation
& assembly of the replication
fork in eukaryotes
Pre-RC formation and activation
is regulated to allow only a
single round of replication
during each cell cycle.
Bi
nd
ing
an
d u
nw
ind
ing
Only one opportunity for pre-RCs to
form,and only one opportunity for
pre-RC activation.
Figure 8-31 Effect of Cdk activity on
pre-RC formation and activation
Figure 8-32 Cell cycle regulation of
Cdk activity and pre-RC formatin
Finishing replication
CHAPTER 8 The replication of DNA
3/18/05
Type II topoisomerases are required to
separate daughter DNA molecules
Fin
ish
ing
re
pli
ca
tio
n
Lagging strand synthesis is unable to
copy the extreme ends of the linear
chromosome
Fin
ish
ing
re
pli
ca
tio
n
The End replication problem
(Figure 8-34)
Telomerase is a novel DNA
polymerase that does not require an
exogenous template
Fin
ish
ing
re
pli
ca
tio
n
How telomerase works? (Figure
8-36
How the end problem is
eventually resolved? (Figure 8-
37)
T1:The Chemistry of DNA Synthesis
T2,The Mechanism of DNA Polymerase
T3,The Replication Fork （分）
T4,The Specialization of DNA
Polymerases （分）
T5,DNA Synthesis at the Replication
Fork （合）
T6,Initiation of DNA Replication
T7,Binding and Unwinding
T8,Finishing Replication
CHAPTER 8 The replication of DNA
重点
CHAPTER 8 The replication of DNA
3/18/05
Completely understand 三个 Animations
1,DNA polymerization (Topics 1 & 2)
2,DNA replication (Topics 3－ 5)
3,Action of Telomerase (Topic 8)
Topic 6-7,Initiation of DNA replication,
重点掌握 (1) 概念 origin of replication,
replicator,initiator (DnaA & ORC),以及
图 8－ 23,25,26; （ 2） How the
eukaryotic chromosomes are ensured
to replicate exactly once per cell cycle?
Complete all the
excises on your study
CD,Enjoy it
Homework
You to My
Molecular Biology
Class
Molecular Biology of the Gene,
5/E --- Watson et al,(2004)
Part I,Chemistry and Genetics
Part II,Maintenance of the Genome
Part III,Expression of the Genome
Part IV,Regulation
Part V,Methods
3/15/05
Part II,Maintenance of the Genome
Dedicated to the structure of
DNA and the processes that
propagate,maintain and alter it
from one cell generation to the
next
Ch 6,The structures of DNA and RNA
Ch 7,Chromosomes,chromatins and
the nucleosome
Ch 8,The replication of DNA
Ch 9,The mutability and repair of
DNA
Ch 10,Homologous recombination at
the molecular level
Ch 11,Site-specific recombination
and transposition of DNA
3/15/05
CHAPTER 8,The replication
of DNA
?Molecular Biology Course
Teaching Arrangement
? Watch animation-Understand
replication
? Go through structural tutorial-
Experience the BEAUTY of the
nature
? QA-comprehensive understanding
of Chapter 8
? Summary and highlight Key points
CHAPTER 8 The replication of DNA
The Chemistry of DNA Synthesis
? The Mechanism of DNA Polymerase
? The Replication Fork
? The Specialization of DNA
Polymerases
? DNA Synthesis at the Replication Fork
? Initiation of DNA Replication
? Binding and Unwinding
? Finishing Replication
General
Detailed
CHAPTER 8 The replication of DNA
The first part describes
the basic chemistry of
DNA synthesis and the
function of the DNA
polymerase
CHAPTER 8 The replication of DNA
The Chemistry of DNA
CHAPTER 8 The replication of DNA
? DNA synthesis requires
deoxynucleoside triphosphates and
a primer:template junction
? DNA is synthesized by extending
the 3’ end of the primer
? Hydrolysis of pyrophosphate (PPi) is
the driving force for DNA synthesis
3/18/05
Figure 8-3 Substrate required for DNA synthesis
The mechanism of DNA
Polymerase (Pol)
CHAPTER 8 The replication of DNA
3/18/05
DNA Pol use a single active site to
catalyze DNA synthesis
A single site to catalyze the addition
of any of the four dNTPs,
Recognition of different dNTP by
monitoring the ability of incoming
dNTP in forming A-T and G-C base
pairs; incorrect base pair dramatically
lowers the rate of catalysis (kinetic
selectivity).
3/18/05
Th
e me
ch
an
ism
of
D
NA
P
ol
Figure 8-3
Distinguish between rNTP and dNTP
by steric exclusion of rNTPs from
the active site.
3/18/05
Th
e me
ch
an
ism
of
D
NA
P
ol
Figure 8-4
DNA Pol resemble a hand that grips
the primer-template junction The
me
ch
an
ism
of
D
NA
P
ol
Figure 8-5
Schematic drawing
T7 DNA pol
Figure 8-8
Thumb
Fingers
Palm
Catalytic sites for addition and
removal of dNTPs,
Binds to two metal ions that alter
the chemical environment around
the catalytic site,(how?)
3/18/05
DNA Polymerase-palm domain***
Binds to the incoming dNTP,
encloses the correct paired dNTP
to the position for catalysis
Bends the template to expose the
only nucleotide at the template
that ready for forming base pair
with the incoming nucleotide
Stabilization of the pyrophosphate
DNA Polymerase-finger domain
Not directly involved in catalysis
Interacts with the synthesized DNA
to maintain correct position of the
primer and the active site,and to
maintain a strong association
between DNA Pol and its
substrate.
3/18/05
DNA Polymerase-thumb domain
DNA Pol are processive enzymes T
he
me
ch
an
ism
of
D
NA
P
ol
Processivity is a characteristic of
enzymes that operate on polymeric
substrates.
The processivity of DNA Pol is the
average number of nucleotides added
each time the enzyme binds a
primer:template junction (a
few~50,000),
The rate of DNA synthesis is closely
related to the polymerase
processivity,because the rate-
limiting step is the initial binding
of polymerase to the primer-
template junction.
Figure 8-9
Exonucleases proofread newly
synthesized DNA The
me
ch
an
ism
of
D
NA
P
ol
The occasional flicking of the bases into
“wrong” tautomeric form results in
incorrect base pair and mis-
incorporation of dNTP,(10-5 mistake)
The mismatched dNMP is removed by
proofreading exonuclease,a part of
the DNA polymerase.
How does the exonucleases work? Kinetic
selectivity
Figure 8-10
The second part describes
how the synthesis of DNA
occurs in the context of an
intact chromosome at
replication forks,An array of
proteins are required to
prepare DNA replication at
these sites,
CHAPTER 8 The replication of DNA
The replication fork
CHAPTER 8 The replication of DNA
? The junction between the newly
separated template strands and the
unreplicated duplex DNA
3/18/05
Both strands of DNA are synthesized
together at the replication fork.The
re
pli
ca
tio
n
fo
rk
Figure 8-11
Leading strand
Lagging strand
Okazaki fragment
Replication fork
The initiation of a new strand of DNA
require an RNA primerThe
re
pli
ca
tio
n
fo
rk
? Primase is a specialized RNA
polymerase dedicated to making
short RNA primers on an ssDNA
template,Do not require specific
DNA sequence.
? DNA Pol can extend both RNA and
DNA primers annealed to DNA
template
RNA primers must be removed to
complete DNA replicationThe
re
pli
ca
tio
n
fo
rk
A joint efforts of
RNase H,DNA
polymerase &
DNA ligase
Figure 8-12
Th
e r
ep
lic
ati
on
fo
rk
Figure 8-15
Topoisomerase removes supercoils
produced by DNA unwinding at the
replication fork
DNA helicases unwind the double
helix in advance of the replication
fork
Th
e r
ep
lic
ati
on
fo
rk Hexameric protein (see your CD)
Figure 8-13
Single-stranded binding proteins
(SSBs) stabilize single-stranded
DNA
Th
e r
ep
lic
ati
on
fo
rk
? Cooperative binding
? Sequence-independent manner
(electrostatic interactions)
Figure 8-14
Th
e r
ep
lic
ati
on
fo
rk
DNA helicase,SSB,primase,DNA
topoisomerase
Replication fork enzymes extend the
range of DNA polymerase substrate
DNA Pol can not accomplish
replication without the help of
other enzymes
The specialization of DNA
polymerases
CHAPTER 8 The replication of DNA
3/18/05
DNA Pols are specialized for
different roles in the cellThe
sp
ec
ial
iza
tio
n
of
D
NA
po
l
? Each organism has a distinct set of
different DNA Pols
? Different organisms have different
DNA Pols
DNA Pol III holoenzyme,a protein
complex responsible for E,coli
genome replication
DNA Pol I,removes RNA primers in E,
coli
? Polymerase switching,the process
of replacing DNA Pola/primase with
DNA Pold or DNA Pole,
Table 8-2
Sliding clamps dramatically increase
DNA polymerase activityThe
sp
ec
ial
iza
tio
n
of
D
NA
po
l
? Encircle the newly synthesized
double-stranded DNA and the
polymerase associated with the
primer:template junction
? Ensures the rapid rebinding of DNA
Pol to the same primer:template
junction,and thus increases the
processivity of Pol.
? Eukaryotic sliding DNA clamp is PCNA
Figure 8-17
Figure 8-19 Sliding DNA clamps are
found across all organism and share
a similar structure
Sliding clamps are opened and
placed on DNA by clamp loadersThe
sp
ec
ial
iza
tio
n
of
D
NA
po
l
? Clamp loader is a special class of
protein complex catalyzes the
opening and placement of sliding
clamps on the DNA,such a process
occurs anytime a primer-template
junction is present.
? Sliding clamps are only removed from
the DNA once all the associated
enzymes complete their function.
DNA synthesis at the replication
fork
CHAPTER 8 The replication of DNA
3/18/05
? At the replication,the leading strand
and lagging strand are synthesized
simultaneously,The biological
relevance is listed in P205-206
? To coordinate the replication of both
strands,multiple DNA Pols function
at the replication fork,DNA Pol III
holoenzyme is such an example.
Figure 8-20 The composition of the
DNA Pol III holoenzyme
Figure 8-21*** Trombone model
Interactions between replication fork
proteins form the E,coli replisome
DN
A
sy
nt
he
sis
at
th
e r
ep
lic
ati
on
fo
rk
Replisome is established by protein-protein
interactions
1,DNA helicase & DNA Pol III holoenzyme,
which is mediated by the clamp loader and
stimulates the activity of the helicase (10-
fold)
2,DNA helicase & primase,which is
relatively week and strongly stimulates the
primase function (1000-fold),This
interaction is important for regulation the
length of Okazaki fragments.
DNA Pol III holoenzyme,helicase and
primase interact with each other to
form replisome,a finely tuned factory
for DNA synthesis with the activity of
each protein is highly coordinated.
The third part focuses on the
initiation and termination of
DNA replication,Note that
DNA replication is tightly
controlled in all cells and
initiation is the step for
regulation,
CHAPTER 8 The replication of DNA
Initiation of DNA replication
CHAPTER 8 The replication of DNA
3/18/05
Specific genomic DNA
sequences direct the initiation of
DNA replication
3/18/05
Origins of replication,the sites
at which DNA unwinding and
initiation of replication occur,
Ini
tia
tio
n
of
D
NA
re
pli
ca
tio
n
The replicon model of
replication initiation
3/18/05
? Proposed by Jacob and Brenner
in 1963
? All the DNA replicated from a
particular origin is a replicon
? Two components,replicator and
initiator,control the initiation of
replication
Ini
tia
tio
n
of
D
NA
re
pli
ca
tio
n
Replicator,the entire
site of cis-acting DNA
sequences sufficient
to direct the initiation
of DNA replication
Initiator protein,
specifically recognizes
a DNA element in the
replicator and
activates the initiation
of replication
Figure 8-23
Replicator sequences include
initiator binding sites and easily
unwound DNA
3/18/05
Ini
tia
tio
n
of
D
NA
re
pli
ca
tio
n
Binding and Unwinding,origin
selection and activation by the
initiator protein
CHAPTER 8 The replication of DNA
3/18/05
? Three different functions of
initiator protein,(1) binds to
replicator,(2) distorts/unwinds a
region of DNA,(3) interacts with
and recruits additional replication
factors
? DnaA in E,coli (all 3 functions),
origin recognition complex (ORC)
in eukaryotes (functions 1 & 3)
Protein-protein and protein-DNA
interactions direct the initiation
process
3/18/05
Bi
nd
ing
an
d u
nw
ind
ing
? DnaA recruits the DNA helicase
DnaB and the helicase loader DnaC
? DnaB interacts with primase to
initiate RNA primer synthesis,see
replisome part for more details.
Figure 8-26*
Eukaryotic chromosome are
replicated exactly once per cell
cycle,which is critical for these
organims
3/18/05
Bi
nd
ing
an
d u
nw
ind
ing
Pre-replicative complex (pre-RC)
formation directs the initiation of
replication in eukaryotes
Bi
nd
ing
an
d u
nw
ind
ing
Initiation in eukaryotes requires
two distinct steps
? Replicator selection,the
process of identifying
sequences for replication
initiation (G1 phase),which is
mediated by the formation of
pre-RCs at the replicator
region,
Figure 8-29
pre-RC
formation
Origin activation,pre-RCs are
activated by two protein
kinases (Cdk and Ddk) that
are active only when the cells
enter S phase.
Figure 8-30 pre-RC activation
& assembly of the replication
fork in eukaryotes
Pre-RC formation and activation
is regulated to allow only a
single round of replication
during each cell cycle.
Bi
nd
ing
an
d u
nw
ind
ing
Only one opportunity for pre-RCs to
form,and only one opportunity for
pre-RC activation.
Figure 8-31 Effect of Cdk activity on
pre-RC formation and activation
Figure 8-32 Cell cycle regulation of
Cdk activity and pre-RC formatin
Finishing replication
CHAPTER 8 The replication of DNA
3/18/05
Type II topoisomerases are required to
separate daughter DNA molecules
Fin
ish
ing
re
pli
ca
tio
n
Lagging strand synthesis is unable to
copy the extreme ends of the linear
chromosome
Fin
ish
ing
re
pli
ca
tio
n
The End replication problem
(Figure 8-34)
Telomerase is a novel DNA
polymerase that does not require an
exogenous template
Fin
ish
ing
re
pli
ca
tio
n
How telomerase works? (Figure
8-36
How the end problem is
eventually resolved? (Figure 8-
37)
T1:The Chemistry of DNA Synthesis
T2,The Mechanism of DNA Polymerase
T3,The Replication Fork （分）
T4,The Specialization of DNA
Polymerases （分）
T5,DNA Synthesis at the Replication
Fork （合）
T6,Initiation of DNA Replication
T7,Binding and Unwinding
T8,Finishing Replication
CHAPTER 8 The replication of DNA
重点
CHAPTER 8 The replication of DNA
3/18/05
Completely understand 三个 Animations
1,DNA polymerization (Topics 1 & 2)
2,DNA replication (Topics 3－ 5)
3,Action of Telomerase (Topic 8)
Topic 6-7,Initiation of DNA replication,
重点掌握 (1) 概念 origin of replication,
replicator,initiator (DnaA & ORC),以及
图 8－ 23,25,26; （ 2） How the
eukaryotic chromosomes are ensured
to replicate exactly once per cell cycle?
Complete all the
excises on your study
CD,Enjoy it
Homework
