DNA replication Central dogma of molecular biology

DNA replication

Central dogma of molecular

biology

1.the basic principle of DNA

replication

(1) Semiconservative

replication

a. concept

b. evidence

c. conclusion

(2) Semidiscontinuous replication

* The synthesis direction of

DNA polymerase

* leading strand & lagging

strand

* Okazaki fragment

(3) RNA primer

* the synthesis

* the function

(4) fidelity

2. Enzymes & proteins cooperate

in the DNA replication

(1) E.coli DNA polymerase I

(Kornberg enzyme,DNA-Directed

DNA polymerase,DDDP,pol I )

* The principle materials for pol I

# four dNTP

# Mg 2+

# RNA primer or DNA single

strand possessed 3’-OH

# DNA template

* Multiple function of pol I

Klenow fragment-------

(large fragment)

DNA polymerase activity,

3’-5’ exonuclease activitysmall fragment-------

5’-3’ exonuclease activity

5’ 3’ 3’ 5’ exonuclease exonuclease DNA polymerase activity activity activity

Small fragment large fragment (Klenow fragment)

pol I

Proofreading

* the principle materials for pol II

& pol III

# four dNTP

# Mg 2+

# RNA primer or DNA single

strand possessed 3’-OH

# DNA template

* the characteristics of pol II & pol III

pol II---mostly concerned with

proofreading & DNA repair

pol III---- indispensable for DNA

replication,the highest rate

of chain elongation and

processive

(2) DNA polymerase in eukaryocyte polymerase : gap filling & synthesis of lagging

strand

: DNA proofreading & repair

: DNA repair

: mitochondria DNA synthesis

: processive,leading strand synthesis,

need the assistance of PCNA

(3) helicase & gyrase

a. helicase

* function

* require

b. single strand binding protein

(SSB) ,helix disabling

protein,HDP

* function

c. topoisomerase I

* function

d. topoisomerase II, gyrase

* function

(4) Primosome

(5) DNA ligase

* function

* require

* process

* characteristics

* usage

3.procedure of DNA replication

(1) the initiation of the

replication

* the origin of replication ----

The special structure

(ori C)

* the process of initiation

formation of replication fork

( replication bubbles)

* how to deal with synthesis

direct ?

(3) the termination of the

replication

(2) the elongation of the

replication

*Removes primers---- pol I

small fragment

* fills the gap with dNTP----- pol I

large fragment

(Klenow fragment)

* ligation----DNAligase

4. Summarize of DNA replication

a.identification of the origin of

replication

b.unwinding (denature)of ds DNA to

provide ssDNA

c. formation of replication fork

d.initiation of DNA synthesis & elongation

e. formation of replication bubbles with

ligation of the newly synthesized DNA

segment

f. Reconstitution of chromatin DNA

5.Telomere & telomerase

(1) telomere

*concept

*structure

* function

(2) The function & molecular

components of telomerase

* function

* components (RNP)

* mechanism

• Telomerase & carcinoma

5.DNA damage & repair

(1) the basic of repair

(2)the causes of DNA damage

*remove purine by heat &

acid

• ionizing radiation

• ultraviolet ray

• chemical agents

(3) The type of DNA damage

(4)Mechanism of DNA repair

* photo repair

* excision repair

significant (correct large defects)

* base excision repair

a.process

• Characteristics

• summarize

a. the enzyme uracil DNA

glycosylase removes the uracil

created by spontaneous

deamination of cytosine

b. an endonuclease cuts the

backbone near the defect

c. an endonuclease removes a

few bases

d. the defect is filled in by the

action of a repair polymerase

( pol I )

e. The strand is rejoined

by ligase