DNA复制(DNA Replication)英文版

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Initiation of DNA Replication
Elongation of DNA Replication Finishing of DNA Replication
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The Concepts of DNA Replication
●DNA replication is a process in which two same copies can be obtained.
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Special Constructure of DNA During Replication
Okazaki fragment In DNA discontinuous reproduction, it's the DNA fragments synthetized using the lagging strand template.Then they are covalent connected to a ssDNA. Its length is different in prokaryote and eukaryote.
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Elongation of DNA Replication
After RNA primer is synthetized later, the elongation of DNA
begins. The leading chain is continuously synthetized, and the lagging chain is discontinuously synthetized.In the replication fork, DNA helicase moves from 5' to 3' on the DNA template . DNA primase periodically bonds with helicase, and synthetizes new primer in the lagging chain template . Afteran Okazaki fragment is completely synthetized,the core which is responsible for the Okazaki fragment, slides from the sliding clamp and DNA.
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Enzyme and Protein Involved in Replication ●DNA polymerase; ●DNA helicase; ●Singlestrand DNA binding protein （SSB）; ●DNA topoisomerase; ●DNA ligase; ●Initiator;
●In E.coli，Dna A bonds 9bp reverse repeat sequences,
and degenerates 13bpsequences.Then open initiation complex is formed.
●In the condition that ATP offer energy,13bpare unlinked.
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DNA Ligase Nicks occur in the deve-loping molecule becau-se the RNA primer is removed and synthesis proceeds in a discontinuous manner on the lagging strand. The final replicationproduct does not have any nicks bec-ause DNA ligase forms a covalent phosphodiester bond between 3'hydroxyl and 5'phosphate groups.
and continues to synthetze leading chain
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Initiation of DNA Replication
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Elongation of DNA Replication
The Constructure of Elongation DNA Replication
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SSB
It In te grats w i th ssDNA unlinked by DNA helicase in replication fork,to prevent ssDNA rematching and to protect it from degradating by protein or nucleic acid enzymes.
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Elongation of DNA Replication
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Elongation of DNA Replication
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origin
initiation of replication occur,are required for DNAreplication initiation. It's sequence are rich in AT , usually is a cross structure
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• Wuhan University • The College of Life Science
静思笃行 持中秉正
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Contents
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The Concepts of DNA Replication Materials And Special Constructure of DNA Enzyme and Protein Involved in Replication
●DNA replication is semi-conservative, one strand serves as the template for the second strand. ● Furthermore, DNA replication only occurs at a specific step in the cell cycle.
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Special Constructure of DNA During Replication
The entire set of cis-acting DNA sequences that is
sufficient to direct the initiation of DNA replication
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DNA helicase
In discontinuous reproduction of DNA, it integrats in front of replication fork, catalyzing double chains of DNA to unlink. And it has the activity of ATPase, so two kinds of activivity coupling, by using the activity of ATPase as the energy to unlink two chains.
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Initiator
A protein specifically recognizes a DNA element in the rep licator and activates the initiation of replication.
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Initiation of DNA Replication
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Special Constructure of DNA During Replication
Replicon
As a unit for replication a DNA sequence.It contains a replicationorigin, some times it also contains a finishing sequence.
At that time all ssDNAare covered by SSB.
●Dna B unlinks dsDNA template in replication fork.
Primase catalysizes to synthetize primers.
●Core I adds dNTP to 3'-OH on leading chain template
Replicator
Distinction between the replicator and origin of replication
-------Origin of replication is always a part of the
replicator.
The specific sites at which DNA unwinding and
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Enzyme and Protein Involved in Replication
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DNA polymerase
It is the enzyme using one of strand of dsDNA as a template to synthetize new DNA . It has two domains that's, palm domain, t humb d omain a n d fingers domain. It has three activity, 3'-5' and 5'-3' exonuclease activity;DNA polymerase.
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Enzyme and Protein Involved in Replication
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DNA topoisomerase
This enzyme catalyzes the formation of negative supercoils that is thought to aid with the unwinding process.
Protokaryotic replicon
Eukaryotic replicon
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Special Constructure of DNA During Replication Replication Fork
It's the Y shape area formed by dsDNA which is being replicated.Unwinded two single templateDNA and the new chains which is being synthetized consist ofthe head of Y , and dsDNA template constitutes the tail of Y.
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Materials
●Template:One of the strand of dsDNA;
● dNTPs:4 kinbs of deoxynucleotide triphosphates, that's,ATP,GTP,CTP,TTP;
● Primer:usually RNA; ● Proteins and enzyme:such as DNA polymerase,DNA helicase,Singlestrand DNA binding protein （SSB）,DNA topoisomerase,DNA ligase,Telomerase (special in euka-ryotes);