mechanism of dna replication?
prabhasdarling:
i need clear explanation of each step note: shud b simple to learn quick
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Mechanisms of DNA replications are:
1.Activation of Deoxyribonucleotides: They occur freely in the nucleoplasm.They are of four types-deAMP,deGMP,deCMP and deTMP.
2.Exposure of DNA strands:Enzyme helicase acts and opens the two strands of DNA . The whole strands however does not opens at one stretch but the point of separation proceeds slowly towards the direction hence giving it a Y-shaped structure called replication fork.
3.RNA Primer: It is essential for the formation of new DNA chains.
4.DNA Polymerases: Prokaryotes have three major types of DNA synthesizing enzymes called DNA Polymerases III, II and I. All of them add nucleotides in 5'-->3' direction on 3-->5 strand.
5.Base Pairing: The two separated DNA strands in the replication fork function as templates. Deoxyriboribonucleoside triphosphates come to lie opposite the nitrogen bases of exposed DNA templates.
6.Chain Formation: It requires DNA Polymerase III in prokaryotes and Polymeraseδ/ε in eukaryotes.
7.Proof Reading and DNA repair: A wrong base is sometimes introduced during replication. The frequency is one in ten thousand. DNA Polymerase III is able to sense the same. It goes back, removes the wrong base, allows addition to proper base and proceeds forward.
1.Activation of Deoxyribonucleotides: They occur freely in the nucleoplasm.They are of four types-deAMP,deGMP,deCMP and deTMP.
2.Exposure of DNA strands:Enzyme helicase acts and opens the two strands of DNA . The whole strands however does not opens at one stretch but the point of separation proceeds slowly towards the direction hence giving it a Y-shaped structure called replication fork.
3.RNA Primer: It is essential for the formation of new DNA chains.
4.DNA Polymerases: Prokaryotes have three major types of DNA synthesizing enzymes called DNA Polymerases III, II and I. All of them add nucleotides in 5'-->3' direction on 3-->5 strand.
5.Base Pairing: The two separated DNA strands in the replication fork function as templates. Deoxyriboribonucleoside triphosphates come to lie opposite the nitrogen bases of exposed DNA templates.
6.Chain Formation: It requires DNA Polymerase III in prokaryotes and Polymeraseδ/ε in eukaryotes.
7.Proof Reading and DNA repair: A wrong base is sometimes introduced during replication. The frequency is one in ten thousand. DNA Polymerase III is able to sense the same. It goes back, removes the wrong base, allows addition to proper base and proceeds forward.
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DNA replication is a fundamental part of the life cycle of all organisms. Not surprisingly many aspects of this process display profound conservation across organisms in all domains of life. The chapters in this volume outline and review the current state of knowledge on several key aspects of the DNA replication process. This is a critical process in both normal growth and development and in relation to a broad variety of pathological conditions including cancer. The reader will be provided with new insights into the initiation, regulation, and progression of DNA replication as well as a collection of thought provoking questions and summaries to direct future investigations.
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