Stages of DNA Replication Initiation Elongation Termination
DNA Replication: Mechanism in Replicating the Code and Ensuring Replication Fidelity
Stages of DNA Replication
Initiation
Elongation
Termination
Initiation 1. Initiator proteins binds to the Origin of Replication on the DNA, causing a short section of DNA to unwind. 2. The DNA helicase then unwinds the DNA helices by breaking the pre-existing hydrogen bonds between the deoxynucleotide (dNTP)1. 3. Single-stand binding protein (SSBP), by forming tetramers, binds to the unwinded DNA strands to prevent the DNA strands from rebinding. SSBP also protect the singlestranded nucleotides when exposed during DNA replication and prevent the formation of secondary structures such as hairpin loops that might interfere the replication process. Elongation 4. RNA primase then synthesises a short strand of RNA primer which is complementary to the sequence in DNA template. 5. DNA polymerase III then binds to the RNA primer to elongate/ synthesis/ replicate a complementary daughter strand by adding nucleotide base at the 3' end, reads the template from 5' to 3' direction DNA polymerase III
1
Deoxyribonucleotide / Deoxyribonucleoside triphosphate: substrate for DNA replication, comprises of Adenine (dATP0, Guanine (dGTP), Thymine (dTTP) and Cytosine (dCTP). After binding to the synthesising daughter strand, pyro-phosphate (2 inorganic phosphate ions) are released.
1
© Pei Qin Ng Bachelor of Science (Advanced) - Molecules, Genes and Cells (MGC) 2015
Stages of DNA Replication
Initiation
Elongation
Termination
Initiation 1. Initiator proteins binds to the Origin of Replication on the DNA, causing a short section of DNA to unwind. 2. The DNA helicase then unwinds the DNA helices by breaking the pre-existing hydrogen bonds between the deoxynucleotide (dNTP)1. 3. Single-stand binding protein (SSBP), by forming tetramers, binds to the unwinded DNA strands to prevent the DNA strands from rebinding. SSBP also protect the singlestranded nucleotides when exposed during DNA replication and prevent the formation of secondary structures such as hairpin loops that might interfere the replication process. Elongation 4. RNA primase then synthesises a short strand of RNA primer which is complementary to the sequence in DNA template. 5. DNA polymerase III then binds to the RNA primer to elongate/ synthesis/ replicate a complementary daughter strand by adding nucleotide base at the 3' end, reads the template from 5' to 3' direction DNA polymerase III
1
Deoxyribonucleotide / Deoxyribonucleoside triphosphate: substrate for DNA replication, comprises of Adenine (dATP0, Guanine (dGTP), Thymine (dTTP) and Cytosine (dCTP). After binding to the synthesising daughter strand, pyro-phosphate (2 inorganic phosphate ions) are released.
1
© Pei Qin Ng Bachelor of Science (Advanced) - Molecules, Genes and Cells (MGC) 2015
