1. By: Laken Poole

2. DNA Replication occurs before a cell splits apart. The replication process takes place during mitosis. To be more specific, it takes place in a step of mitosis called interphase. Interphase has different steps also. DNA replication takes place during the S phase of interphase. 3. DNA replication is a process that is very essential in every cell. If DNA replication did not occur, cells wouldnt function properly. DNA replication occurs so that when cells divide, the new cells have the same DNA as the cell they were made from. 4. As you know, DNA is made up of two strands. During DNA replication, an enzyme called DNA helicase unzips these two strands. These two strands have different names, which are the lagging and leading strand. 5. The leading strand is synthesized continuously in the 5 prime to 3 prime direction, while the lagging strand is synthesized discontinuously in the 5 prime to 3 prime direction. 6. DNA polymerase III adds nucleotides to the end of a growing DNA strand. DNA primase is an enzyme that marks a starting point on the lagging strand. DNA polymerase I removes the starting point from the lagging strand and replaces it with DNA. 7. DNA ligase joins Okazaki fragments, which are short, newly synthesized DNA fragments that are formed on the lagging strand. DNA ligase also seals repairs, and seals recombination fragments. That is how DNA replication occurs. 8. So you can get a better understanding, the following slides will demonstrate the entire DNA replication process. 9. Helicase 10. 5A TTHelicaseAC CAATCGGCTAGCATCGGC3GT3G= Phosphate = Sugar = Adenine = Thymine = Cytosine = Guanine DNA replication begins when the enzyme helicase unwinds and breaks the bonds between the nucleotides of the DNA molecule.5 11. A5TCG GTTCGGCTAGCATCGGC= AdenineAA3= Phosphate = SugarAHelicaseC3T= Thymine = Cytosine = Guanine5 12. A5T= Phosphate = SugarACGHelicaseCG= AdenineAT AGGCTAGCATCGGC= ThymineTC33T= Cytosine = Guanine5 13. A53TT CGCGTHelicase AAGCATCGGC= ThymineCTAGG= AdenineTC3= Phosphate = SugarA= Cytosine = Guanine5 14. A53TT CGCGHelicaseT= AdenineA= ThymineTA CGGCTAGCATC3= Phosphate = SugarAGGC= Cytosine = Guanine5 15. A53TT CGCGTAAHelicase CAGCATCGGC= ThymineTCT= AdenineGG3= Phosphate = SugarA= Cytosine = Guanine5 16. A53TT CGCGTAATHelicase= Adenine = ThymineGC GAGCATCGGC= CytosineCT3= Phosphate = SugarA= Guanine5 17. A53TT CGCGTAATC GHelicase= Adenine = ThymineG= CytosineC TCATCGGC= GuanineAG3= Phosphate = SugarA5 18. A53TT CGCGTAATG= Adenine = ThymineGCHelicase T= CytosineC= GuanineA GCATC3= Phosphate = SugarAGGC5 19. A53TT CGCGTAAT= Adenine = ThymineGC G= CytosineC THelicase G A= GuanineAC TC3= Phosphate = SugarAGGC5 20. A53TT CGCGTAAT= Adenine = ThymineGC G= CytosineCHelicaseT G= GuanineAC ATC3= Phosphate = SugarAG GC5 21. 3ATT5A= Phosphate = SugarGC CGTAA= Adenine = ThymineT= CytosineGC GC TG AHelicaseC TC3= GuanineAGGC5 22. 3ATT5A= Phosphate = SugarGC CGTAA= Adenine = ThymineT= CytosineGC GC TGCATC3= GuanineAGHelicaseG C5 23. TTGCGTAATCGG T= Phosphate = Sugar = Adenine = Thymine = CytosineC= GuanineAGCATC33AC5AGGC5 24. TTGCGTAATCGG T= Phosphate = Sugar = Adenine = Thymine = CytosineC= GuanineAGTCGGCNow there are two complimentary strands of DNA.CA33AC5A5 25. DNAA 5 T Polymerase III C C T AT RNA Primer 3 A G DNA polymerase III is able to add nucleotides continuously to the leading strand of DNA. Meanwhile, the lagging strand goes through many different steps to add the nucleotides.C G T GG A TRNA G RNA Primer Primase CLeading StrandLagging StrandA CA C3T GGC5 26. TT5AADNA C Polymerase C T III A C G T3TRNA Primer 3 A5GAs shown, RNA primase adds an RNA primer to the lagging strand.G A TGRNA Primer RNA C A PrimaseG ATC3CGGC5 27. TT5A3ADNA C Polymerase C T III A C G TT RNA Primer 3 A G5As shown, RNA primase adds an RNA primer to the lagging strand.G A TG C RNA Primer AG ATC3CGGCRN Prim5 28. 3RNA Primer TTTAAC5AGGC DNA T Polymerase A III C G TG5A TNow, the RNA primase is gone and the next enzyme takes over.GRNA Primer C AGCATC33GGC5 29. 3RNA Primer TTTAAC5AGGGGCT DNA A Polymerase C III G TA5 Now, the RNA primase is gone and the next enzyme takes over.TD RNA Primer C Polym GAGCATC33GGC5 30. 3RNA Primer TTTAAC5AGGGGAAC TA DNA Polymerase C G III TT5Now, the RNA primase is gone and the next enzyme takes over.DN RNA Primer C Polym GAGCATC33GGC5 31. TTRNA Primer T3AC5AGCA The next enzyme is DNA polymerase I.GG GTAAATTCDNA G Polymerase T5G DNA RNA Primer C Polymerase AIGCATC33GGC5 32. TTGCThis enzyme converts the RNA into DNA and synthesizes the lagging strand in the 5 to 3 direction.GTAATCGA G G A T5CATC33DNA G RNA Primer C Polymerase I AG T DNA G PolymeraseRNA Primer T3AC5AGGC5 33. TTGCThis enzyme converts the RNA into DNA and synthesizes the lagging strand in the 5 to 3 direction.GTAATCGGCT DNA G Polymerase A IIIRNA Primer T3AC5AA G G ADNA T Polymerase G RNAI Primer C A C5TC33GGC5 34. RNA Primer T3TTAAC5AGGCGT ATCCTADNA G Polymerase A III C3DNA G A Polymerase I TGG5AGC33GRNA Primer C A5This enzyme converts the RNA into DNA and synthesizes the lagging strand in the 5 to 3 direction.C T G C5 35. TTRNA Primer T3AC5AGC3AG5DNA G G Polymerase I ATAATATCGCGGCTAG3CA DNA C Polymerase G 3 III5RNA Primer CThis enzyme converts the RNA into DNA and synthesizes the lagging strand in the 5 to 3 direction.A C T G C5 36. TT3AC5AGC5GRNA Primer T 3 DNA A G Polymerase I GTATAATATCGCGGCTAGCATC DNA G 3 Polymerase3RNA Primer C AThis enzyme converts the RNA into DNA and synthesizes the lagging strand in the 5 to 3 direction.5C T G C5 37. TTAC5AGCG53DNA polymerase I has synthesized as far as it could. Now its time for the next enzymeRNA Primer T Polymerase 3 I A CGCGTAATCGT ATCGGCTAGCCATTC3AGGG DNA3RNA Primer C A5C5 38. 5ATTAC3GC5DNA polymerase I has synthesized as far as it could. Now its time for the next enzymePolymerase RNA Primer A T 3 I A T GCGTAATCGCGT ATCGGCTAGCCATTC3AGGG DNAC3RNA Primer C A5C5 39. 5ATTGC5DNA polymerase I has synthesized as far as it could. Now its time for the next enzymeRNA I T Primer AGTCGCGTAATGTAATCGGCTAGCCATTC33ACAC3GGG DNAC3RNA Primer C A5C5 40. 5ATTGC5DNA polymerase I has synthesized as far as it could. Now its time for the next enzymeGTCGCGTAATGTAATCGGCTAGCCATTC33ACAC3RNA I T Primer AGGG DNAC3RNA Primer C A5C5 41. 5ATTGCGTTCCTAGCATCGDNA polymerase I has synthesized as far as it could. Now its time for the next enzymeGG3AA5G DNAC35* Note: The short segment of DNA that was just created is called an Okazaki Fragment.ATTACGCGTAATCAC3G3RNA Primer C A C T G C5 42. 5AT35ATWhich isTATACGCGGCGTATAATATCGCGGCTAGCCATTCGGGCC333RNA Primer C A5C5 43. 5AT35ATWhich isTATACGCGGCGTATAATATCGCGGCTAGCCATTCGGGCC333RNA Primer C A5C5 44. 5AT35ATWhich isTATACGCGGCGTATAATATCGCGGCTAGCCATTCGGGCC3Ligas 53RNA Primer C A5C5 45. 5AT35ATWhich isTATACGCGGCGTATAATATCGCGGCTAGCCATTCGGGCC3DNA 5 Ligase3RNA Primer C A5C5 46. 5AT35DNA Ligase!!!!ATTDNA A LigaseTACGCGGCGTATAATATCGCGGCTAGCCATTCGGGCC333RNA Primer C A5C5 47. TTC5AC35ATATDNA A LigaseGCGCGTAATCGGNow, DNA ligase forms a phosphodiester bond.T ATCGGCTAGCCATTC3AGGGC33RNA Primer C A5C5 48. 35TTACGCGCGTATAATATCGCGGCTAGCCATTC5AGGGCC3Once it does that, it leaves.3A TT3A DNA Ligase GRNA Primer C A5C5 49. ATTAC35TTAGCG DNAGCGTATAATATCGCGGCTAGCCATTC5AGGGCC3Once it does that, it leaves.33LigaseRNA Primer C A5C5 50. ATTAC35TTAGCGGCGTATAATATCGCGGCTAGCCATTC5AGGGCC3Once it does that, it leaves.33DNA LigasRNA Primer C A5C5 51. ATTAC35TTAGCGGCGTATAATATCGCGGCTAGCCATTC5AGGGCC3Once it does that, it leaves.33DNA LigasRNA Primer C A5C5 52. ATTAC35TTAGCGGCGTATAATATCGCGGCTAGCCATTC5AGGGCC3Once it does that, it leaves.33D LigRNA Primer C A5C5 53. ATTAC35TTAGCGGCGTATAATATCGCGGCTAGCCATTC5AGGGCC3Once it does that, it leaves.33RNA Primer C A5C5 54. TT3 Now, the 5 nextAC5AGCGTTACGCenzyme, which we had already seen beforeAGTTAATATCGCGGCTAGCCATTC3AGGGC33RNA Primer C A5C3 55. TTC5AC53ATATAGCGCGIs????GTTAATATCGCGGCTAGCCATTC3AGGGC33RNA Primer C A5CR 3 56. TTC5AC53ATATAGCGCGIs????GTTAATATCGCGGCTAGCCATTC3AGGGC33RNA Primer C A5CRNA 3 57. TTC5AC53ATATAGCGCGIs????GTTAATATCGCGGCTAGCCATTC3AGGC33RNA Primer C ARNA 3 Primase C G5 58. TTG35AC5ACGTT Yep RNA primase. The cycle that had just happened, begins again!AACGCGTAT ATATCGCGGCTAGCCATTC3AGGC33RNA Primer C A5RNA G Primase 3 C 59. TTC5AC35ATATAGCGCGTAATCGGRemember, RNA primase adds an RNA primer to the lagging strand.T ATCGGCTAGCCATTC3AGGC33RNA Primer C A5RNA G Primase C5 60. TTC5AC35ATATAGCGCGTAATCGGRemember, RNA primase adds an RNA primer to the lagging strand.T ATCGGCTAGCCATTC3AGGC33RNA Primer C A5RNA G RNA Primer 5 Primase C 61. TT5A35AC CG GTT The RNA primase leaves, once again.AACGCGTTAATATCGCGGCTAGCCATTC3AGGC33RNA Primer C A5RNA G RNA Primase 3 Primer C 62. TT5A35AC CG GTT The RNA primase leaves, once again.AACGCGTTAATATCGCGGCTAGCCATTC3AGGGC33RNA Primer C A5RNA RNA Primer 3 C 63. TT5A35AC CG GTT The RNA primase leaves, once again.AACGCGTTAATATCGCGGCTAGCCATTC3AGGGC33RNA Primer C A5RNA Primer R 3 C 64. ATT53ATTACGGCGTATAATATCGCGGCTAGCCATTC5AGGGCC C3GLeaving us to the next enzyme.33RNA Primer C A5RNA Primer 3 C 65. ATTAC3G5TTACGGCGTATAATATCGCGGCTAGCCATTC5AGGGCC3Do you remember what that is?33RNA Primer C A5RNA Primer 3 C 66. ATTAC3G5TTACGGCGTATAATATCGCGGCTAGCCATTC5AGGGCC3Do you remember what that is?33RNA Primer C A5RNA Primer 3 C Po 67. ATTAC35TTAGCGGCGTATAATATCGCGGCTAGCCATTC5AGGCD RNA Primer 3 C PolyC3Did you guess yet?33RNA Primer C AG5 68. ATTACG53TTACGGCGTATAATATCGCGGCTAGCCATTC5AGGCC3Do you remember?33RNA Primer C A5DNA G Polymer RNA Primer 3 C 69. ATTC35TATAGCGGCGTATAATATCGCGGCTAGCATC5AGGCC33 Did you get it right? DNA polymerase I is back again to synthesize this part of the DNA strand.53RNA Primer C A CT DNA G Polymerase RNA Primer 3 I C 70. TT5AAC CG GAdding corresponding nucleotides to the strand.ACGC5TT3AGTTAATATCGCGGCTAGCATC3AGGC3RNA Primer C A C5DNA T Polymerase G RNA Primer 5 I C 3 71. TT5AAC CG GAdding corresponding nucleotides to the strand.ACGC5TT3AGTTAATATCGCGGCTAGCATC3AGGC3RNA Primer C A5DNA C Polymerase T I G RNA Primer 5 3 C 72. TT5AAC CG GGCAdding corresponding nucleotides to the strand.AC5TT3AGTTAATATCGCGGCTAGCATC3AGGC3RNA Primer C DNA A Polymerase C I T C53G GRNA Primer 5 C 73. TT5AAC CG GGCAdding corresponding nucleotides to the strand.AC5TT3AGTTAATATCGCGGCTAGCATATC3AGCGGC3DNA C RNA Primer G Polymerase A G I C53RNA Primer 5 C G 74. TTC5ACATATAGCGGCGTAAT53And replacing the RNA with DNA.T ATCGGCTAGCGCATATC3AGCGGC3DNA G RNA Primer G C Polymerase T I A C53RNA Primer 5 C G 75. TTC5ACATATAGCGCGTATAG53 And replacing the RNA with DNA.T ATCGGCTAGCGCATATC3AGCGGC35DNA T A Polymerase G C RNA Primer G I C3RNA Primer 5 C G 76. TTC5ACATATAGCGGCGTATAATCGGAnd then its leaves again after finishing its job..AG5CT3TTACGCATATC3AGCGGC353DNA G C Polymerase G C IRNA Primer 5 C G 77. TTAC5AGCG5And then its leaves again after finishing its job..TT3AACGCGTA TT ATACGCGCTAGCGCATATC3AGCGGC3Meanwhile G T53DNA Polymer C A I GRNA Primer 5 C G 78. TTC5AC TATATAGCGGCGATAAT35DNA ligase returns yet again to form another phosphodiester bond.A CGGCTAGCGTATCGCGGCDN LigaCA3T3C G T53DNA Polymer C A I GRNA Primer 5 C G 79. ATTCTATAGCGGCGTATAATATCGCGDNA D LigasGCGCPolymTATAGCGCATATC5AGCGGCC335DNA ligase returns yet again to form another phosphodiester bond.533RNA Primer 5 C G 80. ATTCTATAGCGGCGTATAATATCGCGGCTAG5AC35DNA ligase returns yet again to form another phosphodiester bond.GD PolymDNA C LigaseTACGCATATC33GCGGC53RNA Primer 5 C G 81. ATTCTATAGCGGCGTATAATATCGGCTAGCGATATC5AGCGGCC335DNA ligase returns yet again to form another phosphodiester bond.533DNA G G Ligase CCTDN A Polym C IRNA Primer 5 C G 82. TTC5ACATATAGCGGCGTAAT35Remember, DNA polymerase I has the job of replacing RNA with DNA.T ATCGGCTAGCGATAC3AGCGCDNA G G LigaseCCT533DNA C Polyme T I AGRNA Primer 5 C G 83. TTC5ACATATAGCGCGTA T53 While the DNA ligase leaves.GT ATACGCGCGTAGCATC3AGGCT3G DNA Ligase C ADNA Polymeras T A C G I RNA Primer 5 C G G53C 84. TTC5ACATATAGCGCGTAATG35The DNA polymerase I is replacing the RNA with DNA.T ATCGCGGCGC DNATATLigase AGCGCATC3AGGC3T DNA C G Polymerase RNA Primer 5 G IC A53 85. ATTCTATAGCGGCGTATAATATCGCGGCGCTATAGCGCATATC5AGCGCC335533DNA LigasDNA G Polymerase 5 C G 86. ATTCTATAGCGGCGTATAATATCGCGGCGCTATAGCGCATATC5AGCGCC335533LDNA G Polymerase 5 C G 87. TTC5AC TATATAGCGGCGATAAT35Then it leaves after the job is done.A CGCGGCGCTATAGCGCATATC3TGCGC353GDNA 5 C Polyme G 88. TTC5ACATATAGCGGCGTAAT35T ATCGCGGCGCTATAGCGCATATC3AGCGGCGC3Then it leaves after the job is done.535D 89. TTC5ACATATAGCGGCGTAATCGGCTA35T ATCGGCTAGCGCATATC3AGCGGCGC3The DNA ligase has yet one last bond to form!53D Lig5 90. TTC5ACATATAGCGGCGTAAT35The DNA ligase has yet one last bond to form!T ATCGCGGCGCTATAGCGCATATC3AGCGGCGC353DN Liga 5 91. ATTCTATAGCGGCGTATAA5ATATCGGCTAC35The DNA ligase has yet one last bond to form!C GCTAGCGCATATC3GGCGGCGC353DNA Ligase 5 92. ATTCTATAGCGGCGTATAA5ATATCGGCTAC35The DNA ligase has yet one last bond to form!C GCTAGCGCATATC3GGCGC353GG DNA Ligase C5 93. ATTACG3 The DNA 5Tligase has yet one last bond to form!TACGGCGTATAATATCGCGGCGCTATAGCGCATATC5AGCGCC353GG DNA Ligase C35 94. TTC5ACATATAGCGCGTA53 As it finishes its last jobGT ATATCGCGGCGCTATAGCGCATATC3AGCGC353DNA G GLigase C5 95. ATTACGTTACGGCGTATAATATCGCGGCGCTATAGCGCATATC5AGCGCC353 As it finishes its last job53DNA G GLigase C35 96. TTC5ACATATAGCGCG53 Then it leaves again.GTTAATATCGCGGCGCTATAGCGCATATC3AGC3GGC53GDNAC5 97. TTC5ACATATAGCGCG53 Then it leaves again.GTTAATATCGCGGCGCTATAGCGCATATC3AGCGGCGC353DNA5 98. TTC5ACATATAGCGCG53 Then it leaves again.GTTAATATCGCGGCGCTATAGCGCATATC3AGCGGCGC3535 99. TTC5ACATATAGCGCG53 Then it leaves again.GTTAATATCGCGGCGCTATAGCGCATATC3AGCGGCGC3535 100. TTAC5AGCG35Now we are left with two identical strands of DNA.ATTACGCGTTAATATCGCGGCGCTATAGCGCATATC3AGCGGCGC3535 101. Keep in mind that the DNA molecules are in a twisted shape. 102. Like this 103. So really we are left with this. 104. What would happen if a mistake were made during the replication process??? 105. Sometimes, during DNA replication, nucleotide bases are incorrectly paired. 106. Naturally, during DNA replication, the mistakes are fixed. 107. Sometimes, however, the mistakes cannot be fixed and they become mutations. 108. They become permanent mutations after the next cell division. This is because once these mistakes have been established, the cell no longer recognizes them as errors. 109. Special Vocabulary: Telomeres- Telomeres are structures found at the end of chromosomes. Okazaki fragments- Okazaki fragments are short, newly formed DNA segments. DNA ligase- DNA ligase forms a phosphodiester bond, joining the Okazaki fragments into a continuous strand of DNA. 110. Special Vocabulary: Telomerase- Telomerase is an enzyme that is especially found in cancer cells. This enzyme adds nucleotides to telomeres. Cancer- Cancer is a disorder when some of the bodys cells lose the ability to control growth. Transplanted cells- Transplanted cells are injected into your body to replace damaged or diseased cells. 111. Special Vocabulary: Cloning- Cloning is making genetically identical cells that were produced from a single cell. Aging- Aging is the process of growing older. 112. THATS THE END OF THE DNA REPLICATION PROCESS 113. Thanks for watching!!!