DNA Model

1. DNA Replication By: Laura Keller

2. DNA • The DNA double helix refers to the shape of the DNA molecule, or the twisted ladder. It has two intertwining strands made of sugar and phosphate with links across the middle. The rungs of the ladder are base pairs made of four different bases, represented by the letters A, T, G, and C.

3. 5’ 3’ The Enzyme DNA helicase “unzips” or unwinds the double stranded DNA at the origin of replication by breaking hydrogen bonds between complementary strands. Key = Phosphate = Sugar = Adenine = Thymine = Guanine Hydrogen Bond 3’ 5’ = Cytosine

4. DNA Helicase Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

9. Key DNA Helicase = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

10. Key = Phosphate DNA Helicase = Sugar = Adenine = Thymine = Guanine = Cytosine

11. Key = Phosphate = Sugar DNA Helicase = Adenine = Thymine = Guanine = Cytosine

12. Key = Phosphate = Sugar = Adenine DNA Helicase = Thymine = Guanine = Cytosine

13. Key = Phosphate = Sugar = Adenine = Thymine Helicase = Guanine = Cytosine

14. Key = Phosphate = Sugar = Adenine = Thymine licase = Guanine = Cytosine

15. Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

16. Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

17. Lagging Strand Leading Strand Then, on the leading strand, DNA Polymerase III adds the 5’ phosphate end of a free floating nucleotide to the exposed 3’ OH ends on the single stranded DNA in a continuous fashion. The leading strand elongates toward the replication fork. Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

18. DNA Polymerase III Lagging Strand Leading Strand Then, on the leading strand, DNA Polymerase III adds the 5’ phosphate end of a free floating nucleotide to the exposed 3’ OH ends on the single stranded DNA in a continuous fashion. The leading strand elongates toward the replication fork. Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

23. Then, on the leading strand, DNA Polymerase III adds the 5’ phosphate end of a free floating nucleotide to the exposed 3’ OH ends on the single stranded DNA in a continuous fashion. The leading strand elongates toward the replication fork. Leading Strand Lagging Strand Key = Phosphate = Sugar = Adenine lymerase III = Thymine = Guanine = Cytosine

24. Then, on the leading strand, DNA Polymerase III adds the 5’ phosphate end of a free floating nucleotide to the exposed 3’ OH ends on the single stranded DNA in a continuous fashion. The leading strand elongates toward the replication fork. Leading Strand Lagging Strand Key = Phosphate = Sugar = Adenine = Thymine = Guanine e III = Cytosine

25. Lagging Strand Leading Strand Then, on the leading strand, DNA Polymerase III adds the 5’ phosphate end of a free floating nucleotide to the exposed 3’ OH ends on the single stranded DNA in a continuous fashion. The leading strand elongates toward the replication fork. Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

26. DNA Primase Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. Lagging Strand Leading Strand ` Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

27. Lagging Strand Leading Strand DNA Primase Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

28. Lagging Strand Leading Strand DNA Primase Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

29. DNA Primase Lagging Strand Leading Strand Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

30. 3’ Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. Lagging Strand DNA Primase 3’ 5’ Leading Strand 5’ Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine 3’ 5’ 5’

36. Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. DNA Primase Leading Strand Lagging Strand Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

37. Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. Leading Strand Lagging Strand Key = Phosphate = Sugar = Adenine DNA Primase = Thymine = Guanine = Cytosine

38. Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. Leading Strand Lagging Strand Key = Phosphate = Sugar = Adenine = Thymine Primase = Guanine = Cytosine

39. Lagging Strand Leading Strand Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. RNA Primer Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

40. Lagging Strand Leading Strand DNA Polymerase II Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. RNA Primer Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

41. DNA Polymerase II Lagging Strand Leading Strand Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. RNA Primer Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

42. DNA Polymerase II Lagging Strand Leading Strand Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. DNA When the DNA Polymerase II reaches the RNA primer, it turns into DNA. Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

43. DNA Polymerase II Lagging Strand Leading Strand Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. DNA When the DNA Polymerase II reaches the RNA primer, it turns into DNA. Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

44. DNA Polymerase II Lagging Strand Leading Strand Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. DNA Key = Phosphate = Sugar = Adenine = Thymine = Guanine = Cytosine

45. Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. Leading Strand Lagging Strand DNA Key = Phosphate = Sugar = Adenine = Thymine erase II = Guanine = Cytosine

46. Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. Leading Strand Lagging Strand DNA Key = Phosphate = Sugar = Adenine = Thymine = Guanine II = Cytosine

47. Lagging Strand Leading Strand Then, on the lagging strand, which has to be built discontinuously, a short RNA primer is synthesized from DNA primase. The primer is extended in a 5’ to 3’ direction, with short DNA segments called Okazaki fragments formed from DNA Polymerase II. DNA Key = Phosphate = Sugar = Adenine = Thymine Okazaki fragments = Guanine = Cytosine

48. Lagging Strand Leading Strand DNA Ligase Lastly, DNA Ligase forms a phophodiester bond to finalize the connection of Okazaki fragments. DNA Key = Phosphate = Sugar = Adenine = Thymine Okazaki fragments = Guanine = Cytosine

49. DNA Ligase Lagging Strand Leading Strand Lastly, DNA Ligase forms a phophodiester bond to finalize the connection of Okazaki fragments. DNA Key = Phosphate = Sugar = Adenine = Thymine Okazaki fragments = Guanine = Cytosine

55. Lastly, DNA Ligase forms a phophodiester bond to finalize the connection of Okazaki fragments. Leading Strand Lagging Strand DNA Key = Phosphate = Sugar = Adenine DNA Ligase = Thymine Okazaki fragments = Guanine = Cytosine

56. Lastly, DNA Ligase forms a phophodiester bond to finalize the connection of Okazaki fragments. Leading Strand Lagging Strand DNA Key = Phosphate = Sugar = Adenine A Ligase = Thymine 5’ Okazaki fragments = Guanine = Cytosine

57. Lastly, DNA Ligase forms a phophodiester bond to finalize the connection of Okazaki fragments. Leading Strand Lagging Strand DNA Key = Phosphate = Sugar = Adenine = Thymine ase Okazaki fragments 5’ = Guanine = Cytosine

58. 5’ 3’5’ 3’ Lastly, DNA Ligase forms a phophodiester bond to finalize the connection of Okazaki fragments. Leading Strand Lagging Strand DNA = Phosphate = Sugar = Adenine = Thymine Okazaki fragments 3’ Key 5’ 3’ 5’ = Guanine = Cytosine

59. Why Does DNA Need to Replicate? • DNA needs to replicate because when a cell in your body divides, in order for your body to grow or repair itself it must also duplicate the cell's DNA. This is so the cell will then have it's own set of directions to know how to continue replicating.

60. In My Own Words... • Telomeres- keep chromosomes from becoming attached to each other accidentally. • Okazaki Fragment- a section of complimentary strands of DNA formed when the enzyme DNA Ligase is present. • DNA Ligase- an enzyme that “stitches” a new complimentary strand of DNA called an okazaki fragment. • Telomerase- an enzyme that helps a cell maintain the length of their telomeres.

61. In My Own Words… (Continued) • Cancer- expresses the enzyme telomerase, which helps a tumor to grow. • Transplanted Cells- cells that have been taken, added to, and then given back • Cloning- taking a piece of something and making another copy • Aging- the steady shrinking of cells in the body

62. Mutations (Mistakes) • If there are any mistakes while replicating DNA, it will result in the mutation of a gene. An organism can only have up to 3 mutations, or it cannot live. Sometimes, mutations are minor, while other times, they can change one’s whole genetic makeup. For example, a mutation can result in the crossing over of a 21st chromosome, resulting in one having Down’s Syndrome.

63. Where in Mitosis Does DNA Replication Happen? • DNA replication happens in S Phase and also in cytokinesis, or the last phase of mitosis.

64. Where in the Cell? •DNA replication happens in the nucleus of a cell.

65. Works Cited • http://wiki.answers.com/Q/What_happens_if_there_ is_a_error_in_DNA_replication?#slide=6 • http://www.nature.com/scitable/topicpage/dnareplication-and-causes-of-mutation-409 • http://www.chemguide.co.uk/organicprops/aminoac ids/dna6.html • http://www.biology.ewu.edu/aHerr/Genetics/Bio310/ Pages/ch13pges/ch13note.html • http://www.astrochem.org/sci/Nucleobases.php

66. The End

DNA Model

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DNA Model