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Replication of DNA TEST CH. 17 Thursday April 21 st Section 17.3 p. 582-588

Replication of DNA TEST CH. 17 Thursday April 21 st Section 17.3 p. 582-588 The first 13 slides of this presentation correct the 32 questions on the Guided reading lesson about DNA Replication. GUIDED Reading Lesson. Replication of DNA Section 17.3 INTRODUCTION p.582

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Replication of DNA TEST CH. 17 Thursday April 21 st Section 17.3 p. 582-588

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  1. Replication of DNA TEST CH. 17 Thursday April 21st Section 17.3 p. 582-588 The first 13 slides of this presentation correct the 32 questions on the Guided reading lesson about DNA Replication. GUIDED Reading Lesson

  2. Replication of DNA Section 17.3 INTRODUCTION p.582 • How many base pairs are in the human genome? • 6 billion • How long would it take a typist to type those one letter codes if he could type at 60 words a minute? • 30years • How long does it take the cell to copy the human genome? • A Few hours • Replication of DNA is very accurate. How accurate is it? • 1 error per 1 billion nucleotide pairs

  3. Replication of DNA Section 17.3 THE PROCESS OF REPLICATION p.582 5. Replication of DNA is semi-conservative. What does that mean? • ½ is new and ½ is from the parent DNA 6. What are the three main stages of DNA replication? • Initiation; elongation; Termination

  4. Replication of DNA Section 17.3 Initation 7. What is a replication origin? 8. How many replication origins does prokaryotic DNA have? 9. How many replication origins does eukaryotic DNA have? 10. What is a replication bubble?

  5. Replication of DNA Section 17.3 Initation 11. What role does DNA polymerase play in DNA replication? 12. What is a replication fork? 13. How many replication forks does a replication bubble have? 14. What is the role of helicases?

  6. Replication of DNA Section 17.3 Initation 15. Using fig. 17.21 as a guide draw a strand of Eukaryotic DNA and label the following parts a. Replication origin b. Replication loop c. Replication fork d. Location where DNA polymerase operates e. Location where Helicases operate

  7. Replication of DNA Section 17.3 Initation 15. Using fig. 17.21 as a guide draw a strand of Eukaryotic DNA and label the following parts a. Replication origin b. Replication loop c. Replication fork d. Location where DNA polymerase operates e. Location where Helicases operate

  8. Replication of DNA Section 17.3 Initation 16. How fast does the bacterium E. coli unwind its DNA? • 4500RPM 17. How fast does the replication fork move in the bacterium E. coli? • 650 nucleotides per second

  9. Replication of DNA Section 17.3 Elongation 18. What is the function of the primer? 19. How many primers are needed on the lead strand? 20. How many primers are needed on the lagging strand? 21. What are Okazaki fragments?

  10. Replication of DNA Section 17.3 Elongation 22. In which direction does DNA replication occur on the leading strand? 23. In which direction does DNA replication occur on the lagginging strand?

  11. Replication of DNA Section 17.3 Elongation 24. What is the function of DNA ligase? 25. Which strand requires DNA Ligase? 26. What is Primase? 27. What is the role of the RNA Primer?

  12. Replication of DNA Section 17.3 TERMINATION p.585 28. What are telomeres? • Repeating TTAGGG nucleotides found at the end of a chromosome that are not replicated during DNA replication. They do not direct cell development so their loss does not affect the cell. 29. How much DNA is lost with each replication? • 100 base pairs 30. What is telomerase? • An enzyme the extends telomeres (related to long life)

  13. Replication of DNA Section 17.3 PROOFREADING AND CORRECTION p. 586 31. How does the DNA polymerase detect that the wrong nucleotide was inserted? • Absence of hydrogen bonds 32. Sketch a replication machine.

  14. When does Replication of DNA Occur? Interphase of Meiosis & Mitosis

  15. 1 Initiation 2 Elongation 3 Termination What are the three phases of DNA Replication? Watch the whole process at http://www.johnkyrk.com/DNAreplication.html

  16. Initiation: • A portion of the double helix is unwound by a helicase. • Helicase is an enzyme that breaks the helix apart at a region rich in A-T binds. • Remember A-T bonds only have 2 hydrogen bonds whereas C-G bonds have 3 hydrogen bonds. • Eukaryotic DNA often has several origins of replication Initiation of DNA Replication

  17. Remember A-T bonds only have 2 hydrogen bonds whereas C-G bonds have 3 hydrogen bonds. Initiation of DNA Replication

  18. DNA polymerase uses the exposed Parental DNA as a template for assembling 2 semiconserved strands of DNA. • This action causes Replication bubbles Elongation of DNA Replication

  19. A molecule of a DNA polymerase binds to one strand of the DNA and begins moving along it in the 3' to 5' direction, using it as a template for assembling a leading strand of nucleotides and reforming a double helix. In eukaryotes, this molecule is called DNA polymerase delta (δ). Elongation of the Leading strand in DNA Replication

  20. Because DNA synthesis can only occur 5' to 3', a molecule of a second type of DNA polymerase (epsilon, ε, in eukaryotes) binds to the other template strand as the double helix opens. This molecule must synthesize discontinuous segments of polynucleotides (called Okazaki fragments). Another enzyme, DNA ligase I then stitches these together into the lagging strand. Elongation of the Lagging strand

  21. The beginning end of the lagging and leading strand can not be replicated. telomere – specialized non-transcribed structure typically rich in G nucleotides, at the end of each chromosome. The use of telomeres protects us against the loss of genetic material during replication Termination

  22. DNA Polymerase check for unattached hydrogen bonds. C-G must have 3 bonds and A-T must have 2 bonds. Therefore the wrong combination would leave a free H bond. DNA Polymerase fixes MOST errors Proof Reading

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