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Chapter 11: DNA and Its Role in Heredity CHAPTER 11 DNA and Its Role in Heredity Chapter 11: DNA and Its Role in Heredity Chapter 11: DNA and Its Role in Heredity DNA: The Genetic Material The Structure of DNA DNA Replication The Mechanism of DNA Replication DNA Proofreading and Repair Practical Applications of DNA Replication Chapter 11: DNA and Its Role in Heredity DNA: The Genetic Material • In addition to circumstantial evidence, two experiments demonstrated that DNA is the genetic material. 3 Chapter 11: DNA and Its Role in Heredity DNA: The Genetic Material • In one, virulent strain pneumococcus bacteria DNA genetically transformed nonvirulent bacteria into virulent bacteria. Review Figure 11.1 4 Chapter 11: DNA and Its Role in Heredity Figure 11.1 Figure 11.1 figure 11-01.jpg Chapter 11: DNA and Its Role in Heredity DNA: The Genetic Material • In a second, labeled viruses were incubated with host bacteria. • Labeled viral DNA entered host cells, producing hundreds of label-bearing viruses. Review Figures 11.2 and 11.3 6 Chapter 11: DNA and Its Role in Heredity Figure 11.2 – Part 1 Figure 11.2 – Part 1 figure 11-02a.jpg Chapter 11: DNA and Its Role in Heredity figure 11-02b.jpg Figure 11.2 – Part 2 Figure 11.2 – Part 2 Chapter 11: DNA and Its Role in Heredity figure 11-03.jpg Figure 11.3 Figure 11.3 Chapter 11: DNA and Its Role in Heredity The Structure of DNA • X-ray crystallography showed that the DNA molecule is a helix. Review Figure 11.4 10 Chapter 11: DNA and Its Role in Heredity Figure 11.4 Figure 11.4 figure 11-04.jpg Chapter 11: DNA and Its Role in Heredity The Structure of DNA • DNA is composed of nucleotides, each containing adenine, cytosine, thymine, or guanine. • There are equal amounts of adenine and thymine and equal amounts of guanine and cytosine. Review Figure 11.5 12 Chapter 11: DNA and Its Role in Heredity Figure 11.5 Figure 11.5 figure 11-05.jpg Chapter 11: DNA and Its Role in Heredity The Structure of DNA • Watson and Crick proposed that DNA is a double-stranded helix with antiparallel strands, and with bases linked by hydrogen bonding. • Their model accounts for genetic information, mutation, and replication functions of DNA. Review Figures 11.6 and 11.7 14 Chapter 11: DNA and Its Role in Heredity Figure 11.6 Figure 11.6 figure 11-06.jpg Chapter 11: DNA and Its Role in Heredity figure 11-07a.jpg Figure 11.7 – Part 1 Figure 11.7 - Part 1 Chapter 11: DNA and Its Role in Heredity figure 11-07b.jpg Figure 11.7 – Part 2 Figure 11.7 – Part 2 Chapter 11: DNA and Its Role in Heredity DNA Replication • Semiconservative, conservative, and dispersive models for DNA replication were hypothesized. Review Figure 11.8 18 Chapter 11: DNA and Its Role in Heredity figure 11-08.jpg Figure 11.8 Figure 11.8 Chapter 11: DNA and Its Role in Heredity DNA Replication • Meselson and Stahl’s experiment proved replication of DNA to be semiconservative. • A parent strand is a template for synthesis of a new strand. • Two replicated DNA helices contain one parent strand and one synthesized strand each. Review Figures 11.9 and 11.10 20 Chapter 11: DNA and Its Role in Heredity figure 11-09.jpg Figure 11.9 Figure 11.9 Chapter 11: DNA and Its Role in Heredity figure 11-10.jpg Figure 11.10 Figure 11.10 Chapter 11: DNA and Its Role in Heredity The Mechanism of DNA Replication • DNA polymerase catalyzes nucleotides to the 3’ end. • Nucleotides are added by complementary base pairing with the template strand. • The substrates, deoxyribonucleoside triphosphates, are hydrolyzed as added, releasing energy for DNA synthesis. Review Figure 11.11 23 Chapter 11: DNA and Its Role in Heredity Figure 11.11 Figure 11.11 figure 11-11.jpg Chapter 11: DNA and Its Role in Heredity The Mechanism of DNA Replication • The DNA replication complex is in a fixed location and DNA is threaded through it for replication. Review Figure 11.12 25 Chapter 11: DNA and Its Role in Heredity Figure 11.12 Figure 11.12 figure 11-12.jpg Chapter 11: DNA and Its Role in Heredity The Mechanism of DNA Replication • Many proteins assist in DNA replication. • DNA helicases unwind the double helix, the template strands are stabilized by other proteins. 27 Chapter 11: DNA and Its Role in Heredity The Mechanism of DNA Replication • Prokaryotes have a single origin of replication; eukaryotes have many. Replication for each proceeds in both directions from an origin of replication. Review Figure 11.13 28 Chapter 11: DNA and Its Role in Heredity figure 11-13.jpg Figure 11.13 Figure 11.13 Chapter 11: DNA and Its Role in Heredity The Mechanism of DNA Replication • An RNA primase catalyzes the synthesis of short RNA primers, and to which nucleotides are added. Review Figure 11.15 30 Chapter 11: DNA and Its Role in Heredity figure 11-15.jpg Figure 11.15 Figure 11.15 Chapter 11: DNA and Its Role in Heredity The Mechanism of DNA Replication • DNA polymerase action causes the leading strand to grow in the 5’-to-3’ direction until replication of that section of DNA is complete. • RNA primer is degraded and DNA replaces it. 32 Chapter 11: DNA and Its Role in Heredity The Mechanism of DNA Replication • On the lagging strand, growing in the other direction, DNA is made in the 5’-to-3’ direction but synthesis is discontinuous: • DNA is added as short fragments to primers, then the polymerase skips past the 5’ end to make the next fragment. Review Figures 11.16, 11.17 and 11.18 33 Chapter 11: DNA and Its Role in Heredity Figure 11.16 Figure 11.16 figure 11-16.jpg Chapter 11: DNA and Its Role in Heredity figure 11-17.jpg Figure 11.17 Figure 11.17 Chapter 11: DNA and Its Role in Heredity figure 11-18.jpg Figur e 11.18 Figure 11.18 Chapter 11: DNA and Its Role in Heredity DNA Proofreading and Repair • There is about one error in 106 nucleotide bases added in DNA replication, repaired by: proofreading, mismatch repair, and excision repair. • DNA repair mechanisms lower the error rate to about one base in 109. Review Figure 11.19 37 Chapter 11: DNA and Its Role in Heredity Figure 11.19 Figure 11.19 figure 11-19.jpg Chapter 11: DNA and Its Role in Heredity DNA Proofreading and Repair • Although energetically costly and somewhat redundant, DNA repair is crucial to the survival of the cell. 39 Chapter 11: DNA and Its Role in Heredity Practical Applications of DNA Replication • The principles of DNA replication can be used to determine the nucleotide sequence of DNA. Review Figure 11.20 40 Chapter 11: DNA and Its Role in Heredity Figure 11.20 – Part 1 Figure 11.20 – Part 1 figure 11-20a.jpg Chapter 11: DNA and Its Role in Heredity Figure 11.20 - Part 2 Figure 11.20 – Part 2 figure 11-20b.jpg Chapter 11: DNA and Its Role in Heredity Practical Applications of DNA Replication • The polymerase chain reaction technique uses DNA polymerases to repeatedly replicate DNA in the test tube. Review Figure 11.21 43 Chapter 11: DNA and Its Role in Heredity Figure 11.21 Figure 11.21 figure 11-21.jpg