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DNA and its Processes

DNA and its Processes. Chapter 12 Material on Midterm. Section 12-1: DNA. Key Concepts List the conclusions of Griffith, Avery, Hershey-Chase, Franklin, Chargaff, and Watson-Crick drew from their experiments Describe Watson and Crick’s model of the DNA molecule. Section 12-1: DNA.

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DNA and its Processes

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  1. DNA and its Processes • Chapter 12 • Material on Midterm

  2. Section 12-1: DNA • Key Concepts • List the conclusions of Griffith, Avery, Hershey-Chase, Franklin, Chargaff, and Watson-Crick drew from their experiments • Describe Watson and Crick’s model of the DNA molecule

  3. Section 12-1: DNA • There are several scientists that have contributed to our understanding of DNA • Griffith • Avery • Hershey-Chase • Chargaff • Franklin • Watson-Crick

  4. Griffith

  5. Section 12-1: DNA • Answer these questions • What are the two types of strains? • Seeing what happens to mice injected with virulent strains, what do you think “virulent” means?

  6. Section 12-1: DNA • Frederick Griffith • Responsible for transformation • Process in which one strain of bacteria is changed by gene(s) from another strain • Worked with mice and pneumonia • Mice that were injected with rough or heat-killed smooth strain lived • Mice that had the smooth strain died • Mice that had the heat-killed smooth but living rough died. • Why?

  7. Avery

  8. Section 12-1: DNA • Answer these questions • What does the “S” strain do to mice again? • What enzyme destroys proteins? • What enzyme destroys RNA? • What enzyme destroys DNA? • Which enzyme prevented the smooth strain to grow?

  9. Section 12-1: DNA • Oswald Avery • Responsible for determining that the molecule important in transformation was nucleic acid DNA • Took heat-killed bacteria and made extract • Enzymes for lipids, proteins, and carbohydrates—no effect • Still transformation of smooth strain • Enzymes for nucleic acid—major effect • Smooth strain not transformed

  10. Hershey & Chase

  11. Section 12-1: DNA • Answer these questions • Why did they use radioactive sulfur for identifying protein? (Think about the elements in protein!) • Why did they use radioactive phosphorus for identifying DNA? (Think about the elements in DNA!) • Which is more dense—DNA or protein? • What remained in the bacteria—DNA or protein?

  12. Section 12-1: DNA • Alfred Hershey and Martha Chase • Determined that the genetic material is made out of DNA, not protein • Used radioactive labels • Sulfur-35 for protein—CHOSN for protein • Phosphorus-32 for nucleic acid—CHOPN • Genetic material glowed with P-32…DNA

  13. Section 12-1: DNA • Chargaff • Looked at numerous organisms • Compared concentrations of nitrogenous bases (bases) • What do you notice? __________________________ Chargaff had no idea WHY this was happening!

  14. Section 12-1: DNA • Rosalind Franklin • Used X-ray diffraction to study image of DNA • Helical shape • Twisted strands • 2 strands • Bases near middle

  15. Section 12-1: DNA • What words do you not recognize in the paper? Make a list. • How does the length of the paper compare to a normal scientific article (around 5 pages)? • Why don’t they like Pauling’s and Corey’s model (2 reasons)? • How many helical chains do they propose? • How many base pairs (residues) are in the chain before it repeats? • Where are the phosphates located? • What type of bond joins the bases? • What base pairing rules do they suggest? • What is the sugar?

  16. Section 12-1: DNA • Built 3-D models of DNA • Used work of everyone before them • Model: double helix • Twisted ladder • H-bonds between nitrogenous bases • Base pairing: A with T, G with C • EXPLAINS CHARGAFF

  17. SUM IT UP!

  18. 12-1: DNA • Components & Structure of DNA • What are the monomers and polymers of nucleic acid? ____________ ___________ • Double-stranded • Each nucleotide is made up of three parts • Phosphate group • Nitrogenous base • 4 types • 5-carbon sugar • Deoxyribose

  19. 12-1: DNA • 4 different nitrogenous bases • Guanine (G) • Adenine (A) • Cytosine (C) • Thymine (T) A pairs up with T, and G pairs up with C

  20. 12-1: DNA The Sugar and the Phosphate group are the BACKBONE of DNA (covalent bonds) • Role of hydrogen bonds • SUMMARY:

  21. Section 12-1: DNA • Purines • 2 rings • Nucleotide adenine • Nucleotide guanine • Pyridimes • 1 ring • Nucleotide thymine • Nucleotide cytosine Two styles of nucleotides based on size Ones with “y” are pyrimidines Longer word; less rings

  22. SUMITUP

  23. 12-1: DNA • Please answer the following on your Key Concepts Sheet • List the conclusions of Griffith, Avery, Hershey-Chase, Franklin, Chargaff, and Watson-Crick drew from their experiments • Describe Watson and Crick’s model of the DNA molecule

  24. 12-2: Chromosomes and DNA Replication • Key Concepts • Explain how DNA condenses • Explain how DNA is replicated

  25. 12-2: Chromosomes and DNA Replication • Think back to mitosis…What happens in the “S” phase of interphase?

  26. 12-2: Chromosomes and DNA Replication • When DNA goes through mitosis, it condenses for easy sorting and separation • When its thin, it’s chromatin • Wrapped around histone proteins like beads on a string • Coils up • Coils coil up • A chromosome is the very condensed form of DNA

  27. 12-2: Chromosomes and DNA Replication • The path to condensation

  28. 12-2: Chromosomes and DNA Replication • Your turn!

  29. DNA condensation • DNA replication • Goal: two identical strands of DNA • General steps: • Unzip double-strands • Add new base pairs • Clean up

  30. 12-2: Chromosomes and DNA Replication If I were an enzyme… • DNA Replication • DNA helicase comes in and unzips the double helix • RNA primers are added • DNA polymerase ‘lands’ on primers and adds new base pairs • Two identical daughter strands result

  31. 12-2: Chromosomes and DNA Replication • Parent strand • DNA helicase separates • DNA Polymerase adds • DNA ligase cleans up

  32. 12-2: Chromosomes and DNA Replication • It the parent strand is AATCCG, what will the result be? TTAGGC • If we are looking at ONE HALF of a DNA strand for DNA polymerase to add bases to, what would the other half be? GTCAGTTCCATCCTAG

  33. 12-2: Chromosomes and DNA Replication • SUM IT UP!

  34. 12-2: Chromosomes and DNA Replication • Please answer the following on your Key Concepts Sheet • Explain how DNA condenses • Explain how DNA is replicated

  35. 12-3: RNA and Protein Synthesis • Key Concepts • What are the three main types and functions of RNA? • What occurs during transcription? • What occurs during translation?

  36. 12-3: RNA and Protein Synthesis • Components & Structure of RNA • What are the monomers and polymers of nucleic acid? ____________ ___________ • Single-stranded • Each nucleotide is made up of three parts • Phosphate group • Nitrogenous base • 4 types • 5-carbon sugar • ribose

  37. 12-3: RNA and Protein Synthesis • 4 different nitrogenous bases • Guanine (G) • Adenine (A) • Cytosine (C) • Uracil (U) A pairs up with U, and G pairs up with C

  38. 12-3: RNA and Protein Synthesis

  39. 12-3: RNA and Protein Synthesis

  40. 12-3: RNA and Protein Synthesis • Sum it up!

  41. 12-3: RNA and Protein Synthesis • Messenger RNA • mRNA • Carries copies of instructions for the assembly of amino acids into proteins from DNA to the rest of the cell Involved in protein synthesis

  42. 12-3: RNA and Protein Synthesis • Ribosomal RNA • rRNA • RNA that makes up a major part of the ribosome • Site of protein synthesis ALSO involved in protein synthesis

  43. 12-3: RNA and Protein Synthesis • Transfer RNA • tRNA • Transfers amino acid to ribosome during protein synthesis And STILL involved in protein synthesis

  44. SUM IT UP

  45. 12-3: RNA and Protein Synthesis • Transcription • Goal: make a strand of mRNA that “pairs up” with a template strand of DNA • Complementary strand • Steps • Unzip double helix • Add in RNA bases • Break away and leave nucleus

  46. 12-3: RNA and Protein Synthesis • Transcription • RNA polymerase does the job of DNA helicase and DNA polymerase combined • Unzips and adds bases, but only to the TEMPLATE strand (coding strand)

  47. 12-3: RNA and Protein Synthesis • It the parent strand is AATCCG, what will the result be if the TOP TTAGGCstrand istranscribed? • If we are looking at ONE HALF of a DNA strand for RNA polymerase to add bases to, what would the other half be? GTCAGTTCCATCCTAG

  48. 12-3: RNA and Protein Synthesis • SUM IT UP • Write TWO LINES about the similarities between replication and transcription • Write TWO LINES about the differences between replication and transcription

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