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Unlocking DNA Mysteries: From Discovery to Structure

Explore the fascinating world of molecular genetics as we delve into the discovery of DNA as the genetic material, its replication, and role in gene regulation and mutation. Learn about the key experiments and scientists who unlocked the secrets of DNA, its double helix structure, and the significance of nucleotides. Discover how Watson and Crick's model revolutionized our understanding of DNA. Join us on a journey through the molecular genetic blueprint of life.

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Unlocking DNA Mysteries: From Discovery to Structure

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  1. Chapter 12 Molecular Genetics Section 1: DNA: The Genetic Material Section2: Replication of DNA Section 3: DNA, RNA, and Protein Section 4: Gene Regulation and Mutation

  2. BELLRINGER!!! Answer each question below in your science notebook. • What questions do you think explorers asked when they • first saw the Great Sphinx? • 2. If you were to study the Great Sphinx, what do you think • you could learn about the people who built it? • 3. What questions do you think scientists asked when they • began to understand the genetic basis of life?

  3. Answers will vary. Students • might suggest that explorers • wanted to know who built the • Sphinx, why, and how. • 2. Answers will vary. Students • might suggest that they could • learn about the technological • capabilities, culture, or • beliefs of the people involved. • 3. Answers will vary. Students • might suggest that, among • other things, scientists • wanted to know how genetic • information was replicated • and transported to new cells.

  4. How do we know how to build things?

  5. DNA: The Genetic Material(Section 12.1) MAIN IDEA:The discovery that DNA is the genetic code involved many experiments.

  6. Objectives: Summarize the experiments leading to the discovery of DNA as the genetic material. Diagram and label the basic structure of DNA. Describe the basic structure of the eukaryotic chromosome. Molecular Genetics Chapter 12 DNA: The Genetic Material(Section 12.1)

  7. nucleic acid – complex biomolecule that stores cellular information in the form of a code protein – organic compound made of amino acids joined by peptide bonds; primary building block of organisms macromolecule – large molecule formed by joining smaller organic molecules together Molecular Genetics Chapter 12 Review Vocabulary

  8. double helix nucleosome Molecular Genetics Chapter 12 New Vocabulary

  9. Molecular Genetics Chapter 12 DNA: The Genetic Material(Section 12.1) Scientists knew that genetic information was carried on the chromosome in eukaryotic cells, and that the two main components of chromosomes are DNA and protein.

  10. Molecular Genetics Chapter 12 THE BLUEPRINT: DNA or proteins? The race to find the genetic material was split into two groups: those who thought the genetic material was protein and those who thought the genetic material was DNA.

  11. Molecular Genetics Chapter 12 12.1 DNA: The Genetic Material Griffith • Performed the first major experiment that led to the discovery of DNA as the genetic material.

  12. Molecular Genetics Chapter 12 12.1 DNA: The Genetic Material Avery • Identified the molecule that transformed the R strain of bacteria into the S strain • Concluded that when the S cells were killed, DNA was released. • R bacteria incorporated this DNA into their cells and changed into S cells.

  13. Molecular Genetics Chapter 12 12.1 DNA: The Genetic Material Hershey and Chase • Used radioactive labeling (via viruses) to trace the DNA and protein. • Concluded that the viral DNA was injected into the cell and provided the genetic information needed to produce new viruses

  14. Molecular Genetics Chapter 12 12.1 DNA: The Genetic Material DNA Structure • Nucleotides • consist of a five-carbon • 1) sugar, a 2) phosphate • group, and a nitrogenous • 3) base

  15. Molecular Genetics Chapter 12 12.1 DNA: The Genetic Material Chargaff • Chargaff’s rule: C = G and A = T

  16. Molecular Genetics Chapter 12 The Pieces of the Puzzle • Franklin’s DiscoveryChemist Rosalind Franklin was able to make images of DNA molecules by using X-ray diffraction.

  17. DNA = “double helix” or “twisted ladder”

  18. Molecular Genetics Chapter 12 12.1 DNA: The Genetic Material Watson and Crick • Built a model of the double helix • that conformed to the others’ • research two outside strands consist of alternating deoxyribose and phosphate cytosine and guanine bases pair to each other by three hydrogen bonds thymine and adenine bases pair to each other by two hydrogen bonds

  19. Molecular Genetics Chapter 12 DNA Structure • DNA often is compared to a twisted ladder. • Rails of the ladder are represented by the alternating deoxyribose and phosphate. • The pairs of bases (cytosine–guanine or thymine–adenine) form the steps.

  20. http://glencoe.mcgraw-hill.com/sites/0078695104/student_view0/unit3/chapter12/concepts_in_motion.html#http://glencoe.mcgraw-hill.com/sites/0078695104/student_view0/unit3/chapter12/concepts_in_motion.html# Molecular Genetics Chapter 12

  21. Molecular Genetics Chapter 12 12.1 DNA: The Genetic Material Orientation • On the top rail, the strand is said to be oriented 5′ to 3′. • The strand on the bottom runs in the opposite direction and is oriented 3′ to 5′.

  22. Alabama Science in Motion Lab “DNA Model Kit” Molecular Genetics Chapter 12

  23. Molecular Genetics Chapter 12 12.1 DNA: The Genetic Material Chromosome Structure • DNA coils around histones to form nucleosomes, which coil to form chromatin fibers. • The chromatin fibers supercoil to form chromosomes that are visible in the metaphase stage of mitosis.

  24. In prokaryotes, the DNA molecule is contained in the cytoplasm and consists mainly of a ring of DNA and associated proteins. Eukaryotic DNA is organized into individual chromosomes. If a DNA strand 140 million nucleotides long was laid out in a straight line, it would be about five centimeters long. Chromosome Structure

  25. Section 12.1 Summary • Griffith’s bacterial experiment and Avery’s explanation first indicated that DNA is genetic material. • The Hershey-Chase experiment provided evidence that DNA is the genetic material of viruses. • Chargaff’s rule states that, in DNA, the amount of cytosine equals the amount of guanine and the amount of thymine equals the amount of adenine. • The work of Watson, Crick, Franklin, and Wilkins provided evidence of the double-helix structure of DNA.

  26. MAIN IDEA: DNA replicates by making a strand that is complementary to each original strand. Molecular Genetics Chapter 12 Replication of DNA

  27. Replication of DNA(Section 12.2) Objectives • Summarize the role of the enzymes involved in the replication of DNA. • Explain how leading and lagging strands are synthesized differently.

  28. Review Vocabulary template – a molecule of DNA that is a pattern for synthesis for a new DNA molecule

  29. New Vocabulary semiconservative replication DNA polymerase Okazaki fragment

  30. Parental strands of DNA separate, serve as templates, and produce DNA molecules that have one strand of parental DNA and Molecular Genetics one strand of new DNA. Chapter 12 12.2 Replication of DNA Semiconservative Replication

  31. Molecular Genetics Chapter 12 12.2 Replication of DNA Unwinding • DNAhelicase,an enzyme, is responsible for unwinding and unzipping the double helix. • RNA primase adds a short segment of RNA, called an RNA primer, on each DNA strand.

  32. Molecular Genetics Chapter 12 12.2 Replication of DNA Base pairing • DNA polymerase continues adding appropriate nucleotides to the chain by adding to the 3′ end of the new DNA strand.

  33. Molecular Genetics Chapter 12

  34. Molecular Genetics Chapter 12 12.2 Replication of DNA • One strand is called the leading strand and is elongated as the DNA unwinds. • The other strand of DNA, called the lagging strand, elongates away from the replication fork. • The lagging strand is synthesized discontinuously into small segments, called Okazaki fragments.

  35. Molecular Genetics Chapter 12 12.2 Replication of DNA Joining • DNA polymerase removes the RNA primer and fills in the place with DNA nucleotides. • DNA ligase links the two sections.

  36. Molecular Genetics Chapter 12 12.2 Replication of DNA Comparing DNA Replication in Eukaryotes and Prokaryotes • Eukaryotic DNA unwinds in multiple areas as DNA is replicated. • In prokaryotes, the circular DNA strand is opened at one origin of replication. • Prokaryotes DNA typically is shorter than eukaryotic DNA and remains in the cytoplasm.

  37. Section 12.2 Summary • The enzymes DNA helicase, RNA primase, DNA polymerase, and DNA ligase are involved in DNA replication. • The leading strand is synthesized continuously, but the lagging strand is synthesized discontinuously, forming Okazaki fragments. • Prokaryotic DNA opens at a single origin of replication, whereas eukaryotic DNA has multiple areas of replication.

  38. Molecular Genetics Chapter 12 DNA, RNA, and Protein(Section 12.3) MAIN IDEA: DNA codes for RNA, which guides protein synthesis.

  39. DNA, RNA, and Protein(Section 12.3) Objectives: • Explain how messenger RNA, ribosomal RNA, and transfer RNA are involved in the transcription and translation of genes. • Summarize the role of RNA polymerase in the synthesis of messenger RNA. • Describe how the code of DNA is translated into messenger RNA and is utilized to synthesize a particular protein.

  40. synthesis – the composition or combination of parts to form a whole. (Glencoe) synthesis – the uniting or building up of substances into a compound. (Webster’s) Molecular Genetics Chapter 12 Review Vocabulary

  41. RNA messenger RNA (mRNA) ribosomal RNA (rRNA) transfer RNA (tRNA) transcription RNA polymerase codon intron exon translation Molecular Genetics Chapter 12 New Vocabulary

  42. Molecular Genetics Chapter 12 12.3 DNA, RNA, and Protein Central Dogma (reading and expressing genes = DNA > RNA > protein) “DNA codes for RNA which guides the synthesis of proteins.” • RNA • Contains the sugar ribose and the base uracil • Usually is single stranded dogma – something held as an established opinion; a point of view

  43. Molecular Genetics Chapter 12 12.3 DNA, RNA, and Protein Messenger RNA (mRNA) • Long strands of RNA nucleotides that are formed complementary to one strand of DNA Ribosomal RNA (rRNA) • Associates with proteins to form ribosomes in the cytoplasm Transfer RNA (tRNA) • Smaller segments of RNA nucleotides that transport amino acids to the ribosome

  44. Molecular Genetics Chapter 12 12.3 DNA, RNA, and Protein

  45. Molecular Genetics Chapter 12

  46. Molecular Genetics • DNA is unzipped in the nucleus and RNA polymerasebinds to a specific section where an mRNA will be synthesized. Chapter 12 12.3 DNA, RNA, and Protein Transcription • Through transcription, the DNA code is transferred to mRNA in the nucleus.

  47. Molecular Genetics Chapter 12

  48. Molecular Genetics Chapter 12 12.3 DNA, RNA, and Protein RNA Processing • The code on the DNA is interrupted periodically by sequences that are not in the final mRNA. • Intervening sequences are called introns. • Remaining pieces of DNA that serve as the coding sequences are called exons. DNA and Genes

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