Ap Biology Chap 16-19 Terms
Frederick Griffith | This person made an experiment that involved injecting mice with pneumonia: smooth S cells, rough R cells, heat-killed S cells, and heat-killed S cells with living R cells. | Avery, McCarty, and MacLeod | First to show that DNA was the genetic material, but not believed. Repeated Griffith's experiment, but subjected the strains to different enzymes, isolating RNA, DNA, lipids, carbohydrates, and proteins. Only the DNA killed the mice; the others had the mice survive. | Hershey and Chase | Used T4 bacteriophages in radioactive phosphorus to track DNA and radioactive sulfur to track proteins to determine what is the transformational material in genes. Radioactive phosphorus found in host bacteria, but no sulfur, proving once and for all DNA was the genetic material. | Erwin Chagraff | Analyzed the base composition of DNA and saw that it varied from species to species (shows the diversity of species). He also found that the amount of A nucleotides equaled the number of T nucleotides, and the number of C nucleotides equaled the number of G nucleotides. | Wilkins and Franklin | Used a technique called x-ray crystallography to produce a picture of the DNA molecule | Watson and Crick | Figured out structure of DNA was a double helix, and used Chagraff's observations to determine that purines pair with pyrimidines to maintain equidistance in the helix. (A with T and C with G) | Conservative Model | The parental double helix is copied as a full double helix; proved false | Semi-Conservative Model | The parental double helix is unzipped, and copied as individual template strands; Watson and Crick assumed this was correct, and it is | Dispersive Model | The parental double helix is copied in fragments; proved false | Meselson and Stahl | Proved that DNA replicates in a semiconservative fashion, confirming Watson and Crick's hypothesis. Cultured bacteria in a medium containing heavy nitrogen (15N) and then a medium containing light