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Griffith S vs R, transform princp/Oswald, maclyn, colin dna is gen material/Hershey and Chase bacteriophage/Euk gen material evidence, Recombinant DNA/ DNA RNA strucs Frederick Griffith vaccine against the bacterium Streptococcus pneumoniae. Some strains of S. pneumoniae produce a polysaccharide capsule found on the outside of the cell. Those strains of with capsules are more virulent than strains that do not produce a capsule. Further, those strains with capsules form smooth colonies (called type S) on bacterial culture media, those without capsules form rough colonies (called type R). When smooth strains are injected into mice, the mice die. The smooth strain of S. pneumoniae can be cultured from the blood of the dead mouse. When rough strains are injected into mice, the mice survive. No bacteria can be isolated from the blood of the living mouse. When smooth are heat-killed and injected into mice, the mice survive. When live type R bacteria are mixed with heat-killed type S bacteria and injected into mice, the mice die. The bacteria isolated from the dead mice are live type S bacteria. S bacteria transformed the living type R bacteria to type S bacteria. cells that were transformed from type R to type S passed the type S trait to all of their progeny. Thus, the chemical responsible for transformation (transforming principle) has properties of the genetic material (can change phenotype, is inherited); however, the actual chemical responsible for transformation was unknown. Oswald Avery, Maclyn McCarty, and Colin MacLeod wanted to identify the transforming principle released by heat-killed type S bacteria, three candidate chemicals: DNA, RNA, and protein. When type R bacterial cells were mixed with material from heat-killed type S cells in the presence of ribonuclease (RNase) to digest RNA, t he type R bacteria were still transformed into type S bacteria. Thus, digestion of RNA had no effect on transformation. When type R bacterial cells were mixed with material from heat-killed type S cells in the presence of proteinase (protease) to digest protein, the type R bacteria were still transformed into type S bacteria. Thus, digestion of protein had no effect on transformation. When type R bacterial cells were mixed with material from heat-killed type S cells in the presence of deoxyribonuclease (DNase) to digest DNA, the type R bacteria were not transformed into type S bacteria. Alfred Hershey and Martha Chase examined a bacteriophage named T2 that infects e. coli. T2 contain two molecular components: DNA and protein. T2 also contains other structures (a sheath, tail fibers, and a base plate) made of proteins. Bacteriophage components, which remain attached to the surface of the bacterium, can be separated from bacteriophage components that are injected into the cytoplasm of the E. coli cell using a kitchen blender. Bacteriophage proteins were radiolabeled with 35S and the bacteriophage DNA was radiolabeled with 32P. In one experiment, bacteriophage T2 proteins were labeled with 35S. In another experiment, bacteriophage T2 DNA was labeled with 32P. The radiolabeled bacteriophages were mixed in two separate reactions with E. coli cells to allow a bacteriophage

infection to proceed. The reactions were subjected to blending. During blending, the bacteriophage components attached to the surfaces of the E. coli cells were released. After blending, the bacteria were collected in a centrifuge. The bacteriophage heads, sheath, and tail fibers remain in the supernatant (liquid) after centrifugation. The E. coli cells and the genetic material of the bacteriophage are found in a pellet at the bottom of the centrifuge tube. After blending, the bacteria were collected in a centrifuge. The amount of radioactivity in the supernatant and pellet was calculated. Blending removed most of the 35S from the bacterial cells. However, most of the 32P remained within the host E. coli cells.Note that after the completion of the bacteriophage life cycle, the progeny bacteriophages contained 32P. Scientists reasoned that the genetic material of eukaryotes should be found within chromosomes because chromosomes are copied and distributed to daughter cells during mitosis and meiosis. Chromosomes contain both proteins and DNA; however, the DNA component is found exclusively in chromosomes (i.e. protein is found in the cell cytoplasm as well). In addition, a diploid cell, which contains twice as many chromosomes as a haploid cell, also contains roughly twice as much DNA as a haploid cell. No such correlation was observed when the protein content of haploid and diploid cells was compared. (UV light) is capable of causing mutations that can affect the phenotype of a cell. The wavelength of UV light that produces the highest frequency of mutations (260 nanometers) corresponds to the wavelength of UV light that is absorbed most strongly by DNA. On the other hand, the wavelength of UV light absorbed most strongly by proteins (280 nanometers) does not produce mutations. Recombinant DNA technology provided direct evidence for DNA, In this technique, a DNA sequence from a eukaryotic cell can be isolated and then introduced into a bacterial cell. This eukaryotic DNA sequence is then transcribed by the bacterial cell to make a mRNA. The mRNA is translated by the bacterial cell to make a protein. The resulting protein can change the phenotype of the bacterial cell. The introduced eukaryotic DNA sequence is also passed on to the progeny bacterial cells during bacterial cell division. As an example, recombinant DNA technology allows bacterial cells to produce the human insulin protein. The fact that introduced eukaryotic DNA can result in protein production, can alter the phenotype of a bacterial cell, and can be inherited provides strong evidence that DNA is the genetic material of eukaryotes. DNA and RNA molecules have four levels of structural complexity: Nucleotide, the basic subunits of nucleic acid molecules. Nucleic acid strand, a chain of nucleotides covalently linked together. Double helix, Two nucleic acid strands of either DNA or RNA can hydrogen bond together to form a double helix structure. Chromosomes, DNA molecules associate with proteins to form prokaryotic and eukaryotic chromosomes....