AP Biology Chapter 13: Meiosis and Sexual Reproduction
Chapter 13 Guided Reading Assignment 1. Explain Griffith’s experiment and the concept of transformation in detail.2. What did Avery, MacLeod and McCarty contribute to this line of investigation?3. What is a bacteriophage?4.Label the diagram below and explain the Hershey Chase experiment.5. How did Chargraff’s work contribute to understanding the structure of DNA?6. Why was Rosalind’s Franklin’s work essential to the understanding of the structure of DNA?Griﬃth had two strains of the bacterium, a pathogenic one and a nonpathogenic strain. He was surprised to Fnd that when he killed the pathogenic bacteria with heat and then mixed the cell remains with living bacteria of the nonpathogenic strain, some of the living cells became pathogenic. Avery puriFed various types of molecules from the heat-killed bacteria, then tried to transform nonpathogenic bacteria with each type. Only DNA worked. ±inally, in 1944, Avery and his colleagues McCarty and MacLeod announced that the transforming interest was DNA.A bacteriophage is a virus that infects bacteria, and only infects a speciFc host cell.He reported that DNA composition varies from one species to another, which accounts for the genetic variation found between diferent species. He also found a peculiar regularity in the ratios of nucleotide bases within a single species. The DNA composition changes from species to species, but it is consistent within the same species.