YEN CHIH TSAI - CH16 RG The Molecular Basis of Inheritance.docx - Chapter 16 The Molecular Basis of Inheritance James Tsai Chapter 16 The Molecular

YEN CHIH TSAI - CH16 RG The Molecular Basis of Inheritance.docx

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Chapter 16: The Molecular Basis of Inheritance James Tsai Chapter 16: The Molecular Basis of Inheritance Genetic information provides for continuity of life. The double-stranded structure of DNA provides a simple and elegant solution for the transmission of inheritance information to the nest generation. This chapter will guide your study of DNA—how it was determined to be genetic material, its structure, and how it is faithfully duplicated. Concept 16:1 DNA is the genetic material 1. What are the two chemical components of chromosomes? DNA and protein 2. Why did researchers originally think that protein was the genetic material? Until the 1940s, biochemists thought protein was the genetic material, as they had identified proteins as a class of macromolecules with great heterogeneity and specificity of function, essential requirements for hereditary material. Moreover, little was known about nucleic acids, whose physical and chemical properties seemed far too uniform to account for the multitude of specific inherited traits exhibited by every organism. The role of DNA in heredity was first worked out while studying bacteria and the viruses that infect them, which are far simpler than pea plants, fruit flies, or humans. 3. Distinguish between the virulent and nonvirulent strains of Streptococcus pneumoniae studied by Frederick Griffith. Bacteria of the S (smooth) strain can cause pneumonia in mice; they are pathogenic because they have an outer capsule that protects them from an animal’s defense system. Bacteria of the R (rough) strain lack a capsule and are nonpathogenic. To test for the trait of pathogenicity, Griffith injected mice with the two strains. 4. Use this figure to summarize the experiment in which Griffith became aware that hereditary information could be transmitted between two organisms in an unusual manner. To test for pathogenicity, Griffith injected mice with pathogenic and nonpathogenic strains. Mice injected with the pathogenic control died while mice injected with nonpathogenic control remained healthy. Surprisingly, however, when the pathogenic bacteria were killed with heat and the cell remains then mixed with living cells of the nonpathogenic strain, some of the living 1
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Chapter 16: The Molecular Basis of Inheritance cells became pathogenic, also killing the mice. 5. Define transformation. Transformation is a change in genotype and phenotype due to the assimilation of external DNA by a cell. 6. What did Oswald Avery, McCarty, and MacLeod determine to be the transforming factor ? Avery broke open the heat-killed pathogenic bacteria and extracted the cellular contents. He treated each of three samples with an agent that inactivated DNA, RNA, or protein, and then tested the sample for its ability to transform live nonpathogenic bacteria. Only when DNA was allowed to remain active did transformation occur.
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  • DNA, Frederick Griffith, strand, DNA Damage

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