TAILIEUCHUNG - Lecture Molecular biology: Chapter 2 - Robert F. Weaver

Chapter 2 - The molecular nature of genes. Before we begin to study in detail the structure and activities of genes, and the experimental evidence underlying those concepts, we need a fuller outline of the adventure that lies before us. Thus, in this chapter and in chapter 3, we will fl esh out the brief history of molecular biology presented in chapter 1. In this chapter we will begin this task by considering the behavior of genes as molecules. | Molecular Biology Fourth Edition Chapter 2 The Molecular Nature of Genes Lecture PowerPoint to accompany Robert F. Weaver Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Nature of Genetic Material Historical Background Miescher isolated nuclei from pus (white blood cells) in 1869 Found a novel phosphorus-bearing substance = nuclein Nuclein is mostly chromatin, a complex of DNA and chromosomal proteins End of 19th century – DNA and RNA separated from proteins Levene, Jacobs, et al. characterized basic composition of DNA and RNA 2- Transformation in Bacteria Key experiments done by Frederick Griffith in 1928 Observed change in Streptococcus pneumoniae — from virulent (S) smooth colonies where bacterial had capsules, to avirulent (R) rough colonies without capsules Heat-killed virulent colonies could transform avirulent colonies to virulent ones 2- Outline of Griffith’s Transformation Experiments 2- DNA: The Transforming .

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