Week 2: DNA and Transformation & Proteins
Week 2: DNA and Transformation & Proteins Bio 107
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This 3 page Class Notes was uploaded by Rachel Johnson on Monday September 14, 2015. The Class Notes belongs to Bio 107 at Washington State University taught by William Davis in Summer 2015. Since its upload, it has received 41 views. For similar materials see Biology in Biology at Washington State University.
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Date Created: 09/14/15
DNA and Transformation Search for Genetic Material 0 v Scientists knew chromosomes were made of protein and DNA but didn t know which was responsible for inheritance Genes a region of DNA that encodes the traits expressed in an organism Chromosomes chemical structures that contain genes the molecules passed from parent to offspring during reproduction Griffith s Experiment 0 v Studied bacterial strains that cause pneumonia the bacteria pneumococcus S strain Pathogenic virulent Carbohydrate coat smooth cell covering R strain Non pathogenic non virulent No coat rough cell covering v Experiment Results S strain killed mouse R strain mouse lived Heat Killed S strain mouse lived Heat Killed S strain and live R strain killed mouse 0 v Conclusion Something in the heat killed S strain converted the live R strain to a pathogenic strain A transforming substance Avery s Experiment 339 Experiment conducted by Avery MacLeod and McCarty in 1944 339 Realized Griffith never identified the chemical nature of the transforming substance v Technology had progressed to where now enzymes were available that could selectively hydrolyze different types of molecules Goal discover the nature of the transforming substance in bacteria Hypothesis there is a single agent and using enzymes can establish which molecule is responsible 339 Experiment Started with S strain bacteria Heat killed and broke apart to generate a filtrate Treated five identical batches of the filtrate with one of the five enzymes RNase breaks down RNA DNase breaks down DNA Protease breaks down protein Lipase breaks down lipids Carboase breaks down carbohydrates compleX sugars Added treated S strain to living R strain If the transforming agent was still present then the R cells wouldbe converted to S cells Conclusion DNA was the transforming substance Modern Understanding of Transformation 339 Transformation is related to the uptake of DNA from the environment 339 A healthy bacterial cell has a single circular chromosome a plasmid When the cell is stressed the chromosomal DNA is broken into small pieces Released DNA can be absorbed and used by other cells