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Genetics Notes test 1 - Genetics Lecture 1 Phenotype...

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Genetics Lecture 1 Phenotype – observable trait Genetics – Heredity and traits in an individual as well Gene – unit of heredity 1. Correlation between particular gene and particular trait (phenotype) 2. Replication is possible/necessary 3. Variability can change via mutation 4. Stability (relative) Cellular Organisms: Eukaryotes vs Prokaryotes Eukaryotes – have nucleus, linear chromosomes, and both nucleic acids and proteins The acellular equivalent of a euk. are eukaryote viruses Prokaryotes – no nucleus, circular chromosomes (plastids), only nucleic acids The acellular equivalent of a prok. are cyanobacteria and BG algae What is the Genetic Material 1913 Boveri: # of chromosomes in Drosiphilia phenotype 1928 Griffith: Streptococcus pneumonia – had smooth colonies on Petri dishes that contained a smooth mucopolysaccharide coat. They were virulent and caused disease. Lecture 2 – Continued. S. pneumonia – coat is a mucopolysaccharide coat. Two kinds, both smooth and rough colonies in experiment. Smooth: virulent (can kill) Rough: avirulent (harmless) Griffith grew smooth colonies which made more smooth colonies and occasionally a rough colony would come up. If the colony progeny went from smooth to rough and then back to smooth, it was termed “revertant”, or reverted back to original phenotype. Original phenotype = wild phenotype SI SII SIII. SI can potentially produce RI, but cannot produce RII. Only SII can produce RII progeny. Mutant form = rough form (RII) Experiment: I. RII (live) + SIII (heat killed) = dead mouse II. RII (live) only = live mouse III. SIII (heat killed) only = live mouse Found SIII bacteria in dead mouse…how? Something in the RII bacteria allowed SIII to be reproduced.
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1944 Avery McClead McCarty Agglutination Assay Anti-RII antibody clumps out of solution Put live RII bacteria with purified components of SIII bacteria such as just the nucleic acids or proteins etc. They saw what precipitated out and figured out what was in there and what was still in solution after anti RII antibodies were added Nucleic acid is only component that caused clumps meaning live SIII offspring therefore nucleic acid is the genetic material for bacteria – science said so what? 1953 Hershey and Chase Bacteriophage T2 Nucleic acid in head (which is made of protein coat – capsid) Tail fibers are made of protein as well Attach to bacteria cells to reproduce by injecting nucleic acids 35 Sulfur – radioactive- only found in proteins 32 Phosphorus – radioactive – only found in nucleic acids I. 35 S-phage (protein) + bacteria blender collect infected bacteria are they radioactive? Bacteria cells and phage progeny – bacteria cells were found not to be radioactive, and the phage progeny was not either. Protein is ruled out as the genetic material.
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