BOLOGY 107 Lecture 25 Outline of Last Lecture I Chromosomal Basis of Inheritance a Sex linked traits b Gene linkage c Recombination frequency d Errors in chromosomal inheritance Outline of Current Lecture II Corrections to Notes on X linked Gene Pedigree III Non Mendelian Genetics a Maternal imprinting b Genetic Material c DNA structure Current Lecture Corrections to Notes on X linked Gene Pedigree 1 When stating that an affected male cannot come from an affected male and that the descendents from a non affected male are not affected are only considering that the non affected male cannot pass the affected gene as they do not have it Non Mendelian Genetics 2 Maternal imprinting a Gene can be methylated in the egg or sperm b Methylated gene is replicated during mitosis after fertilization c Modifies the resulting phenotype i Heterozygote will display a different phenotype depending on if the methylated gene comes from the mother or father 1 Due to X inactivation 3 Genetic Material a Found by Morgan i Genetic material found in a linear array along chromosomes a Identified as proteins and DNA not sure which carried genes b Griffith experiment i Identified two bacterial strains one that causes pneumonia and one that doesn t 1 S strain smooth coat pathogenic These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 2 R strain rough coat non pathogenic ii Living cells of each strain were injected into mice as control 1 S strain mice died R strain mice lived iii Tested heat killed S strain injected into mice mice lived iv Mixed heat killed S strain and living R strain together and injected into mice mice died 1 Extracted living S strain from the mouse change in R strain c Avery experiment i Followed Griffith s experiment idea ii Altered by stripping away proteins lipids carbohydrates and RNA from the heat killed S strain cells to only leave DNA iii Mixed DNA with living R cells and injected into mice mice died 1 There was question as to if only DNA was left d Hershey Chase experiment i Used distinctive radioactive labeling of protein and DNA in bacteriophages 1 Bacteriophages are viruses that infect bacteria They are made of DNA and proteins and transfer their genetic material into the cell while leaving a coat attached to the cell ii Labeled proteins in bacteriophage one color while labeled DNA a separate color a After allowing the virus to infect the cells the cells were ran through a blender to detach cells and virus coats b Mixture was ran in a centrifuge to separate cells and coats 2 Viral coats were found as the supernatant and DNA was found in the cells iii Concluded that DNA was the genetic material 4 DNA structure a Linear polymer of nucleotides i Sugar backbone ii 4 possible nitrogenous bases 1 Thymine T adenine A cytosine C guanine G b Contributing insights i Edwin Chargaff 1 Studied DNA composition in many species 2 Chargaff s rules a The base composition of DNA As Ts Gs and Cs differs from species to species b A always equals T G C ii Rosalind Franklin 1 Used X ray diffraction a DNA is helical b DNA is double stranded c Phosphates are on outside d DNA has a minor repeat and a major repeat individual bases and helical turns e Approximate measurements iii Watson and Crick 1 Made first models of DNA and tried to fit Chargaff s and Franklin s results
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