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Unformatted text preview: Chapter 16: The Molecular Basis of Inheritance DNA Substance of inheritance Located on chromosomes polymer composed of monomers called nucleotides Each nucleotide contains: 1 phosphate group 2 pentose sugar deoxyribose 3 nitrogenous base . Huge challenge to: 1) determine substance of inheritance 2) its 3d molecular structure Know in ~1950: Hereditary material on chromosomes Chromosomes composed of protein and DNA Most thought proteins contained the genetic material (more diverse molecules) Circumstantial evidence to support DNA as the hereditary material in eukaryotes: 1) cell doubles its DNA prior to mitosis(S phase) 2) During mitosis, double DNA is equally divided into daughter cells 3)Diploid cells have 2X DNA as haploid cells 4) Erwin Chargaffs Data Erwin Chargaff Compared # and ratio of nitrogenous bases in many eukaryotes Used paper chromatography (separates bases based on density) Erwin Chargaff: Results DNA composition was species-specific amount and ratio of nitrogenous bases varies between species This creates molecular diversity!!!!...
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