PCB 3063 Lecture Notes - Lecture 79: Chromatin, Genetic Engineering, Pyrimidine
27 Mar 2016
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Scientists believed that it was protein was the genetic material, this was because: protein"s complexity could account for biodiversity, dna and rna are chemically very simple, chromatin: mixture of dna and protein. In the 20th century, scientists discovered nucleotides: nucleotides: phosphate group + sugar + base. Hypotheses on nucleotides: levine"s hypothesis or the tetranucleotide hypothesis: each nucleotide unit had four types of basis. Levine"s hypothesis was close, but incorrect: chargaff"s rules: bases in nucleotides vary in concentration. The four bases were adenine, thymine, cytosine, and guanine. Adenine = thymine and cytosine = guanine (concentrations) Chargaff also discovered that the ratio between the bases that are not complimentary, added, equate to one (a+g)/(c+t) = 1. The following are more contributions to the dna puzzle . Griffiths: found that genetic material could be transferred between bacteria: transformation: bacterial process where bacterial cell uptakes genetic material. Avery, mcleod, & mccarty: found that dna, not protein, was the transforming substance.
