BIOL 1411 1st Edition Lecture 20Outline of Last Lecture I. More Geneticsa. Genetic Mapsb. Sex Chromosomesc. X-linkedd. Probabilities Outline of Current Lecture II. DNA Structurea. Transformationb. Genetic Materialc. Structure Lecture- Genetic Transformationo Frederick Griffith determined that a transforming principle from dead cells of Streptococcus pneumonia produced a heritable change in another straino Evidence the DNA is responsible for transformation To identify the transforming principle- Oswald Avery treated samples to destroy different molecules; if DNA was destroyed, the transforming activity was lost- There was no loss of the ability to transform with destruction of proteins, carbohydrates, or lipids o Evidence the DNA is the genetic material Hershey-Chase experiment- Used bacteriophage T2 virus to determine whether DNA, or protein, is the genetic material- Bacteriophage proteins were labeled with 35 S; the DNA was labeled with 32P - DNA is the Genetic Materialo Genetic transformation of eukaryotic cells and organisms, transfection, can be demonstratedo A genetic mark- a gene the confers an observable phenotype- is used to measuretransfectiono Any cell can be transfected, even an egg cell –result in a transgenic organism 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.- DNA Structureo Chemical composition of Deoxyribonucleic acid (DNA)o DNA is a polymer of nucleotides 2’ deoxyribos, a phosphate group, and a nitrogen-containing baseo The bases form the differences: Purines: A, G Pyrimidines: C, T Chargaff’s Rule: A +T , G + C- Evidence of the structure of DNAo Franklin’s x-ray crystallography convinced Watson and Crick the molecule was helicalo Over evidence suggested there were two polynucleotide chains that ran in opposite directions – antiparallelo Chargaff’s findings o In 1953, Watson and Crick established the general structure of DNA- Base Pairing in DNA is Complementary o Sugar-phosphate backbone is antiparallel: 5’3’ strand paired with 3’ 5’ strand- Antiparallel strands: Polarity of strand is determined by the sugar-phosphate bonds- Phosphate groups connect to the 3’ C of one sugar, and the 5’ C of the next sugar- The two chain ends differ: one is a free 5’ phosphate group- the 5’ end; the other is a free 3’ hydroxyl group- the 3’ end- By convention, DNA sequence is written 5’ to 3’ as a single
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