BIOL 1411 1st Edition Lecture 20 Outline of Last Lecture I More Genetics a Genetic Maps b Sex Chromosomes c X linked d Probabilities Outline of Current Lecture II DNA Structure a Transformation b Genetic Material c Structure Lecture Genetic Transformation o Frederick Griffith determined that a transforming principle from dead cells of Streptococcus pneumonia produced a heritable change in another strain o 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 Material o Genetic transformation of eukaryotic cells and organisms transfection can be demonstrated o A genetic mark a gene the confers an observable phenotype is used to measure transfection o 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 Structure o Chemical composition of Deoxyribonucleic acid DNA o DNA is a polymer of nucleotides 2 deoxyribos a phosphate group and a nitrogen containing base o The bases form the differences Purines A G Pyrimidines C T Chargaff s Rule A T G C Evidence of the structure of DNA o Franklin s x ray crystallography convinced Watson and Crick the molecule was helical o Over evidence suggested there were two polynucleotide chains that ran in opposite directions antiparallel o 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 strand
View Full Document
Unlocking...