Objective: Discuss DNA and base pairing 12.1
Griffith’s experiment: Injected disease causing bacteria into mice They died Injected harmless bac. Into mice They lived Injected heat-killed disease causing bac. Into mice Injected harmless bac. And heat-killed disease causing bac. Into mice
Transformation- when one strain of bacteria is changed into another strain What caused it to change? DNA
Avery: Tried to see if bacteria would still undergo transformation if only DNA was present Determined: DNA stores and transmits genetic info.
Hershey-Chase experiment: Further showed DNA is what stores/transmits genetic info (not protein) Used radioactive markers for the protein in one experiment and radioactive markers for the DNA in the other experiment.
What is DNA made of? Nucleotide- 5-carbon sugar, phosphate group and nitrogenous base Nitrogenous base Adenine, Guanine Cytosine, Thymine Purines Pyrimidines
Chargaff’s rule: same number of Adenines (A) as Thymines (T) same number of Guanine (G) and Cytosine (C) Base pairing: A pairs with T G pairs with C
Rosalind Franklin- used X-rays to determine shape of DNA. DNA had a cross shaped pattern Watson and Crick- used Franklin’s photos to come up with shape of DNA- double helix Double helix- twister ladder