AP BIOLOGYDNA History & Structure

Nucleic Acid Structure

Complimentary Base Pairing

Frederick Griffith

FREDERICK GRIFFITH EXPERIMENT

Living S cells(control)

Living R cells(control)

Heat-killedS cells (control)

Mixture of heat-killedS cells and livingR cells

Mouse dies

Living S cellsare found in blood sample

Mouse healthy Mouse healthy Mouse dies

RESULTS

Oswald Avery

Avery and group identified the transforming substance was DNA. His colleagues were McCarty and MacLeod.

Alfred Hershey & Martha Chase

Bacteriophage injecting its DNA into a bacterial cell

Electron Microscope View

Hershey – Chase Experiment

Erwin Chargaff

CHARGAFF’S RULE

Adenine = Thymine (DNA) or Uracil (RNA)&Guanine = CytosineIf you know the % composition of 1, you can find the % composition of the other 3.

Rosalind Franklin

DNA from a top view

DNA from a side view

James Watson & Francis Crick with their DNA model

See the HYDROGEN bonds?