DNA – What is it & What does it do? Life Science 8 / Butler

The Structure of DNA DNA = __________________ Acid Genetic material found in the __________ of a cell Cells contain ________ of DNA in each cell In humans: DNA forms 23 homologous pair of _________ Chromosomes hold ____________: a section of DNA which codes for a specific _________ Humans have __________ of genes

DNA Structure shape = twisted ladder called a ______________________ Has 2 sides & rungs in between Sub units = _________________ Have 3 parts: ____________________: sugar made of 5 carbons linked together 2. ____________ group: phosphoric acid 3. 1 of the 4 types of ____________________

DNA Structure Nitrogen bases ____________ up the same way every time to make the __________ of the ladder (A)_______________+(T)_____________ (G)_____________ +(C)______________ Connected by a weak ______________ bond ________________ base pairs in human genome Sides of ladder: 2 parts Sugar (_______________) Phosphate (_____________________)

History of DNA By the 1950’s many facts were known about DNA Chargaff: discovered specific proportions of nitrogen bases (A-T) / (C-G) #s of each pair were not the same

History of DNA _______________________: scientist who had photographed DNA using Xrays to show the shape Nucleotide bases were stacked one on top of the other Her information became available to other scientists also researching DNA 1953: ____________& _____________ Proposed “double helix” model

Crick & Watson Model included: _____________ ladder structure Composed of ___________________ ____________________ bond together to form rungs 1962: won __________________ for model