8.1, 8.2, 8.3 Chapter 8 DNA

DNA Deoxyribonucleic Acid How Did we Discover DNA?

Transformation 1928 Griffith with mice One disease bacteria transformed the other harmless bacteria into a disease bacteria

R S

Is the genetic material made of DNA or protein Hershey-Chase Experiment- (1952) Studied viruses known as bacteriophages Is the genetic material made of DNA or protein

DNA made of monomers of nucleotides Nucleotides consist of 3 parts 5-carbon sugar deoxyribose Phosphate group Nitrogen base

Chargaff’s Rule A=T C=G Adenine bonds with Thymine Cytosine bonds with Guanine Nitrogen bases are held together by hydrogen bonds A=T C=G

X-Ray evidence- 1950’s Rosalind Franklin used X-ray diffraction to study structure of DNA. Concluded structure was coiled like a spring (double helix)

DNA is a double helix two complementary strands Strands consist of : Sugar phosphate backbone Nitrogen base rungs

DNA unzips- hydrogen bonds are broken Each parent strand serves as a template to form new complementary strand DNA polymerase- adds new nucleotide by base pairing rule. DNA polymerase proofreads each new DNA strand and repairs errors, unchecked error = mutation In prokaryotic cells replication is in 1 region In Eukaryotic cells it is in many regions

When DNA has completed replication there are two double strands Each strand contains one side of the parent strand plus a new complementary strand