Chapter 8 DNA
8.1, 8.2, 8.3
DNADNADeoxyribonucleic Acid
1928 Griffith with mice
One disease bacteria transformed the other harmless bacteria into a disease bacteria
SS RR
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
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 helixdouble helix two
complementary strands
Strands consist of :
Sugar phosphate backbone
Nitrogen base rungs
1. DNA unzips- hydrogen bonds are broken
2. Each parent strand serves as a template to form new complementary strand
3. DNA polymerase- adds new nucleotide by base pairing rule.
4. 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