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