DNA Structure
(deoxyribonucleic Acid)
Biology
Chp. 9
DNA
DNA Structure
 Double
Helix – 2 twisted strands of DNA
 Partially
unwound double helix so you can see
components
DNA composed of
nucleotides
3 parts
1. Sugar (deoxyribose)
2. Phosphate group
3. Nitrogenous bases
1.
2.
A–T
C-G
Base Pairing Rules
 A always pairs with T
 C always pairs with G
 A is complimentary to T and
 C is complimentary to G
One strand of DNA
determines the other
2
2
1
3
1
Nitrogenous
base
3
DNA Structure
A
5 C sugar and
a phosphate
group form the
backbone
DNA Structure
 Nitrogenous
bases
A,
T, C, & G
make up the
rungs on the
ladder
DNA Structure
3D Video Clip from University of
Utah (Click next 4 times)
3 methods to analyze DNA

RFLP- Restriction Fragment Length Polymorphism
 Restriction
enzymes cut DNA up
 Not best method because we need a lot of DNA

PCR – Polymerase Chain Reaction
 Polymerase
– enzyme that replicates (makes more)
DNA

STR – Short Tandem Repeats
 Specific
sequences of DNA fragments that are
repeated at a particular site on a chromosome
Replication Technology

Mitochondrial DNA- from mom only


good for hair, teeth, and bone
PCRPerhaps the most successful technology to ever
emerge from LIFE SCIENCE!!!
 Many Uses

 Forensics
blood, convict, exonerate false accusations
 Agriculture,

Vet., Medicine, Envi. Sci.,
Microorganisms, viruses, parasites…