DNA Structure
Forensics
Chp. 12
DNA Analysis
DNA Structure
A gene is a long section of a DNA
molecule whose sequence of building
blocks specifies the sequence of amino
acids in a particular protein.
 Protein- fundamental component of living
cells
 Enzymes
Hemoglobin
 Hormones
Insulin

 Antibodies
How does DNA work
DNA (nucleic acid) 
 Amino Acids 
 Protein  Do a job (perform a function)
 Analogy to remember what’s going on, build
a house

 DNA
is the blue prints (instructions)
 Amino Acids are the lumber
 Proteins are the house…
DNA Structure
 View
from the side - Helix
 Partially
unwound double helix so you can see
components
Views from the top
Model
X-Ray
Photo-51
 DNA
composed of
nucleotides
 Sugar
(deoxyribose)
 Phosphate group
 Nitrogenous bases
A-T
C-G

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
Complimentary Base Pairing
Bases held together
with Hydrogen
bonds
 Guanine pairs with
Cytosine

 Triple

bond
Adenine pairs with
Thymine
 Double
bond
DNA Structure
3D Video Clip (Click next 4 times)
3 methods to analyze DNA

RFLP- Restriction Fragment Lengths
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, Env. Sci.,
Microorganisms, viruses, parasites…