Genetic Engineering - tumascience.com

wirelessthrillBiotechnology

Dec 11, 2012 (4 years and 8 months ago)

209 views

Genetic Engineering


Restriction Endonucleases


-

enzymes that cut DNA at specific sequences

-

the discovery of these enzymes made genetic engineering


possible


E.g.

Eco R1 (from E coli) cuts the DNA sequence GAATTC







E.g.

Sma
1

makes the cut




How a

Gene is Cloned (DNA Amplification)

















Polymerase Chain Reaction


-

automated method of replicating DNA that allows researchers to


target and amplify a very specific sequence within a DNA


sample


-

relies on the action of DNA polymerase


-

DNA polymerase can only attach nucleotides to an existing


primer


-

researchers must first prepare and two primers (20 nucleotides)





















PCR requires a special machine called a thermonuclear to rapidly
heat and cool DNA



Sorting DNA F
ragments


Gel Electrophoresis is used to separate molecule
s

according to

their mass and electrical charge.



a.

Restriction enzymes cut


DNA into fragments


b.

A gel is formed with wells


and small amounts of DNA


are placed into the wells.


c.

The gel is

placed in a


buffer solution and an


electric field is set up so


that one end of the gel is


positive and the other is


negative.


d.

The negatively charged


DNA fragments travel


toward the positive end.


The smaller the fragment


the faster it mov
es


through the gel. Fragments that are the farthest from the well


are the smallest.


e.

Before the DNA is placed into the wells the DNA is

treated with


a dye that glows under UV light.








Analyzing DNA


The three processes described (restrictio
n enzymes, DNA
amplification and gel elec
trophoresis) can be used in a number of
ways to help researchers analyze and compare DNA samples.


For example;


-

DNA from a single hair follicle can be amplified using DNA


cloning or PCR to produce billions of c
opies of the sample DNA


-

a sample of the DNA can then be cut with restriction enzymes


and run on a gel


-

the pattern of bands can then be compared with the DNA


fingerprint of the suspect


-

in the same way DNA fingerprint evidence can be used to
solve


disputes over parentage