Genetic Engineering Techniques Table


11 Δεκ 2012 (πριν από 4 χρόνια και 6 μήνες)

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Genetic Engineering Techniques
(p.613 to 618)

Name of the Genetic Tool

Purpose of the Genetic Tool

Process to Accomplish the Technique

Restriction Enzymes (DNA scissors)

specific part of a DNA molecule (ie. gene) is needed
. The part removed
from the DNA
is called a restriction fragment.
The desired portion of DNA
may be needed for Recombinant DNA, Amplification , or Electrophoresis

Restriction enzymes

mixed in with the DNA.
These enzymes maker very
specific cuts through the DNA. The enzyme can be used ov
er and over
again to get the same fragments.

Recombinant DNA

To take genes from a donor

organism and
place them in another organism

to make the organism with the new gene more desirable.

Restriction enzymes

are used to cut fragments of DNA out of the dono
fragments are spiced into the new organism

with splicing
enzymes. You saw how this worked in gene therapy if you visited the
online site.

DNA Amplification

(Method 1

use映f⁣lo湩ng vecto爩

increase the size of a sample of DNA

so you will h
ave enough DNA to
perform a proper test.

See p. 614 and Fig 18.9, p.615

The idea here is to
get the desired gene using DNA scissors and then
splice it into a bacterium
. The
bacterium multiplies

at a tremendous
rate. As it does the
desired gene gets multipl
ied as well
. The desirable
gene is spliced into a circular portion of DNA in the bacterium called a
. A plasmid is separate from the main chromosomal material of
the bacterium. The plasmid is
called the cloning vector

because it is the
part that rep
roduces the desired gene.

DNA Amplification

(Method 2


increase the size of a sample of DNA

so you will have enough DNA to
perform a proper test.

See Fig. 18.10, p. 615

This procedure is more efficient than Method 1
as the reaction proceeds
almost automatically with minimal effort on the part of the technician.
The steps are as follows:

1. the desired sample of DNA is placed in a solution with free
nucleotides and primers

2. the solution is heated and helix opens up
and base pairs split

3. the solution is cooled

4. heat resistant polymerase is added and DNA replication begins

5. the mixture is reheated and the process repeats itself

To get a proper appreciation of this process visit the following online

When you get there click on
, then
, then
, then
making copies of
, and finally
. Be sure to follow all the instructions so
you w
ill be successful.

Gel Electrophoresis

(see Fig. 18.11, p.617)

To separate DNA molecules according to their size and mass. This allows DNA
among organisms to be compared. This process is often used to identify

To get a better appreciation of th
e process visit the following online sites:

and then visit

and click on Electrophoresis.

A sample of DNA may have to be cut and amplified first.
The DNA is
then put into one end of a gel. Electric current is then sent thr
ough the
gel. The
DNA is towed through the gel by this current
. The DNA that
is smaller with less mass moves further than the larger more massive
This separates the DNA

and allows the technician to compare one
sample of DNA with another.
The pattern o
f separation in the gel is
called a DNA fingerprint.

DNA Sequencing

(See p. 616)

To determine the sequence of nucleotides in a DNA molecule

The nucleotide at the end of each fragment of DNA is tagged with a
radioactive or fluorescent marker. The fragment
s are run on a gel
Each fragment can be identified by the tag or marker.
The order of the fragments is noted. Each fragment is then studied
separately until its sequence is known. Then the entire sequence of
fragments is put together to
know the code on the entire chromosome.
The process depends on a modified version of PCR.