Biology Genetic Engineering Gel Electrophoresis

Biology Genetic
Gel Electrophoresis
Juliana Machado
Isabella Rojas
Gabriel Felipe Galvis
Genetic Engineering
Also called genetic modification.
Is the human manipulation of an organisms genome
(hereditary information of the organism) using modern
DNA technology.
It involves the introduction of DNA or synthetic genes
into the organism.
Humans have altered the genomes of species for thousands of years
through artificial methods. Genetic engineering considered the direct
manipulation of DNA by humans has only existed in 1970s.
Paul Berg created the firsr recombinant ( DNA sequences that result
from the use of laboratory methods). By combining the monkey virus
SV40 with lambda phage (another virus consisting of a head)
 Herbert and Stanley Cohen created the first transgenic
organism by inserting antibiotic resistance genes into
the plasmid of an E. Coli bacterium.
 Rudolf
Jaenisch created a transgenic mouse by
introducing DNA into its embryo, making it the first
transgenic animal.
 In 1976,
Genentech, the first engineering company
was founded by Herbert Boyer and Robert Swanson.
Genetic engineering has applications in medicine,
research, industry and agriculture.
Medicine: Genetic engineering has been used to produce
insulin, human growth hormones. Also it is used to create
animal models which are non-human animals, used
during the research and investigation of human diseases.
Genetically modified mice are the most common
genetically engineered animal model.
 Research: Genetic engineering is an important tool for
natural scientists. Genes and other genetic information
from a wide range of organisms and information are
transformed into bacteria for storage and
modification, creating genetically modified bacteria in
the process. Also organisms are genetically engineered
to discover the functions of certain genes. This could
be the effect on the phenotype of the organism, where
the gene is expressed or what other genes it interacts
 Industry: By engineering genes it is possible to create a
biological factory that can produce proteins and
enzymes. Bacteria and yeast have been used to
produce medicines such as insulin, human growth and
vaccines ( biological preparation that improves
immunity to a particular disease).
 Agriculture: Genetic engineering is used in the
creation of genetically food. Genetically modified
organisms have had specific changes introduced into
their DNA by genetic engineering techniques. These
techniques are much more precise, an example is
mutagenesis (mutation breeding) where an organism is
exposed to radiation or chemicals to create a nonspecific but stable change. Other techniques by which
humans modify organisms include: selective breeding,
plant breeding and animal breeding. Since genetically
modified food has been introduced into supermarkets,
there has been much controversy.
What is Gel
When DNA manipulation began, DNA fragments were
separated by gravity. In the 1970s, the powerful tool of
DNA electrophoresis was developed.
Gel electrophoresis in chemistry: Is a method used to
separate proteins by charge and size
Gel electrophoresis in biochemistry: In molecular
biology it is used to separate DNA and RNA fragments
by length, to estimate the size of DNA and RNA.
Electricity effects on
Nucleic acids molecules are separated by using a
electric field to move the negatively charged molecules
through an agarose matrix
 We need to take into account that shorter molecules
move faster and migrate longer than longer ones
because shorter molecules migrate more easily through
the pores of the gel. This process is called sieving. is a
simple and convenient technique of separating particles
of different size
 In the case of proteins they are separated by charge in
agarose becuase the pores of the gel are too large to
sieve proteins Also electrophoresis can be used in the
separation of nanoparticles.
 Agarose is a polysacharide obtained from agar that is
used for a variety of science applications, specially in
gel electrophoresis.
 Agarose it is used in the matrix, which plays a vital
role in this separation.
Agarose used as a
gel to be incluided
in the matrix.
How does gel electrophoresis
DNA is extracted from cells or
obtained using PCR (polymerase chain
reaction), they are cut into many fragments
of different lenghts with restriction
enzymes (enzyme that cuts DNA).
-DNA fragments are loaded into the wells of an agarose gel and placed
in an electrophoresis buffer filled tank. This gel which is similar to
gelatin is formed for the DNA fragments to be placed in here.
-This gel is placed in the matrix and contains electrolytes, so that an
electric current conducted.
-Positive and negative electrodes are connected to the opposite ends of
the gel- (electric field is applied).
-The negatively charged DNA fragments are drawn towards the positive
 The agar gel is highly porous
 Shortest DNA fragments are able to move quickly
through the pores.
 Larger DNA fragments move very slowly because it is
more difficult for them to pass through the pores.
Applications of Gel
 Estimation of the size of DNA molecules. Example:
restriction enzyme (enzyme that cuts DNA) also
called restriction mapping of cloned DNA.
 Analysis of PCR(polymerase chain reaction) products
is a scientific technique in molecular biology to
amplify or increase a single or few copies of a piece of
DNA across several orders, generating thousands or
millions of copies of a particular DNA sequence.
8 PCR tubes, each containing a
reaction mixture
What is DNA profiling?
 DNA profiling also called DNA fingerprinting, DNA
testing, is a technique use by forensic scientists to
distinguish between individuals of the same species
using samples of their DNA.
 Although the majority of our DNA is the same, there
are short pieces called microsatellites . These repeat
many times in a persons DNA. This is the pattern of
repeats which is different in every individual.
 Knowing these microsatellites, DNA sequences are the
basis for the DNA profiling.
Stages of DNA profiling
 STEP 1: Cells are broken down to release DNA. If a
small amount of DNA is available, the amount can be
increased or amplified by using polymerase chain
reaction (PCR).
 STEP 2: The DNA is cut into fragments
restrictions enzymes as I explained before. Each
restriction enzyme cuts DNA at a specific base
 The sections of DNA which are cut are called
restriction fragments.
 STEP 3: In DNA profiling the gel electrophoresis is
involved Fragments are separated on the basis by using a
process called gel electrophoresis.
DNA fragments are inserted in the wells and a electric
current is developed. As I explained before in gel
 DNA is negatively charged so it is attracted to the positive
part of the gel.
 DNA is separated on the basis of size.
 A radioactive is added which combines with the DNA
fragments to produce a image, that contains the copies of
DNA bands.
 STEP 4: The pattern of the fragment is analyzed.
 DNA profiling is used to solve medical problems.
 Biological uses for DNA profiling:
Body tissue cells

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