Gene Cloning
Definition
To clone a gene means to cut it out of its
original place in the host DNA and ligate it
into a suitable "vector" where multiple
copies of it can be quickly
reproduced.
How it works
1. Must attain a sufficient amount of the
DNA to be cloned.
2. Then attain a vector.
A vector is a piece of DNA that replicates in
bacterium.
How it works
3. Use of application restriction to cut the
DNA.
Next we use restriction enzymes to cut out the
gene we want from the amplified product. We
use the same enzymes to cut the vector so that
the ends will be compatible. This means that if
we use a "sticky ends" restriction enzyme, then
the DNA sequences of the trailing bits will be
compatible and will want to stick to each other.
This makes it much easier to do. If we can't find
a suitable site for a sticky end restriction enzyme
then we can use a "blunt
-
ended" one, which is
a bit harder to make work.
How it works
4. Ligation
Once both the vector and the target DNA
have been cut we mix them together and
add the ligase enzyme. This enzyme ligates
(connects) the
phosphodiester
backbone
acting as a glue to stick the ends together.
How it works
5. Transform bacteria
This just means add the DNA back into a
bacteria. There are a number of different
ways of doing this, but most of them involve
making the bacterial cell membrane
temporarily porous so that it can take up
the liquid containing the DNA mix. Then you
let the cells recover and grow them up as
usual.
How it works
6. Screening for 'positives'; Those bacteria
that have the cloned DNA in them.
Sometimes you don't get what you want!
For instance, a sometimes time the vector
will just stick back to itself, or stick to another
vector without having any target DNA in it.
So you have to have a mechanism for
picking out the ones where the target DNA
has gone into the vector.
Benefits
Combat diseases
Creates organs for transplants
Improve taste/quality of food
Repopulate endangered animals
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%20Cloning%20a%20Gene
Polymerase
Chain
Reactions
Sarah Schwartz, Haley
Kaufman,
Audine
Crosse
Definition/Overview
Polymerase Chain Reactions
:
A
mplifies a
single piece of DNA across several orders of
magnitude. The end result is the creation of
thousands to millions of copies of a
particular DNA sequence.
So how many steps are there?
It is a 3
-
step process (cycle) that is
repeated a specified number of times.
One PCR cycle consists of the following
steps:
1.
Denaturation
2.
Annealing
3.
Extension
The Steps
Denaturation
: Heat
separates double
-
stranded DNA into two
single strands.
Annealing
: Cool to
allow primers to form
hydrogen bonds with
ends of target
sequence.
Extension
: DNA
polymerase adds
nucleotides to the 3’
end of each primer.
So what happens next?
The process continuously repeats, forming
new molecules. For example, in cycle 1, 2
molecules are yielded. In cycle 2, 4
molecules are yielded. In cycle 3, 8
molecules are yielded.
Gel Electrophoresis
Used to
separate a mixed
population of DNA and RNA
fragments by
length, and to
separate proteins by
charge
Nucleic acid molecules are
separated by applying an electric
field to move the negatively
charged molecules through an
agarose matrix.
Sieving
–
Shorter
molecules move faster
and migrate farther than longer ones
because shorter molecules migrate
more easily through the pores of the
gel
.
Proteins are separated by charge in
agarose
Reading Gel Electrophoresis
Results
1
.) By looking at the migration of the
DNA molecular weight standards, you
can tell that the migration of DNA
through an
agarose
gel is not linear
with respect to
size.
If you graphed the distance
traveled vs. the molecular
weight of the fragment, you
would see that there is a
logarithmic relationship
Typically the samples are ran against a DNA ladder
which has DNA fragments of other known DNA sizes
so you can tell the size difference of the piece of
DNA in your sample.
The bands at the bottom are pieces of shorter DNA
and the faster they move through the gel. Towards
the top is the larger pieces of DNA and the slower
they move through the gel.
Gel
Electrophresis
Types of Gel
Agarose
-
Used to separate DNA fragments ranging from
50 base pair to several megabases. The distance between
DNA bands of a given length is determined by the percent
agarose in the gel. Gel setting is a physical, rather than
chemical change. Agarose gels do not have a uniform
pore size. Samples are also easily recovered.
Polyacrylamide
-
used for separating proteins ranging in size
from 5 to 2,000
kDa
due to the uniform pore size. Pore size is
controlled by controlling the concentrations of acrylamide
and
bis
-
acrylamide powder used in creating a gel.
Starch
-
Partially
hydrolysed
potato starch which is non
-
toxic. The gels are slightly more opaque. Non
-
denatured
proteins can be separated according to charge and size.
They are
visualised
using
Napthal
Black or
Amido
Black
staining. Typical starch gel concentrations are 5% to 10
%
Gel Electrophoresis
Gel Conditions
Denaturing
-
A denaturing gel is a type of
electrophoresis in which the native structure of
macromolecules that are run within the gel is not
maintained. In contrast to native, quaternary
structure cannot be investigated using this method.
Native
-
Native gel electrophoresis is an
electrophoretic separation method typically used in
proteomics and
metallomics
. Unlike denaturing gel,
native gel electrophoresis does not use a charged
denaturing agent
.
DNA Sequencing
By: Catherine Scott
Elizabeth
Dreisbach
Fallon
Prigmore
What is it?
Any process used to map out the sequence of the
nucleotides that comprise a strand of DNA
Any technology that is used to determine the order of
the four bases in a sequence of DNA: adenine, guanine,
cytosine, and thymine.
Adenine is paired with Thymine
Guanine is paired with Cytosine
DNA sequencing is a newer technology; It has been
known since the invention of the microscope that some
central part of the human cell has as its core some small
piece of information holding matter that probably
contains the blueprint of how each cell in your body is
form.
DNA Sequencing
Two common methods available are:
Maxam
-
Gilbert technique
which uses
chemicals to cleave DNA into fragments
at specific bases
The
Sanger Technique
uses DNA
polymerase to make DNA chains in the
presence of di
-
deoxynucleotides
to stop
the chain randomly as it grows.
This technique is more commonly used.
In both cases the DNA fragments are
separated according to length.
The Human Genome Project
The advent of DNA sequencing has
significantly accelerated biological
research and discovery.
It was devoted to developing and
bettering tools to make gene hunts faster,
cheaper, and more practical.
Produced the first complete sequences of
individual genome sequences.
As of 2012, thousands of human genomes
have been completely sequenced, and
many more have been mapped at lower
levels of resolution.
DNA structure and
sequencing
Animal
Cloning
Fun Facts
On July 5, 1996 Dolly the
sheep as the first successful
mammal cloned
The clones are only
genetically identical, they
can have different
personalities and physical
characteristics and
contains different
mitochondrial DNA
material
High failure rate
The animal cloning process is
called 'somatic cell nuclear
transfer'
Process of Reproductive
Cloning
Transfer of already made DNA into an
egg to make a genetically identical
organism
Steps
Nuclear Transfer
Stimulate Cell Division
Embryo Transplant in Host
Nucleus Transfer: transfers genetic
information from the animal cell to the egg
which has been stripped of its nucleus
Stimulated Cell Division: then the egg is
stimulated to divide by treatment with
chemicals or electric current
Totipotent: ability to create an entire
organism through cell division
Embryo Transplant in Host:
the cell begins dividing into a multi
-
cellular
embryo
It is planted into the uterus of a female host
The rest of the development occurs just like a
normal organism
Transformation
Maddie
, Meaghan, Al and
Gabriella
Definition
The insertion of a foreign gene into an
organism in order to change that
organism's expressed trait.
Natural Competence
The ability for cells to take up extracellular
genetic information
This state can occur as a result of
starvation or cell density
Plasmids
Circular molecules of genetic information
which replicate independently of bacterial
chromosomal DNA
Restriction Enzymes
Enzymes that protect the bacterial cell by
cutting up the foreign DNA from other
organisms or phages.
Glowing Tobacco
Bioluminescent gene from fireflies
uptaken
by tobacco
stem cells
Biotech
Applications
Addie, Kendall, Julia, Tai
Gene Cloning
Can be used to manipulate and analyze
DNA
In genetic engineering, bacterial
restriction enzyme are used to cut
molecules within short nucleotide
sequences, yielding a set of DNA
fragments
Cloning
vecotrs
include plasmids and bacterial artificial chromosomes.
Recombinant
plasminds
are returned to host cells, each of which divides
To form a clone of cells. Collections of clones are stored as genomic or
Complementary DNA libraries. Libraries can be screened for a gene of interest.
Using nucleic acid hybridization.
DNA Technology
DNA fragments separated by gel
electrophoresis
Short DNA fragments sequenced by
dideoxy
chain termination method
In humans, genome
-
wide association
studies use single nucleotide
polymorphisms as genetic markers for
alleles associated with particular
conditions
Stem Cell Research
Certain
embyronic
stem or adult stem cells
from animal embryos or adult tissues can
reproduce and differentiate in vitro as well as
in vivo, offering potential for medical use.
ES cells are pluripotent but difficult to acquire
Induced pluripotent cells resemble ES cells
and can be generated by reprogramming
differentiated cells. They hold promise for
medical research and
regenerative
medicine.
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