Genetic Engineering Gene Therapy Cloning

groupmoujeanteaΒιοτεχνολογία

23 Οκτ 2013 (πριν από 3 χρόνια και 10 μήνες)

75 εμφανίσεις


1









04/30/2012


BIOL 116



















I.

Terms

II.

Inserting new genes into cells using a virus

III.

Examples of Genetic Engineering Applications

IV.

Concerns/Problems with Transgenic Organisms

V.

Gene therapy


VI.

Cloning
Genetic Engineering

Gene Therapy

Cloning

Primary Learning Objectives


Know the steps of normal viral infection and also how this usual process is used to
insert novel genes in organisms


Be

able to list applications and concerns about genetic engineering


Be able to describe an example of a human gene therapy procedure and concerns
about gene therapy


Be able to define the various types of cloning


Understand the steps in one type of higher
organism cloning



2




I. Terms



A
. Genetic Engineering:




Any manipulation of DNA



B. GM(O)s:


Genetically Modified (organism)
-

Usually refers to genetically engineered
organisms that are used as human consumables



D. Transgenic organism:





Organism that contains genes from another s
pecies




E. Biotechnology:




Biotechnology is an applied science, aimed at harnessing the natural



biological capabilities of microbial, plant and animal cells for the benefit



of people. Biotechnology couples scientific and engineering
1

principles



with commercial considerations to develop and improve products and



processes made from living systems.







1

Engineering
-
The application of mathematical and scientific principles to practical ends, as the design,
construction, and operation of economical and efficient structures, equipment,
and systems. Webster’s II
New College Dictionary.


3


II. Inserting new genes into cells using a virus






“Triggers”:

Viral genetic
material ‘jumps’
into the genetic
material of the
host.



To use the virus in genetic engineering
, the virus must be
altered first
:


1)

Viral Genes responsible for damaging the cell must be deleted.

2)

‘Desired’ ge
nes must be inserted into the viral genome.

3)

Viral genes that allow the virus to enter the cell and insert its DNA must

remain.



Virus attaches
to the surface of
the host cell

Virus enters the host cell

Under normal infection
conditions, the virus would
‘take over’ the cell and force
the cell t漠oa步 m潲e viruses
using the energy an搠nutrie湴
materials the cell nee摥搠f潲 its
潷n life 灲潣esses.


4

III. Examples of Genetic Engineering Applications


A. Pharmaceuticals


1. human insulin


2. human growth hormone



B. Crops: di
sease and herbicide resistance, slowed ripening, increased nutrition


1. BT toxin in corn


a) Isolated from the bacterium
Bacillus thuringiensis

b.) Insecticide activity against a variety of insects


2. Butril
-

resistant cotton


3. Flavr Savr tomato: ripen
ing gene inverted


4. Nutrition:

a. Soybeans with genes for increased lysine (amino acid)



IV. Concerns/Problems with Transgenic Organisms


A. Public fear


B. Public consent


C. Gene escape into natural populations


D. Germ Warfare (Bioterrorism)




Exam
ples of organisms: anthrax, smallpox, plague, botulism…





5


V.

Gene

therap
y:
Inserting DNA into cells to treat genetic disease, infectious diseases,
injury, and cancer
.






A. Procedure



Removal of blood cells



Culture white blood cells (T cells) in la
rge numbers



Insert the normal gene in the blood cells with a genetically engineered virus




Grow the genetically engineered white cells to increase their number (billions)



Inject billions of T cells back into the
same patient








B. Concerns/Probl
ems



1. Ideally, a virus will be found that….




-
Will infect the tissues that require the gene.



-
Will not cause the immune system to destroy the genetically

engineered cells.



-
Can be genetically manipulated to infect the cell and insert the

genes,
but will not cause harm to the host (allergic reactions,

toxicity).











6


2. Inserted genes incorporate into the chromosome randomly.



Therefore, it is possible for a
different

gene to be mutated and



incorrectly
expressed/not expressed.



http://news.bbc.co.uk/1/hi/health/2295707.stm

Gene therapy trials halted



Rhys Evans underwent gene therapy in
the UK in April

2000 for x
-
SCID.

Children with x
-
SCID or "bubble
boy"
disease are born

without a functioning

immune system.
They must live in
sterile conditions or risk picking up a
life
-
threatening infection.
This is caused
by a single mutated gene.
The x
-
SCID
gene therapy
trials involve
d

taking a sample of bone marrow cells and deliberate
ly
infecting them with a retrovirus modified to carry the corrective gene. The retrovirus
-

from the same virus family as HIV
-

inserts the therapeutic DNA randomly i
nto the cells'
chromosomes. It is

hoped that when the cells
are

returned to the patient, t
hey are able to
initiate the creation of a functioning immune system.

In 2000
, doctors at Great Ormond Street Hospital in London cured 18
-
month
-
old Rhys
Evans of the condition

by inserting the ‘good’ gene into his bone marrow cells using this
procedure.


However, two French boys were also treated in the same manner for the same disease. At
first, t
he treatment was considered to have worked well. However,
in 2002 it was
reported that
the newly incorporated DNA accidentally interrupted a gene responsible
for
controlling cell division
,

and these boys
started to produce too many white blood cells,
developing
leukemia.

According to
reports
, the boys responded

well to chemotherapy.
Twelve other boys that
received the gene therapy are doing well.

Trials using

this type of virus were halted in the U.S. and France.










7

3. Many genes require precise regulation (they are only expressed at certain


times in certain amounts). Inserted genes may not be regulated correctly



and damage the cell. Therefore, it
is best (at this time) to only insert genes


that are normally expressed at all times.




Structural gene:




Regulatory gene:






4. No one is sure of the long
-
term effects of inserting genes in germ cells.


Since all future generations would be affec
ted, this procedure is banned at



this time.




5. Clinic Trial Oversight


From:
http://bioethics.net/hsbioethics/coreGene/caseStudy.shtml

17
-
year
-
old Jesse Gelsinger suffered from a genetic disease called ornithine
transcarbamylase (OTC) deficiency. OTC deficiency is a genetic disease that prevents the
body from breaking down ammonia, which is a metabolic waste product
2
. In OTC
patients
, the excessive build
-
up of ammonia often causes death soon after birth,
unless the patient's diet is immediately adjusted and monitored throughout their
entire life. Jesse had lived on a strict diet and he controlled his OTC fairly well.
Jesse volunteered

for a gene therapy experiment designed to test possible
treatments for OTC

to help

newborns afflicted with OTC
. In this gene therapy
experiment, a virus
carrying a normal OTC gene was injected into his liver. The
virus

being used to deliver the OTC gene w
as
an

adenovirus
-

which is a
one

of
the virus
es

that causes cold
s
. For the most part, Jesse was informed subjects had
received adenovirus without serious complications. But for some reason Jesse
was different. After injection of the vector, a fatal reactio
n was triggered. On September
17, 2001, four days after the injection, Jesse Gelsinger died.






2

In
carnivores

protein is one of the largest components of the
d
iet
. The
metabolism

of proteins by the body
releases
ammonia
, an extremely toxic substance. It is then converted i
n the liver into
urea
, a much less toxic
chemical, which is
excreted

in
urine
.


Jesse Gel si n
ger


8





Problems:




Selection of Subjects
: He was relatively healthy and was in this trial to
help others, not himself




Informed Consent
: Parents were not given all o
f the facts concerning
possible harm




Conflict of Interests.
The guiding principle is clear: clinical investigators
must be able to design and carry out clinical research studies in an
objective and unbiased manner, free from conflicts caused by significan
t
financial involvement with the commercial sponsors of the study.
http://www.asgt.org/















6. Eugenics: process of deliberately manipulating the human genome to



produce a particular type of offspring, usu
ally to improve the quality of



the human race.









9

VI. Cloning



A. Much confusion happens when people see the word
"clone"

used. Depending

on the usage, the term cloning can mean several different things:




Reproductive (organism) cloning
: Produci
ng an
entire organism

that contains
the same DNA.





Therapeutic Cloning:
This procedure doesn’t produce an entire organism, but
instead produces
tissues or an organ
that are

g
enetically identical to an existing
person. These genetically identical tissue
s, or organs

are transplanted back into
the person who supplied the DNA.




Cell Cloning:
Genetically identical

cells

produced by cell division from an
original cell. This is where the cell creates a copy of all of the chromosomes and
splits into two daugh
ter cells. This is how cells are produced in the body when
children grow or are replaced when cells are damaged. Bacteria and other single
-
celled organisms exhibit asexual reproduction by producing genetically identical
daughter cells through DNA replicat
ion and cell division.




Molecular/DNA/ Gene Cloning:
Identical DNA

molecules

are produced using
molecular biology techniques. Copies of one gene or any sequence of DNA are
produced, usually by inserting the gene into an organism (for example, bacteria)
and

allowing that organism to replicate the DNA before it divides into daughter
cells. The copies of the DNA are in the living cells until needed. PCR also may
be considered a form of DNA cloning.


10


B.
(Somatic Cell) Nuclear Transfer:

Often referred to as

Reproductive Cloning
. This technique produces a duplicate of an
existing

animal.

It

has been used to clone sheep and other mammals.

Genetically identical organisms are produced by f
irst removing or destroying the DNA
from an egg (oocyte). The egg’s DNA

is replaced by
inserting the nucleus from another
existing animal’s
somatic

cell into the enucleated egg. Somatic cells have the full
complement of DNA, so the egg is ‘tricked’ into believing it has been fertilized.

Then, the zygote divides and is then i
mplanted in a uterus and allowed to develop into a
new animal.


1. Remove the nucleus or destroy the DNA of the egg.






2. Incorporate the DNA from a somatic cell of a different animal.










3. The above cell is essential a zygote.







4. Allow th
e zygote to divide and then implant.









C. Human Cloning
????????