3 Types Of Cloning by oprahfan143

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									BIO108: Human Biology                                                                        UNC-Asheville, s2008

                                                    Making a copy of a gene or an entire organism using DNA
                                                                  from an existing individual.

                           Cloning                                                 CLONE
                                                    Any copy having the same genetic makeup as the original
                                                                        biological entity

                           Ashley Donald
                             BIO 108


                                                 3 types of cloning:
                   Types of Cloning
                                                  1. Gene (DNA) cloning
 • Gene Cloning – produces copies of genes        (recombinant DNA)
   or segments of DNA                              transfer of a DNA fragment of
                                                   interest from one organism to a
 • Reproductive Cloning – produces copies          self-replicating genetic element
                                                   such as a bacterial plasmid
   of whole animals
 • Therapeutic Cloning - produces a cloned         The DNA is then propagated in
                                                   the foreign host cell.
   embryo to create embryonic stem cells for
   understanding and developing treatments

                                                 3 types of cloning:
 Some uses of this technology
 1. Isolation of a particular gene, part of a
 gene or region of a genome                      2. Reproductive Cloning
 2. Production of a desired RNA or protein       make new, genetically-identical copies
 molecule in large quantities                    of an organism, by using its own DNA
 3. Increased production efficiency for          create “identical” twin, born years later
 commercially made enzymes and drugs
 4. Modification of existing organisms so that
 they express a trait not previously encoded
 in the genome (transformation)

BIO108: Human Biology                                                                                                              UNC-Asheville, s2008

                   Reproductive Cloning Process
                                                                                                         Reproductive Cloning
                                                                                                 • Ex. Dolly the Sheep (1996)
                                                                                                 • DNA originally from a mature somatic cell is
                                                                                                   added into an empty oocyte (egg)
                                                                                                 • Once the egg has developed into an early-stage
                                                                                                   embryo inside a test-tube, it is implanted into the
                                                                                                   womb of an adult female animal.
                                                                                                 • Cloned animal does not always look identical to
                                                                                                   the original animal.


                                                                                                 What Animals Have Been Cloned?
                                                                                                 •   Mice                                  •Mule
                                                                                                 •   Cows                                  •Ox
                                                                                                 •   Sheep
                                                                                                 •   Chickens                              •Pig
                                                                                                 •   Cat                                   •Rabbit
                                                                                                 •   Deer
                                                                                                 •   Dog
                                                                                                 • Horse

                Potential Applications of                                                                 Potential Drawbacks of
                 Reproductive Cloning                                                                      Reproductive Cloning
 • Medicine                                                                                      • At least 95% of cloned animals are too
      – Drug and Treatment Testing                                                                 unhealthy to properly develop.
 • Agriculture                                                                                          Increased birth size, defects of vital organs,
      – Genetic Modification of cloned livestock for                                                    premature aging, immune system function, shorter
        nutrient benefits                                                                               life span

 • Population Building of Endangered and                                                         • If development occurs, cloned animals risk
   Extinct Species                                                                                 early death.
      – Resulting species could lack genetic

BIO108: Human Biology                                                                                                  UNC-Asheville, s2008

           Cloning of Humans                                                Cloning of Humans
 • Claims:                                               • Difficulties:
    – South Korea (1998)                                     – Spindle proteins (essential in cell division) are
    – Clonaid (2002) – claimed 13 human clones                 located too close to the chromosomes. Thus,
    – Woo-Suk Hwang of Seoul National University               removal of the nucleus likely results in
      in South Korea (2004)                                    removal of the spindle proteins as well.
                                                             – Dyes and UV light used to remove a nucleus
                                                               can damage primate cells.

                                                        3 types of cloning:
           Cloning of Humans
                                                        3. Therapeutic Cloning1
 • Ethical Issues:                                      make new identical copies of an
    – Could allow for “manufactured” children with      organism’s cells, using its own DNA
      desired traits and characteristics                make an early “embryo” (cell mass) from
                                                        patient’s cells and use it as a source of
    – Unrealistic expectations of the clone’s           stem cells
      similarity to the cloned individual               these cells can potentially be used to
                                                        replace diseased organs, cancerous
    – Could allow for the cloning of a deceased         tissues, etc.
                                                        1sometimes   called somatic cell nuclear transfer

                                                             Therapeutic Cloning Process
           Therapeutic Cloning

 • Performed by removing healthy adult cells from
   a patient, reprogramming the cell’s nuclei,
   collecting and growing embryonic stem cell
   clones from the resulting blastocyst, and then
   inducing these to differentiate into the stem cell
   or mature cell types required for transplantation


BIO108: Human Biology                                                                                                      UNC-Asheville, s2008

                 Therapeutic Cloning                                        STEM CELLS
                                                                            •     Unspecialized cells
 •    Potential Application                                                 •     Renew themselves by division (mitosis) for long periods
             -- To replace diseased or injured tissues
             -- To learn more about the causes of disease
                                                                            •     Under certain conditions, can be induced to become cells
                                                                                  with specific functions (heart muscle cell, lymphocyte)
 •    Potential Drawbacks
                                                                            •     Embryonic stem cells and adult stem cells
        -- Some studies show that after 60 cycles of cell division, stem
           cells can mutate and lead to cancer                              •     Stem cells can be clones of adult cells (transfer of nucleus)
 •    Ethical Issues                                                              or more commonly, produced by in-vitro fertilization
            -- Potential of creating a cloned human
             -- May violate values of individual freedom, identity, and
             -- Could help sterile couples have children
             -- Requires destruction of human embryos in a test tube.

Embryonic Stem Cells
Undifferentiated cells that can potentially develop into any kind of cell
Not harvested from mother or embryo, but created in vitro (laboratory)      Embryonic Stem Cells
“cell culture”                                                              • not implanted into the uterus
Cells used are at blastocyst stage                                          • used to study development
(~30 cells; no parts, tissues or organs)
                                                                            • may be mixed with chemicals to
Similar process to in-vitro fertilization                                   help the cells take on different
(“test-tube baby”), except embryonic                                        properties
stems cells are not implanted into                                          • ultimately may be able to
mother                                                                      introduce these cells into an adult
                                                                            (therapeutic cloning)

“Adult” Stem Cells
Somewhat differentiated cells that can develop only into specific tissues
(eg. Lymphocyte stem cells)                                                     “Adult” Stem Cells
                                                                                • Somewhat differentiated cells
                                                                                • Can develop into certain tissues, but not necessarily all
                                                                                tissues in the body
                                                                                   Blood stem cells can develop into RBCs, WBCs, but not muscle cells
                                                                                • Can be extracted from adults, ex. from bone marrow sample
                                                                                (don’t require creation of embryo)

    BIO108: Human Biology                                                                                                          UNC-Asheville, s2008

                               Why Stem Cells?

        Potential benefits of stem cell research:
            • understand how development works
            • understand how evolution works
            • diagnose and remedy birth defects
            • replace damaged/diseased organs and tissues
            (grow your own tissues)
            • help to cure cancers & other diseases (replace
            diseased or malfunctioning cells with healthy cells)
            • substitute case for testing new drugs

                         Ethical Issues to Consider
     • What is a human? Does a cell or group of cells, which are grown in the
     lab and never implanted into a mother, deserve the rights of a human?
                                                                                   This isn’t science fiction –
     • Is this technology too powerful? Are we trying to tamper with human
     biology too much? [unpredictable consequences]                                These are real technologies, and remarkable opportunities and advances
                                                                                   in biotechnology will become available within your lifetime.
     • Will we be able to engineer children to have specific traits? (ex. to get
     rid of genetic disease? Tendency towards obesity? Blue eyes?)                 The ethical issues involved deserve your serious thought, and it is worth
                                                                                   understanding basics behind the technology to help make your decisions.
     • Although there may be no limits on what we can modify, are there limits
                                                                                   Many (most?) of our political leaders have less understanding of scientific
     on what we should modify?
                                                                                   basis behind these issues than you now do.
     • Who will have access to this technology? Who will pay for it?

                               Sources Cited

•   Cloning. The National Human Genome Research Institute.
•   Gene Cloning. University of Nebraska –Lincoln.
•   Reproductive Cloning. Center for Genetics and Society.
•   Therapeutic Use of Cell Nuclear Replacement: Therapeutic Cloning.
    Medical Research Council.

                          For Further Information:

•   Cloning in Focus. Genetic Science Learning Center at the University of
    Utah. http://learn.genetics.utah.edu/units/cloning/
•   AAAS Policy Brief: Human Cloning. AAAS Center for Science, Technology
    and Congress. http://www.aaas.org/spp/cstc/briefs/cloning/index.shtml


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