cloning 101. cloning is the creation of an organism that is the exact genetic copy of another...

CLONING 101

• cloning is the creation of an organism that is the EXACT genetic copy of another

– Identical twins are natural clones

• Cloning can be done artificially in a laboratory by one of two ways:

– Artificial embryo twinning– Somatic cell nuclear transfer (SCNT)

1. Artificial Embryo Twinning

• done in a Petri dish– Occurs just after fertilization

• Sperm fertilizes egg, forms the one-cell zygote• When zygote goes to divide into two cells, the cells

split from one another • Each cell divides and matures on its own,

becoming individual twin embryos

– The embryos are genetically identical

• Done after IVF (in vitro fertilization):– the egg is fertilized by the sperm directly in

the Petri dish– the cells of a very early embryo are split from

one another manually, so they can continue to divide and mature on their own

– the embryos are then placed in a surrogate mother.

2. Somatic Cell Nuclear Transfer (SCNT)

• (AKA How Dolly Was Created)

• There are two types of cells in the body– somatic (46 chromosomes, all except gametes)– germ cells (23 chromosomes, egg and sperm)

• http://learn.genetics.utah.edu/content/tech/cloning/clickandclone/

STEPS

a) isolate somatic cell

b) remove its nucleus (genetic info)

c) transfer nucleus to an egg that has had its own nucleus removed.

d) implant in surrogate mother

e) resulting organism is an exact clone of that which donated the somatic cell nucleus.

Why clone?• animal models of (human) disease

• stem cells for research

• “pharming”: large populations of genetically engineered animals to produce drugs

• revive endangered/extinct species

• reproduce deceased pets – yup, you can bring Fluffy back

• any reason to clone humans?– help infertile couples have children?– “replace” a diseased child?– make a perfect donor?

Risks of Cloning:

• high failure rate– success rate 0.1-3%

• problems later in development– blood flow and breathing problems– telomeric differences (chromosome ends

shorten as we age) leading to premature aging

• abnormal gene expression

• clones will not necessarily look alike, nor will they act alike!!!

• http://www.youtube.com/watch?v=dzJx2dl8MA8

Two Types of Cloning:1. Reproductive Cloning

• creates an organism with the same genetic material (DNA) as the original organism – an EXACT COPY of the donor

• NOT LEGAL (for humans!!!!)

2. Therapeutic cloning

• used to produce tissue that is identical to the donor, to prevent rejection

ISSUES

• So...– ethical: moral outcomes?– legal: how should this be regulated?– social: how will this affect society?

• Questions to ask yourself:– what are the risks/benefits?– whom will this hurt/help?– what does this mean for me and my family? others?

Do the benefits of cloning outweigh the costs in regards to the uniqueness of human beings?