LEQ: WHAT IS CLONING AND HOW IS IT DONE? to 11.12

CLONING  Cloning is the creation of a genetic copy of a sequence of DNA or of the entire genome of an organism  There are three basic types of cloning 1. Recombinant DNA technology – the transfer and copying a segment of DNA from one organism to another 2. Reproductive cloning – generating an entire organism that is genetically identical to an existing organism 3. Therapeutic cloning- the production of human embryos for the purpose of harvesting stem cells for research purposes

Dolly The 1 st successful mammal clone created from a specialized body cell. Created at the Roslin Institute of Edinburgh University under the direction of Ian Wilmut There was concern that she would be born “old” because her DNA was from an adult sheep. Her telomeres were shorter than other sheep of her age but not as short as an “old” sheep. This could have played a role in her short life span (6 years – normal 11 to 14 years) Before she died of cancer she was able to give birth to 6 lambs, the first of which was named Bonny

Reproductive Cloning Egg cell nucleus (haploid) is removed and replaced with a somatic cell nucleus (diploid) The egg cell is stimulated to induce cell division; Once the dividing egg cell reaches the embryo stage it is implanted into a surrogate mother The embryo develops into a living organism

Benefits and Problems with Reproductive Cloning Benefits: Genetic Research Restock populations of endangered animals Insure that “good” genes are passed to the next generation Problems: Costly and inefficient (90% of the time it doesn’t work) Short lifespan Susceptible to disease and illness results in early death

Ethical Issues with Reproductive Cloning Technical and medical safety Undermining the concept of reproduction and family Ambiguous relations of a cloned child with the progenitor Confusing personal identity and harming the psychological development of a clone Concerns about eugenics Contrary to Human Dignity Promoting trends towards designer babies and human enhancement

Therapeutic Cloning Follow similar steps to reproductive cloning placing a somatic cell nucleus into an empty egg cell and stimulating cell division Big Difference – the embryo is never implanted into a surrogate Instead, once the dividing egg reaches the blastocyst stage in development stem cells are harvested Embryonic stem cell lines are then established for research purposes

Benefits and Problems with Therapeutic Cloning Benefits: The stem cells harvested can develop into any type of cell; Can be used to develop treatments to diseases and possibly be used to create tissues/organs for transplant purposes without worrying about rejection by the immune system Problems: Costly and inefficient; requires that the embryo be destroyed so that stem cells can be harvested (is a blastocyst a living being?)