Transcript Leq: what is cloning and how is it done?

LEQ: WHAT IS
CLONING AND
HOW IS IT DONE?
11.10 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 1st 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?)