Steps in cloning via nuclear transfer. A &B) Nucleus
is sucked out of egg cell, C) pipette picks up nucleus, D) Pipette has
squirted nucleus (faint dark spot) into egg, transfer is complete.
Courtesy Roslin
Institute.
Nuclear transfer cell about to be activated by
an electric jolt between the two black electrodes. After activation, the
embryo starts dividing normally.
Courtesy Roslin
Institute.
To understand the cloning debate (and to distinguish cloning from genetic engineering, which many opponents fail to do) we need to dig some crazy lingo:
Reproductive cloning:creating a new organism from a single cell of an adult. The genes (but not the far less-important mitochondrial DNA) of the offspring are identical to the parent.
Therapeutic cloning: creating embryos to supply embryonic stem cells as a source of spare parts to treat disease.
Genetic engineering: changing genes in cells that will be transmitted to all offspring, was recently used to make pigs that may supply compatible transplant organs for people.
Genetic
engineering might help in therapeutic cloning -- since the patient's cells
would carry any genetic defect that caused the disease in the first place.
However, manipulation of cells involved in human reproduction is risky
and controversial, since it would bequeath today's mistakes on tomorrow's
generations. The Why Files knows of no serious proposals to genetically
engineer human embryos.
Shall we clone?
Similarly, it's hard to find a responsible ethicist
or scientist who makes a strong argument for reproductive cloning, certainly
at this stage of scientific development. But it's easy to find patient
advocates and medical researchers who want to use therapeutic cloning
to develop revolutionary treatments for deadly diseases.
Therapeutic cloning might, after all supply islet cells to treat diabetes or dopamine-producing cells to treat Parkinson's disease.
Embryonic stem cells are now derived from surplus in vitro fertilization (IVF) embryos, but to eliminate rejection, it may be better to get them from human embryos made in the laboratory.
But therapeutic cloning appalls those who believe life begins at conception, and who want to ban all cloning under pending state and federal bills.
Not
birds. Definitely not bees
Cloning flouts nature's tried-and-true "birds 'n bees" techniques of reproduction.
To make embryos or cells that are genetically identical to the "parent"
organism, scientists use a technique called nuclear transfer -- the same
method that produced Dolly the sheep.
Nuclear transfer uses eggs, but it skips the sex and the sperm.
Odd.
Get me the repro man! What is reproductive cloning and why does everybody despise it?
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