February 19, 2014 – Section IV: Human Cloning
How to study for this unit:
1. Understand what’s in the book
2. Pay attention to the words in bold and italics.
3. Use the slides to help you understand the book. (Not in place of the book)
4. DO THE PRACTICE PROBLEMS! (ESPECIALLYTHE ONES THAT INVOLVE
INTERPRETING THE GRAPHS)
• Brief history of human cloning
o 1962: First successful animal cloning (of frogs)
o 1997: First successful full-term cloning of a mammal (sheep)
Many agricultural animal cloning successes have followed.
o 1998: Claim of four-cell cloned human embryo (Two cell divisions – this
experiment was not reproduced, however.)
o 2002: Clonaid claims to clone twelve humans – not true, never substantiated
o 2004: South Korean group published in Science creating of several human
blastocysts by cloning – this claim turned out to be based upon fabricated date and
was retracted in 2006.
o 2007: First primate blastocysts by cloning (Oregon Primate Res. Control)
o 2013: First human blastocysts by cloning (Oregon Primate Res. Control)
• Genomic equivalence – the idea that all cells in the body have the same DNAdespite
wide variation in appearance and function. THIS IS TRUE. Cells all have the same
o Demonstration of genomic equivalence opens up new horizons.
Regenerative medicine – the ability to regenerate damaged or diseased
tissue using cells from more easily derived tissues (skin, blood) as a
source of material.
Cloning – also means that cloning is possible.
• Nobel Prize in medicine for demonstrating the concept of genomic equivalence
o John B. Gurdon in 1962
Circa 1962 – the nucleus from an intestinal cell can replace the pronucleus
of an egg and develop into an entire animal. o Shinya Yamanaka in 2006
• Since 1997 with the cloning of Dolly the sheep, many different farm and laboratory
animals have been cloned.
• Cloning involves the replacement of an egg’s genetic material (its pronucleus) with that
of another cell.
• SCNT is the procedure of injecting the nucleus from the differentiated cell into the
enucleated egg (commonly called somatic cell nuclear transfer).
o After SCNT, you must trick the egg into thinking it has been fertilized by sperm.
This usually just involves some kind of shock.
o Optional – transfer to the uterus of the surrogate mother – this can only now occur
• Two types of cloning – reproductive is what most people think of, but there is also
• Safety issues with reproductive cloning are prohibitive.
o Dolly – 434 embryos, 29 blastocysts, many deformed births
o Only 1 out of 150 mouse attempts produces an animal.
o 1 out of 600 for pigs
o Are these individuals “normal”?
o No known legitimate cases for humans.
• Why clone human beings?
o Reproductive Cloning – implanting the cloned blastocysts into the uterus of a