Transcript Slide 1
REPRODUCTIVE CLONING Definition = making an exact genetic copy of an organism. Occurs naturally with identical twins Lab methods - artificial twinning - Somatic Cell Nuclear Transfer Artificial Twinning • Similar to how identical twins form • Early stage embryo (blastocyst) is pulled apart artificial twinning process Somatic Cell Nuclear Transfer • Somatic cell = any body cell (not sex cells) • Oocyte = egg • Enucleated = nucleus is removed; click link and select “Enucleation Video” on right-hand side Somatic Cell Nuclear Transfer cont. • In SCNT, any somatic cell is fused with an enucleated donor oocyte. • “Fertilized egg” is given a shock and transferred into a surrogate female. • Result is genetically identical to the somatic cell donor. (Animation) Why Clone? • Preserving endangered or recreating extinct animals. • Restoring the life of a lost pet. Why Clone? • Making exact copies of livestock or crops that have prized traits. What animals have been cloned? ANIMALS THAT HAVE CLONED BY SCNT • Tadpole • Carp • Sheep • Pig (xenotransplantation = using animal organs in humans) • Gaur • Cattle • Cat • Mule • Deer • Horse (Champion the Wonder Clone) • Rat • Fruit Flies • Dog ANIMALS THAT HAVE BEEN CLONED BY ARTIFICIAL TWINNING • Rhesus Monkey What animals have been cloned? ANIMALS THAT HAVE BEEN CLONED BY ARTIFICIAL TWINNING • Rhesus Monkey Any Problems With Cloning? • Video 1. High Failure Rate - Success rate ranges from 0.1 – 3% - Dolly was result of 277 attempts! Any Problems With Cloning? 2. Large Organ Syndrome • Kidney, brain, immune system malformation Any Problems With Cloning? 3. Abnormal gene expression • Same genes, but body isn’t using them the same as the original. Any Problems With Cloning? 4. Telomere is too short • Shorten as we age • Dolly started with shorter than normal telomeres • Developed arthritis at an early age Cloning Misconceptions • Myth #1 – Instant Clone Cloning Misconceptions • Myth #2 – Carbon Copies • Nature vs Nurture • In females, X-inactivation - each cell can’t have multiple copies of the X chromosome - each cell randomly chooses which X chromosome to inactivate - female clones are not phenotypic clones Should we clone humans?