Cloning+plants+and+animals

//by Shally and Kellie//
__**//Plants//**__ Organism Cells have genomic equivalence, or the idea that all have similar genes. Attempts to generate a whole organism from differentiated cells of same type. In plants, new organisms can develop from differentiated somatic cells -Somatic cells (nonreproductive cells) Differentiated Cells removed from roots of a plant and placed in culture medium could grow into normal plant adult plants. Similar and identical to parent plant. Cornell university, carrot plant experiment: Took carrot root fragments and placed into culture medium and allowed the fragments to culture in nutrients, the embryoid develops from cultured fragments and transferred to soil where new adult plant grows.
 * Cloning** is the process of taking a single somatic cell from a multicellular organism to create a new identical organism.
 * Totipotent** is the idea that plants can retain the zygotes potential to form all parts of the mature organism.
 * EXPERIMENT**:

Signifigance: Used widely in agriculture Show that differentiation does not involve irreversible changes in DNA

__**//Animals//**__
 * Differentiated cells from animals often fail to divide in culture, not developing into a new organism
 * Researchers study genomic equivalence in animals by replacing the nucleus of an unfertilized egg cell or zygote with the nucleus of a differentiated cell. This is known as **nuclear transplantation**.

1950s Briggs, King, and Gurdon experiments:
 * Removed nucleus from a frog cell egg and transplanted a nucleus from an embryonic or tadpole cell
 * Found that the age of the donor was inversely proportional to the ability to support normal development; most of the cells that received nuclei from embryo (relatively undifferentiated) developed into tadpoles, while the ones that received nuclei from tadpoles ( differentiated intestinal cells) did not.
 * Concluded that nuclei change as cells differentiate because of chromatin structure; cells all have the same genes but express different portions

1997 Wilmut experiment Issues
 * Cloned an adult sheep by transplanting the nucleus from a mammary cell into an unfertilized egg from a different sheep and implanting resulting embryos in a surrogate mother
 * Achieved dedifferentiation of the nucleus by culturing the mammary cells in a nutrient-poor medium, leading to arrest of the cell cycle
 * One of several hundred of the embryos completed normal development- Dolly
 * Since then cloning has been demonstrated in many mammals important to agriculture
 * Farm animal cloning raises safety issues
 * Possibility of human cloning raises ethical issues
 * Only a tiny percentage of cloned embryos develop normally because their DNA is improperly methylated