cells  tissue  organs  organ systems  organism

Is asexual reproduction good? How fast do you need to reproduce? How many offspring do you want to have? Is there a partner to reproduce with? Do you have what is needed to attract a mate? Is the environment changing around you? Is this environment suited for mating? Do you need genetic variation to survive?

Stem Cells Stem cells are unique body cells. Stem cells have the ability to divide and renew themselves remain undifferentiated in form develop into a variety of specialized cell types

Types of Stem Cells Cells from early (1-3 days) embryos Some cells of blastocyst (5 to 14 days) ??? Umbilical cord stem cells

How using ESCs works: Q: Where do they come from??? A: Leftover in vitro fertilization elements

Stem Cells combined with Cloning http://whyfiles.org/148clone_clash/images/clone_big_chart.gif

Adult Stem Cell Possibilities http://www.xcell-center.com/media/7679/stem_cell_specialisation.jpg

Many Possibilities: Replaceable tissues/organs Repair of defective cell types Delivery of genetic therapies Testing of new drugs

Challenges It is uncertain that human embryonic stem cells in vitro can give rise to all the different cell types of the adult body. It is unknown if stem cells cultured in vitro (apart from the embryo) will function as the cells do when they are part of the developing embryo Stem cells need to be differentiated to the appropriate cell type(s) before they can be used clinically. Embryonic stem cells (ESC) stored over time have been shown to create the type of chromosomal anomalies that create cancer cells.

Challenges (cont.) Stem cell development must be controlled once placed into patients. Possibility of rejection of ECS transplants as foreign tissues is very high. Contamination by viruses, bacteria, and fungi possible. The use of mouse “feeder” cells to grow ESC could result in problems of transplantation (many animals have tissue which ages faster than humans).

“Personality” definition problems What defines a “life” or “person”? What traits define personhood? Who makes the definition? Does a human non-person exist? Society has excluded certain humans from personhood before (e.g., African slaves, Chinese, etc.) Should we make a new list of human non-persons?

Other ethical questions… Is there a difference between humans and other “animals”? Is there such thing as greater good- who gets to decide what this is? How should cloned animals/humans be treated as individuals?