1. Cell Differentiation (10.4)

2. The Process of Cell Differentiation
Embryo: the process that eventually forms an adult organism through the process of cells differentiating, or specializing, into more specific cells
Differentiation: the process by which cells become more specialized
cells differentiate into many different types of cells to perform specific functions we need to maintain homeostasis and stay alive
the process of differentiation determines a cell’s ultimate identity -- nerve cell, muscle cell, etc.

3. Stem Cells and Development
Cell Development
zygotes, or fertilized eggs, are totipotent, or able to do anything to develop into any type of cell in the body
blastocyst: a hollow ball of cells with a cluster of cells inside known as an inner cell mass
It takes four days for a blastocyst to form
Cells begin to specialize into tissues
the inner mass of cells are pluripotent, or able to form any kind of cell except tissue surrounding the embryo

4. Stem Cells
Stem cells: the unspecialized cells from which differentiated cells develop
they are at the “stem” of development from which each cell develops
stem cells are found in early embryos but they are also found in adults as well
Adult Stem Cells
multipotent: the types of differentiated cells they can form are limited to replacing cells in the tissues where they are found
Ex: blood cells, skin cells, brain cells, heart cells
Embryonic Stem Cells
they are pluripotent cells that can differentiate into any type of cell

5. Potential Benefits Ethical Issues
damage caused by severe heart attacks can be reversed by stem cells → stem cells can also treat brain damage, regenerate nerves, or repair organs
undifferentiated cells are used to repair or replace damaged cells and tissue
adult stem cells can be harvested from a consenting adult; however, stem cells are obtained from the destruction of an embryo
Groups argue against stem cell research because it is unethical to harm an embryo

6. Induced Pluripotent Stem Cells
an alternative to stem cells research where embryos are needed to repair damaged cells and tissues
fibroblast cells were turned into cells that closely resembled embryonic stem cells (researcher: Shinya Yamanaka)
iPS cells make it possible to tailor specific therapies to the needs of each individual by using their own cells → this process eliminated the need of stem cells from embryos → no ethical issues involved