1. Ch.10-4 Cell Differentiation
CELL DIVISION

2. POINT > Define cell differentiation
POINT > Describe cell fate in simple organisms
POINT > Describe cell fate in complex organisms
POINT > Identify types of stem cells
POINT > Consider ethics of stem cell therapies

3. POINT > Define cell differentiation
Differentiation is the process by which cells become specialized to perform specific functions (muscle, skin, nervous, etc)

4. POINT > Describe cell fate in simple organisms
Scientists can map the identity and development of cells
C. elegans –
The cell fate of all 959 cells of the organism is known and does not change
Removing a particular cell results in the worm missing those structures
Nervous
5th Division
Pharynx
9th Division
Cuticle
8th Division

5. POINT > Describe cell fate in complex organisms
Scientists can map the identity and development of cells
Mammals are more complex and flexible. Cell fate is determined by many interacting factors
Removing a cell
signals neighboring cells
to divide and differentiate
to replace those missing

6. Which statement is false?
WB CHECK:
Which statement is false?
a) Cell differentiation in mammals is flexible and influenced by many factors
b) Cell differentiation in C. elegans is rigid: cell fates are pre-determined
c) Cell differentiation in mammals is rigid: cell fates are pre-determined
d) Cell differentiation produces specialized cells

7. POINT > Identify types of stem cells
Stem cells are the unspecialized cells from which differentiated cells develop
Some stem cells are totipotent: able to develop into any type of cell
(only a fertilized egg & cells of the first few cell divisions are totipotent)

8. POINT > Identify types of stem cells
Blastocyst
Pluripotent cells: Can develop into most, but not all, types of cells Embryonic stem cells are pluripotent

9. POINT > Identify types of stem cells
Multipotent cells: can develop into many types of differentiated cells, but only similar to the organ/tissue they are from
Multipotent cells are already partially differentiated, so they have less potential
“Adult” stem cells are multipotent

10. Which statement is false?
WB CHECK:
Which statement is false?
a) Adult stem cells are multipotent
b) A fertilized egg is totipotent
c) Embryonic stem cells are pluripotent
d) Adult stem cells have more potential outcomes than embryonic stem cells
e) Adult stem cells have fewer potential outcomes than embryonic stem cells

11. POINT > Consider ethics of stem cell therapies
Stem cells have potential to repair or replace damaged cells & tissues (due to heart attack, stroke, disease, injury, etc)

12. POINT > Consider ethics of stem cell therapies
Adult stem cells:
Embryonic stem cells:
Differing perspectives on their use:
Protection of embryo (it could become a human) VS
Research can save human lives and suffering, it’s unethical not to do it
No ethical concerns; from a willing donor
Harvested from very early embryos
(leads to destruction of that embryo)

13. The “Golden Ticket”?
Current research is working with adult stem cells to switch “on” genes allowing these cells to function as pluripotent embryonic stem cells
Some success, but other cell cycle issues have typically arisen after many cell divisions

14. Homework Read pages 292-297 Assess page 297 #1-3
Workbook pages
Ch. Rev. Pg 300: #3-4, 6-16, 19-22, 24-31
Pg 303: #1-7