Ch.10-4 Cell Differentiation CELL DIVISION

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

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

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

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

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

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)

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

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

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

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)

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)

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

Homework Read pages 292-297 Assess page 297 #1-3 Workbook pages 114-116 Ch. Rev. Pg 300: #3-4, 6-16, 19-22, 24-31 Pg 303: #1-7