1 Review What happens during differentiation2 Review What are stem cells Compare and Contrast How are embryonic stem

cells and adult stem cells alike and how are they different

3 Form an Opinion How might technological advances help address the ethical concerns surrounding stem cell research

CH 10 CELL GROWTH AND DIVISION 10.4 Cell Differentiation

All organisms start life as just one cell Embryo

Early stage of development most multicellular organisms pass through

Cells become more differentiated and specialized.

Differentiation

Process of cells becoming specialized.

Cell’s role can be determined at a specific point in development.

Differentiation in Mammals

Controlled by a number of interacting factors in the embryo Chemical signals Regulatory factors Interaction between cells

Adult cells generally can no longer differentiate.

Stem Cells

Unspecialized cells from which differentiated cells develop

Totipotent Can form all the tissues of the body Only the fertilized egg and first few divisions

Embryonic Stem Cells

Pluripotent Capable of developing into many, but not all, cell

types Located in inner mass of cells of blastocyst

Blastocyst Early embryo stage with a hollow ball of cells with a

cluster of cells inside

Adult Stem Cells

Multipotent Can produce many types of differentiated cells Typically produce only the types of cells that are

unique to that tissue where they are located.

Potential Benefits

Research may lead to new ways to repair the cellular damage that results from heart attack, stroke, and spinal cord injuries.

Ethical Issues

Most techniques for harvesting, or gathering, embryonic stem cells cause destruction of the embryo

Government funding vs. private funding.

Cellular Differentiation of C. elangans

The adult microscopic worm C. elangans contains 959 cells. Copy the data table and then answer the following questions.

1. Calculate Calculate the percentage of the total cell number reprented by each tissue or organ listed including ‘other’.

2. Infer Why does C. elanans make an ideal model for studying cellular differentiation

3. Infer Why would it be more difficult to map the differentiation patterns in a different organisms like a mammal