Differentiation and Stem Cells Notes #21 I can: Explain that all cells come from stem cells and then get differentiated

Nerve cell

Smooth muscle

Skeletal muscle

Adipose tissue cells

Skin cells

Bone cell (osteoblast)

Cheek cell

Blood cells

However, every cell in an organism contains the same DNA. There are around 200 specialized cell types in the human body, each type with a specific function. How is this possible? However, every cell in an organism contains the same DNA.

Not all genes are turned on at one time. Gene Expression Not all genes are turned on at one time. Different cell types have different parts of their DNA expressed, or turned on. Nerve cells only have the “nerve genes” expressed at any time. The “nerve genes” are transcribed into mRNA, and translated into “nerve proteins.” Muscle cells only have the “muscle genes” expressed at any time. The “muscle genes” are transcribed into mRNA, and translated into “muscle proteins.”

Because different genes are expressed in different cell types, different proteins are made and cells become specialized. The process of cells specializing is called differentiation.

Each of the specialized cell types found in our bodies developed from the same fertilized egg. How is this possible?

Stem cells are cells that have not yet differentiated. By expressing different genes, stem cells can become many other types of cells. Two types: embryonic stem cells; hematopoietic (adult) stem cells

Embryonic stem cells come from fertilized eggs that have developed for ~5 days. can turn into ANY type of cell. Adult (hematopoietic) stem cells are found in your bone marrow. constantly renew your blood cells.

Scientists have learned how to direct adult stem cells to turn into any cell type. Possible applications: growing organs in the laboratory to replace damaged ones growing new skin for a burn victim replacing defective insulin-producing cells in patients with diabetes

To Do: Read articles (DO NOT WRITE ON) Answer questions #1-5 with partner Each answer on individual papers & turn in Return article back to side table!!!! IP: Differentiation (in packet) Exit Ticket