Rim Ali, Noor H, Fankah M, Shaima M Group 3B The Cell Cycle Rim Ali, Noor H, Fankah M, Shaima M Group 3B

Cell Differentiation Cellular Differentiation is the process where one cell type changes from one cell to another. Cells come from preexisting cells by the development of mitosis and cytokinesis (pg.68). Stem cells specialize and take specific functions like mature tissues like skin, muscle, blood, bone, bone, liver, nerves, all have different types of cells. A progenitor cell is a biological cell that, like a stem cell, has a tendency to differentiate into a specific type of cell. The most important difference between stem cells and progenitor cells is that stem cells can replicate endlessly, whereas progenitor cells can divide only a limited number of times.

Stem Cells Stem cells can gradually develop into many different cell types in the body during growth. They can serve as an internal growth repair system in the body. When a stem cell divides each new cell can either become a new type of cell or remain a stem cell. Stem cells can divide in order to repair or replace damaged tissues.[1]

Figure 3.23 A cell lineage is the developmental history of a differentiated cell as traced back to the cell from which it arises. Cell lineages can trace the paths of differentiation as well. (pg. 71) Stem cells may have been placed in organs and set to the side in embryos or fetuses for mending. In this figure it how every cell in the body originated from a stem cell through cell division and differentiation.

Cell Death A cell that that does not divide or specialize has a prerogative of dying. Apoptosis is the death of cells that occurs as a normal and controlled part of an organism's growth or development (pg 72). Apoptosis shapes organs for naturally occurring overgrown tissues.

Major Steps of Apoptosis Cell shrinks Cell fragments Cytoskeleton collapses Nuclear envelope disassembles Cells release apoptotic bodies[3]

Basically, what Apoptosis is when a cell commits suicide Basically, what Apoptosis is when a cell commits suicide. It has an impact in biological processes including embryogenesis, ageing, and many diseases. Studies undoubtedly show that apoptosis is genetically regulated.[3]

Relationship Between Diseases and Apoptosis Decreased or inhibited Apoptosis is a feature of many immune disorders and some viral infections. The role of Apoptosis in cancer has received the most amount of research efforts. Apoptosis kill cancerous cells and tumors in the immune system it is known in tumors as “tumor counterattacks”

Fetuses Apoptosis carves away webbing between fingers and toes resulting in the removal of brain cells and protects immune system cells that recognize the body’s cell surfaces. [3]

Question Time! Define Differentiation. Why must cells divide and specialize? What are the steps of Apoptosis? What is the difference between a stem cell and a progenitor cell?

Sources "Save Time and Improve Your Marks with CiteThisForMe, The No. 1 Citation Tool." Cite This For Me. N.p., n.d. Web. 28 Sept. 2016. Shier, David, Jackie Butler, and Ricki Lewis. Hole's Essentials of Human Anatomy & Physiology. Boston: McGraw-Hill Higher Education, 2009. Print. "Cell Biology 11: Apoptosis & Necrosis." Cell Biology 11: Apoptosis & Necrosis. N.p., n.d. Web. 28 Sept. 2016.