The Cell Cycle Ch. 10

Cell Cycle Regulation Cell growth and division are carefully controlled. Not all cells will go through the cell cycle at the same rate. Examples of cells rapidly dividing: Examples of cells NOT dividing often: Skin cells RBC Muscle cells Nerve cells Bone marrow /2009/05/red-blood-cells.bmp http://stearn.ca/blog/wp-content/uploads _Cancer_(Non-Meloma)/The_Basics/Epidermis-dermis.jpg http://www.caring4cancer.com/uploadedImages/Website-C4C-20/Skin Digestive tract cells http://apps.uwhealth.org/adam/graphics/images/en/19917.jpg http://activebodyreadymind.com/images/Nerve.jpg cooper&part=A1967&rendertype=figure&id=A1982 http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book= http://www.rush.edu/rumc/images/ei_0062.gif

Cell Cycle Regulation continued . . . Cells that do not need to grow and divide can enter G0 (resting) until they are needed.

Regulation Cells have both internal and external regulators. Are all of the chromosomes attached to spindle fibers and properly aligned on the metaphase plate? Internal regulators—are called cyclins and are a family of proteins that make sure the cell is ready at certain checkpoints . . . If not, stops the cycle (see diagram) Is the cell big enough? Has all of the DNA duplicated completely or properly? Is the cell big enough?

Regulation continued . . . External regulators— are called growth factors. If cells are touching other cells = no growth If space with no neighboring cells = grow/divide Density-dependent inhibition http://media.pearsoncmg.com/bc/bc_campbell_concepts_5/media/art/ch8/ir/imagelib_tab_1/33.htm

Cancer What happens if cells LOSE the ability to CONTROL the cell cycle? Cancer http://www.yourcancertoday.com/ContentResources/Image/growth.jpg

Cancer Cancer = uncontrolled cell growth . . . cancer cells do NOT respond to regulator signals . . . results in masses of cells called tumors . . . cancer = a disease of the cell cycle http://www.youtube.com/watch?v=LEpTTolebqo&feature=related