Chapter 8.7-8.9 Student

8.7 Anchorage, cell density, and chemical growth factors affect cell division The cells within an organism’s body divide and develop at different rates. Cell division is controlled by the presence of essential nutrients, growth factors, proteins that stimulate division, VEGF: vascular endothelial growth factor density-dependent inhibition, in which crowded cells stop dividing, and anchorage dependence, the need for cells to be in contact with a solid surface to divide. © 2012 Pearson Education, Inc. 2

Anchorage Single layer of cells Removal of cells Restoration of single Figure 8.7B Anchorage Single layer of cells Removal of cells Figure 8.7B An experiment demonstrating density-dependent inhibition, using animal cells grown in culture Restoration of single layer by cell division 3

8.8 Growth factors signal the cell cycle control system The cell cycle control system is a cycling set of molecules in the cell that triggers and coordinates key events in the cell cycle. Checkpoints in the cell cycle can stop an event or signal an event to proceed. © 2012 Pearson Education, Inc. 4

8.8 Growth factors signal the cell cycle control system There are three major checkpoints in the cell cycle. G1 checkpoint allows entry into the S phase causes the cell to leave the cycle, entering a nondividing G0 phase. G2 checkpoint, and DNA replicated? Damaged? M checkpoint. Chromatids attached to spindles? © 2012 Pearson Education, Inc. 5

G1 checkpoint G0 G1 S Control system M G2 M checkpoint G2 checkpoint Figure 8.8A G1 checkpoint G0 G1 S Control system M Figure 8.8A A schematic model for the cell cycle control system G2 M checkpoint G2 checkpoint 6

G1 checkpoint Receptor protein S G1 Control system M G2 Figure 8.8B EXTRACELLULAR FLUID Plasma membrane Growth factor Relay proteins G1 checkpoint Receptor protein Signal transduction pathway S G1 Control system Figure 8.8B How a growth factor signals the cell cycle control system M G2 CYTOPLASM 7

8.9 Cancer: Out of control cell division Transformation Cancer cells escape controls on the cell cycle. © 2012 Pearson Education, Inc. 8

8.9 Cancer: Out of control cell division Transformation Cancer cells escape controls on the cell cycle. © 2012 Pearson Education, Inc. 9

8.9 Cancer: Out of control cell division Cancer cells divide rapidly, often in the absence of growth factors, spread to other tissues through the circulatory system, and grow without being inhibited by other cells. Form tumors Benign Malignant, metastasis

Lymph vessels Blood vessel Tumor Tumor in another part of the body Figure 8.9 Lymph vessels Blood vessel Tumor Tumor in another part of the body Glandular tissue Figure 8.9 Growth and metastasis of a malignant (cancerous) tumor of the breast Growth Invasion Metastasis 11

8.9 Cancer: Out of control cell division Cancers are named according to the organ or tissue in which they originate. Carcinomas arise in external or internal body coverings. Ex. Skin lining of intestine Sarcomas arise in supportive and connective tissue. Ex. Bone and muscle Leukemias and lymphomas arise from blood-forming tissues. © 2012 Pearson Education, Inc. 12

8.9 Cancer: Out of control cell division Cancer cells are immortal. Cancer treatments Surgery Radiation Chemotherapy is used for metastatic tumors. Taxol (yew) freezes mitotic spindle Vinblastin (periwinkle) mitotic spindle does not form © 2012 Pearson Education, Inc. 13