Cell Cycle and Mitosis Uncontrolled Cell Growth

 Benign Does not spread Does not spread Easily removed Easily removed  Malignant cancer Spreads to other cells and tissues Spreads to other cells and tissues Difficult to remove because it invades so may other cells Difficult to remove because it invades so may other cells

Benign Growth  Easily removed Warts Warts Polyps Polyps Benign tumors Benign tumors

Cancer  Defined as uncontrolled cell division coupled with the capacity to spread (metastasis) to other locations in the body  Cancer cells actually build new blood vessels to send blood to the center of a tumor

Testicular Cancer  The red and white areas are cancer cells.

Breast cancer  Low magnification

Skin Cancer

Lung Cancer  Healthy vs. Cancerous

Cancer cells are characterized by:  No contact inhibition cells continue to grow and divide even after contacting other cells cells continue to grow and divide even after contacting other cells  No "anchorage" dependency Does not need to be attached to anything Does not need to be attached to anything  No requirement for external growth factors Most cells rely on hormones to tell them when and how to grow. Most cells rely on hormones to tell them when and how to grow.  Failure to differentiate cells stay immature instead of changing into skin cells, heart cells, lung cells, etc. cells stay immature instead of changing into skin cells, heart cells, lung cells, etc.

Why does a cell become cancerous?  Oncogene A mutation in DNA causes the cell to continue dividing. A mutation in DNA causes the cell to continue dividing.  Tumor-Supressor gene This gene normally tells the cell to stop dividing. This gene normally tells the cell to stop dividing. In cancer cells this gene has been changed, or mutated. In cancer cells this gene has been changed, or mutated.

Treatments  Surgery removes tumors, but ineffective if the cancer has spread removes tumors, but ineffective if the cancer has spread  Radiation prevents mitosis, so cancer cells are especially vulnerable. prevents mitosis, so cancer cells are especially vulnerable. Sometimes coupled with temporary bone marrow transplants. Sometimes coupled with temporary bone marrow transplants. Ineffective if the cancer has spread, because the entire body cannot be irradiated. Ineffective if the cancer has spread, because the entire body cannot be irradiated.

Treatments cont.  Chemotherapy relies on a wide variety of drugs to find cancer cells and destroy them, or to prevent the formation of supporting tissue (e.g. new blood vessels). relies on a wide variety of drugs to find cancer cells and destroy them, or to prevent the formation of supporting tissue (e.g. new blood vessels). Unfortunately, these drugs also kill healthy cells (hair follicles and intestinal lining), producing the well- known side effects of hair loss and nausea. Unfortunately, these drugs also kill healthy cells (hair follicles and intestinal lining), producing the well- known side effects of hair loss and nausea.  Immunization once thought impossible due to diverse nature of cancer, but now there is some hope through of the action of new antibodies. once thought impossible due to diverse nature of cancer, but now there is some hope through of the action of new antibodies.

Fighting Cancer: Before  A fully intact cancer cell surrounded by the immune system’s killer t-cells.  Notice the tentacles of the cancer cell.

Fighting Cancer: After  Notice how the cancer is completely flattened and totally destroyed.  A t-cell pokes holes in the cell membrane of the cancer cell, allowing fluid and salts enter so that the target cell eventually bursts.