Cyclins, Mutagens and Oncogenes

Learning Targets Cyclins are involved in the control of the cell cycle Mutagens, oncogenes and metastasis are involved in the development of primary and secondary tumors.

Tumors Tumors are abnormal growth of cell tissue. They are caused by uncontrolled cell division. Tumors can be benign (harmless) or malignant (harmful) Disease caused by tumors is called cancer.

Mutagens Mutagens are agents that can cause gene mutations Mutagens that lead to cancer are called carcinogens There are physical mutagens, chemical mutagens and biological mutagens Can you think of examples of each?

With your groups… You have 5 minutes to do a little research and come up with one physical mutagen, one chemical mutagen, and one biological mutagen Write your mutagens on the whiteboard when you are done

Oncogenes Genes that can become cancer-causing after mutating are called Oncogenes. In a normal cell oncogenes are involved in control of the cell cycle. Oncogenes are generally split into two classes: Proto-oncogenes- code for proteins that stimulate the cell cycle and cell growth Tumor suppressor genes- code for proteins that repress the cell cycle and promote apoptosis

DBQ on smoking

Cyclins- regulating the cell cycle The cell cycle is a complex process that involves many steps that must be performed by the cell in the correct order. Cyclins are a group of proteins that regulate a cell’s progress through the cell cycle

Cyclins Concentration G1 Phase S Phase Mitosis G2 Phase

Cyclin D- triggers cell to move from G0 to G1 and from G1 into S phase Cyclin E-prepares the cell for DNA replication in S phase Cyclin A-activates DNA replication inside the nucleus in S phase Cyclin B- promotes the assembly of the mitotic spindle and other tasks in the cytoplasm to prepare for mitosis

Benign and Malignant Tumors Cancer cells are unique from normal cells. Normal cells reach densities that limit the nutrition available for growth replication. Cancer cell have no density dependence. Normal cells have normal shapes and energy needs. Cancer cells are misshapen, usually use the fermentation pathway, and thus gobble up energy. Some tumors can even grow their own blood vessels! Normal cells must be anchored to other tissues or cells in order to complete the cell cycle. Cancer cells can metastasize (break away from the tumor and enter other tissues).

Benign and Malignant Tumors On the left, we see a benign tumor. The cell mass has grown, but is not taking over or invading surrounding tissue. On the right, we see a malignant tumor. The cells are growing and spreading into the surrounding tissue. When they reach a blood vessel and are carried to other parts of the body, it is called metastasis. The spread of cancer can be stopped if a tumor is removed before it metastasizes. After this, tumors could appear anywhere in the body that is exposed to blood flow (everywhere). This is why it is especially important to have unknown lumps checked out and removed early.