Regulating the Cell Cycle cells have a “clock” with checkpoints along the way in the cell cycle chemical signals tell cells when to start and stop dividing at these checkpoints

Regulating the Cell Cycle

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Cell Cycle Checkpoints G1 Checkpoint checks growth of cell and conditions of environment if everything is good, then the cell proceeds to S phase if the cell environment does not require division, the cell may enter G0

Cell Cycle Checkpoints G1 Checkpoint G0 phase extended G1 phase cell is neither dividing nor preparing to divide some types of cells (nerve and heart muscle cells) go into G0 and continue to perform their main functions for the rest of the organism's life

Regulating the Cell Cycle

Cell Cycle Checkpoints G2 Checkpoint checks replication of chromatin and conditions of environment if everything is good, then the cell proceeds to the M phase

Regulating the Cell Cycle

Regulating the Cell Cycle M Checkpoint checks if chromosomes are properly aligned during metaphase if everything is good, then the cell completes cell division

Regulating the Cell Cycle

Why is regulating the cell cycle necessary? if problems with DNA are caught, the cell cycle is halted and the cell attempts to: correct the issue complete DNA replication repair the damaged DNA complete apoptosis

Apoptosis programmed cell death if cells are stressed due to the environment or have a genetic mutation in the DNA, a sequence of self-destruction is initiated “Cell Suicide” one cell dying may save the rest of the organism

Regulating the Cell Cycle

Cell Cycle Genetic Signals the cell cycle has built-in genetic signals to tell cells when to start and stop dividing proto-onco genes – genes that encourage cell division tumor suppressor genes – genes that inhibit cell division

Cancer a disorder in which some cells lose the ability to control their own growth these cells divide uncontrollably resulting in a tumor tumor – an abnormal growth of tissue, not necessarily cancerous

Cancer involves a loss of control over the cycle, malfunction of the “brakes” the malfunction is caused by a mutation to proto-onco genes and tumor suppressor genes (usually multiple mutations) Mutation – a change in a cell’s genes (DNA) Oncogenes – mutated proto-onco genes that stimulate excessive division

Cancer

Cancer Cancer and metastasis

Lymphatic System a network of lymph vessels and lymph nodes that is a part of the body’s immune system collects fluid, waste material, and other things (like viruses and bacteria) that are in the body tissues lymph vessels are a lot like the veins that collect and carry blood through the body but instead of carrying blood, these vessels carry a clear watery fluid called lymph

Lymphatic System

Lymph Nodes and Cancer when cancer cells break away from a tumor, they can travel to other areas of the body through either the bloodstream or the lymph system cancer in lymph nodes MAY be a sign that the cancer has spread (or could spread) through the lymphatic system to other parts of the body

Metastasis spreading of cancer from one area of the body to another typically spreads through blood or lymph

Cancer and Cell Functions uncontrolled division can compromise the function of the tissue where the dividing cells are located and ultimately may cause death quickly-dividing cells spend a large amount of time in M phase cells perform most of their normal functions while in interphase (G1)

Other Resources Pg 126-127 in your textbook National Institutes of Health (see “Related Links” sections also…) National Cancer Institute