REGULATING the CELL CYCLE http://www.travel-net.com/~andrews/images/animations/traffic.gif

Control of Cell Division Section 10-3 If center cells are removed, cells near the space will start to grow again. SHOWS: Cell division genes can be turned on and off Cells grow until they touch other cells

CELL DIVISION GENES EXAMPLE: Cell division genes can be ________ in case of injury. Cells near injury are stimulated to divide to heal and replace damaged/missing cells and shut off when the repair has been made. turned on

CELL DIVISION GENES Some cells divide frequently (some human skin cells divide once/hour) Some cells divide occasionally (liver cells divide about once/year) Some cells don’t divide once they form (nerve cells)

CELL CYCLE REGULATORS In early 1980’s scientists discovered a protein in dividing cells that caused a ______________to form in _______________ cells Mitotic spindle NON-dividing Pearson Education Inc; Publishing as Pearson Prentice Hall

CELL CYCLE REGULATORS Levels of this protein rose and fell with the cell cycle so it was named __________ because it seemed to control the cell cycle. A whole family of CYCLINS have since been discovered that regulate the _____________________ in EUKARYOTIC CELLS CYCLIN TIMING of CELL CYCLE Pearson Education Inc; Publishing as Pearson Prentice Hall

OTHER REGULATORS INTERNAL ______________ REGULATORS Proteins that respond to events inside the cell. Allow cell cycle to proceed only if certain processes have happened EX: Cell can’t enter mitosis until all the chromosomes have been copied

OTHER REGULATORS EXTERNAL ______________ REGULATORS Proteins that respond to events outside the cell. Signals tell cell to speed up or slow down the cell cycle EX: Growth factors stimulate cells to divide Especially important during wound healing and embryo development http://www.suite101.com/files/topics/6234/files/tail_HumanTail.gif

EXTERNAL REGULATORS Molecules on the surface of neighboring cells act as signals to slow down or stop the cell’s cycle. These signals prevent excessive growth and keep tissues from disrupting each other. Pearson Education Inc; Publishing as Pearson Prentice Hall

Cancer cells have lost control of their cell division genes SEM Image by: Riedell CHO (Chinese Hamster Ovary) cells in culture

NO CONTACT INHIBITION Cancer cells don’t stop when they touch nearby they just keep growing! That’s what makes a tumor. See a video http://www.exn.ca/news/images/2000/08/02/20000802-cancer.jpg

Cancer cells Carcinogens Don’t stop dividing Like a “car with no brakes” Can spread to new places (METASTASIS) ______________ are substances that can damage DNA and cause cancer Ex: Cigarette smoke (OR CHEW), Radiation, chemicals in environment, even viruses, Carcinogens http://www.dfci.harvard.edu/abo/news/publications/pop/fall-winter-2004/images/metastasis_1.jpg

Cancer cells Cancer is complicated and can have many causes, but all cancers have one thing in common . . .… They have lost control over their _____________. Many cancers cells have a damaged or defective gene called _____, so they can’t respond to normal cell signals to control their growth. CELL CYCLE p53

UNCONTROLLED CELL GROWTH Cancer-disorder in which some of the body’s own cells lose the ability to control growth Cancer cell do not respond to the signals that regulate the growth of most cells, the divide uncontrollably and form masses of cell called tumors that can damage, surrounding tissue Two types of tumors Benign-Does not spread to surrounding tissue (non-cancerous) Malignant-spreads and destroys healthy tissue (cancerous)

CANCER CONTINUED Causes Biological Agent-Viruses Chemical Agent-Carcinogens-tobacco Physical Agent-radiation *Treatments * Surgery * Radiation * Chemotherapy-aimed at fast growing cells

How Cancer Begins Page 12 Changes in genes that influence the cell cycle can cause the transformation of a normal cell into a cancer cell. Two types of these genes The first type codes for proteins that stimulate cell division; these are usually turned-off in non-dividing cells They become ONCOGENES (cancer gene) by mutation A common oncogene, ras, is present in mutated form in about 30 % of human cancers and in some forms of leukemia 16

Page 12 Continued The second type of gene associated with cancer is a TUMOR SUPPRESSOR GENE These code for proteins that normally restrain cell division In cancer tumor suppressor genes have been inactivated by mutation An inherited mutation in one copy of a tumor suppressor gene results in higher risk of cancer 17

Page 12 Continued Almost 50% of human cancers are associated with a mutation in the tumor suppressor gene p53 P53 protein normally acts as an emergency brake in the cell cycle, but when mutated does not prevent unchecked cell division Cancers include breast, colon, lung, prostate, and skin 18

Surviving Cancer Page 13 In the United States, about one of every five deaths-more than half a million each year-are caused by cancer. (Only heart disease kills more) Lung cancer is the number one cancer killer Colorectal, breast and prostate are the next most common Cancer survival is measured by the percentage of cancer patients who survive a specific number of years. 19

Page 13 Continued Cancer survival is influenced by the type of cancer and by the stage at which a cancer is diagnosed Cancers range from Stage 1, early onset of cancer to Stage 4, the most advanced cancer EX: Colorectal cancer Stage 1, 5-yr survival rate is 96%; Stage 4 colorectal cancer 5-yr survival rate is 5% Pancreas cancer 5-yr rate is only 4% All cancers have a 64% 5-yr survival rate 20

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SOUTH DAKOTA CORE SCIENCE STANDARDS LIFE SCIENCE: Indicator 1: Understand the fundamental structures, functions, classifications, and mechanisms found in living things 9-12.L.1.1. Students are able to relate cellular functions and processes to specialized structures within cells. Cell life cycles (ANALYSIS) Examples: somatic cells (mitosis)

Core High School Life Science Performance Descriptors High school students performing at the ADVANCED level: predict the function of a given structure; predict the outcome of changes in the cell cycle; PROFICIENT level: describe the relationship between structure and function compare and contrast the cell cycles in somatic and germ cells; BASIC level recognize that different structures perform different functions describe the life cycle of somatic cells;