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This 4 page Class Notes was uploaded by Sydney Thornton on Tuesday February 9, 2016. The Class Notes belongs to 1014-004 at Arkansas Tech University taught by Blake Whitt in Winter 2016. Since its upload, it has received 34 views. For similar materials see Intro to biological sciences in Biology at Arkansas Tech University.
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Date Created: 02/09/16
Chapter 5 Cancer Cancer o Disease of uncontrolled cell growth o Caused by genetic mutations that regulate cell division CASE STUDY: XERODERMA PIGMENTOSUM o Jeff age 13, has melanoma; he was diagnosed with xeroderma pigmentosum and extreme sensitivity to UV light. o XP is genetic. o Normal cells repair DNA damage due to UV rays; however, the repair is faulty. Tumor Formation o Benign tumors (noncancerous) do not spread. o Malignant tumors occur when uncontrolled cell division spreads which results in cancer. Mitosis and Cancer o Malignant cells typically have 3 common traits: Outofcontrol mitosis Greatly altered/damaged DNA Missing adhesion proteins Health Consequences of Tumor Growth o Tumor grows and impairs organ function. o Metastasis: cancer cells enter the bloodstream producing secondary tumors. o Angiogensis: blood vessels are routed to the tumor, depriving normal cells of oxygen. How do cancer cells differ from normal cells? o Normal cells Use chemical signals to control cell division and death Stop dividing at a certain density Cell division is regulated o Cancer Cells Lack effective communication Keep dividing regardless of density Are not programmed to die Molecules that regulate cell division o Growth factors bind to receptors on the cell o Activate signal transducers to relay information o Activate transcription factors to regulate gene activity. What is the life cycle of the cell o Cancer cells have defects in communication: Signal molecules Receptors that bind these signals Abnormal genes In Cancer Cells… o Receptors may be permanently activated o Signal transducers may be stuck in an activated state o Transcription factors may be produced even if preceding steps are absent o Signals that trigger apotosis are ignored. The Cell Cycle o Interphase o G1 o S o G2 o Mitosis Checkpoints in Cell Cycle o Checkpoints regulate the timing of cell division o G1 & 2 are checkpoints are raw materials available? o M checkpoint are chromosomes aligned? o Cancer cells ignore checkpoints. In what ways is cancer a genetic disorder? o Mutated DNA is passed to daughter cells o Mutations can alter cell division o If DNA doesn’t repair itself mutations accumulate o Genetic mutations can increase the risk of cancer Oncogenes o Protooncogenes regulate cell division o Mutations result in oncogenes which remain turned “on” resulting in uncontrolled division. Tumor Suppressor Genes o Encode for proteins that halt cell division o Mutations alter TSG’s, releasing the brake. o In leukemia the TSGNF 1 is mutated resulting in uncontrolled cell proliferation. Chromosomal Abnormalities o Parts of chromosomes can break, rearrange or become lost. o May turn on oncogenes or disable TSGs. What risk factors are associated with cancer? o Atleast 2/3 cancers are influenced by factors we can control: Smoking and substance abuse Diet and exercise Excessive exposure to UV o Factors outside of our control: Infections Exposure to carcinogens and polluntants Smoking o Ernest Wynder study: cigarette smokers are 40x more likely to develop lung cancer. o 8090% of lung cancer attributes are to smoking Diet and Exercise o 35% is attributed to diet. o 5% prostate and breast cancer in adults are linked to lack of exercise and excess body fat in childhood. Excessive Alcohol Use o Cancers of the mouth, throat, liver, larynx, and esophagus are associated with heavy drinking. o Smoking and Drinking increases the risk esophageal cancer up to 40x compared to nonsmoker/ nondrinker. Radiation o Exposure to UV radiation has been linked to 90% of skin cancers o Protection from sun exposure and avoiding tanning beds minimized risks. Infection o Human papillomavirus (HPV); sexually transmitted virus associated with cervical cancer. o Early detection of cervical cancer with annual Pap tests. Peyton Rous o Won the Nobel prize for his work with tumorigenic viruses. o Extracted liquid from the tumor of a chicken making sure no cells were present. o Demonstrated this was sufficient to cause cancer when injected into a healthy cancer. Workplace Carcinogens and Pollution o 5% of cancer deaths can be linked to exposure to carcinogens in the workplace. o Scientists estimate that 2% of cancers can be attributed to air, water, and soil pollution. Inheritance o 510% of cancers linked to inheritance. o Two genes can increase the risk of breast cancer: BRCA1 and BRCA2. o Woman with mutant forms have an 84% chance of developing breast cancer. Age o Mutations in DNA accumulate as you age increasing the likelihood of cancer. Poverty o Increases an individual’s risk of cancer. o Risk factors are more prevalent: Smoking, poor diet, exposure to the workplace carcinogens, exposure to infectious agents. Lack of health care, late diagnosis and expensive treatments. How is cancer diagnosed? o Blood tests o Ultrasound o Biopsy o CT scan o MRI Technology Connection: Computerized Tomography (CT) Scans o Send thin beams of Xrays at different angles to produce 3D images. o Tumors absorb more Xrays and appear darker How is cancer treated? o Surgery: localized tumors o Radiation: exposes cancer cells to Xray o Chemotherapy: drugs that inhibit cell division Cancer Treatments on the Horizon o Immunotherapy: the patient’s immune system is used to fight cancer o Angiogenesis Inhibitors: drugs inhibits growth of blood vessels, tumor unable to obtain nutrients and oxygen. Why cancer treatments sometimes fail? o As tumors proliferate mutations accumulate o New (muted) cancer cells may develop resistance to chemotherapy drugs. How can cancer be prevented? o Don’t smoke o Maintain balance, diet and exercise o Avoid excessive UV exposure Use sunscreen’ o Avoid excessive alcohol o Avoid “known carcinogens” o Get regular check ups Life Application: Chemoprevention o READ PAGE 150 BONUS for EXAM 2 o Watch “Cancer Warriors” documented by Nova Fill out worksheet on blackboard