SNC2D BIOLOGY TISSUES, ORGANS & SYSTEMS OF L Cancer Cell Division Gone Wrong (P.32-34) Cancer Cell Division Gone Wrong A cell s DNA controls everything that happens in that cell, including cell division. A change in the cell s DNA can affect its cell cycle. What happens then? March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 1 Cancer Cell Division Gone Wrong Occasionally a mutation takes place in the DNA that controls the cell cycle. This can create cancer cells. Cancer is a group of diseases in which cell division is uncontrolled. CANCER group of diseases in which cell division is uncontrolled March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 2 1
Uncontrolled cell division sometimes leads to the formation of a lump or tumour. A tumour is a mass of cells that continue to divide without any benefit to the body. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 3 Tumour cells are like healthy cells. They need nutrients and oxygen to survive and to go through the cell cycle. Thus, they need access to the body s blood supply. But how does the tumour get access? March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 4 They send out chemical signals to normal cells in the surrounding area. These healthy cells respond by encouraging nearby blood vessels to expand into the tumour mass. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 5 2
PRACTICE 1. Is there anything that can be done to slow or stop the growth of a tumour? Cancer scientists around the world are working to find a way to cut off the blood supply to tumours. These scientists hope to find a chemical that will prevent the cancer cells from sending out signals that ask for nutrients. Without these signals, new blood vessels will not expand into the tumour. The tumour will not receive the nutrients it needs. It may not grow as quickly or it may even die. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 6 There are two major classes of tumours: benign and malignant. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 7 TUMOUR mass of cells that continue to divide and increase in number do not benefit the body two types: benign and malignant March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 8 3
Abenigntumour has no serious effect on the normal cells around it. The normal cells around the tumour may be crowded, but their function is unaffected. A benign cancer is not cancerous. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 9 BENIGN TUMOUR does not interfere with surrounding cells it just crowds them not cancerous March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 10 Amalignanttumour, on the other hand, interferes with the work of the cells around it or destroys those cells. Malignant tumours are cancerous. Malignant tumours are also dangerous because their cells can break away and travel to another part of the body. There, they can start a new tumour. This process is known as metastasis. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 11 4
MALIGNANT TUMOUR interferes with the work of the cells around it or destroys them are cancerous dangerous because their cells can break away and travel to another part of the body where they start a new tumour (i.e. metastasis) March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 12 Causes of Cancer The risk of getting some types of cancers like breast cancer and colon cancer appear to be genetically inherited. An inherited cancer is one that appears within members of the same family. Other forms of cancer are caused by factors in the environment, poor lifestyle choices, or viruses. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 13 Causes of Cancer A factor in the environment that causes cancer is called a carcinogen. Carcinogens take many forms. Tobacco smoke, smokeless tobacco products, X-rays, environmental pollution, UV radiation from sunlight or tanning beds, some viruses, organic solvents, and certain chemicals in plastics have all been found to cause cancer. Reducing or eliminating your exposure to these carcinogens can reduce your risk of getting cancer. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 14 5
Causes of Cancer CARCINOGEN any environmental factor that causes cancer includes: tobacco products X-rays pollution UV radiation (sun or tanning beds) chemicals March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 15 Tobacco as a Cause of Cancer Tobacco smoke contains many harmful chemicals including nicotine, hydrogen cyanide, and carbon monoxide. These chemicals damage DNA and cause tumours. Smoking is the most common cause of lung cancer among Canadians. It also causes many types of cancer throughout the body (see diagram). March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 16 Tobacco as a Cause of Cancer You can reduce your chance of getting cancer if you stop smoking or if you never start to smoke. Avoiding second-hand smoke can also help reduce your risk of getting cancer. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 17 6
Effects of Diet on Cancer A University of Toronto study has found a link between poor diet and colon cancer. If you do not eat your five to twelve servings of fruit and vegetables every day then you may be missing out on fibre, vitamins, and natural cancer-fighting compounds called antioxidants. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 18 Effects of Diet on Cancer A healthy diet including eating less red meat, processed meat, saturated fat, and refined sugar may help you reduce your risk of some cancers. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 19 UV Radiation as a Cause of Skin Cancer If you like to lie out in the sunshine for hours or use tanning beds, you should know that ultraviolet radiation (UV), a form of invisible high-energy radiation, is a leading cause of skin cancer. UV radiation (which includes UVA and UVB) causes mutations in skins cells. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 20 7
UV Radiation as a Cause of Skin Cancer UVA rays which cause the skin to tan are used in tanning beds. UVB rays cause burning and make your skin look red. Even though UVB rays do not penetrate the skin as deeply as UVA rays, they can still be damaging. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 21 UV Radiation as a Cause of Skin Cancer UVB rays are not all bad. They help your body make vitamin D. Spending a few minutes every day in the sun without sunscreen can provide your body with necessary vitamin D. However, more than a few minutes of unprotected exposure could be harmful. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 22 Causes of Cancer CAUSES OF CANCER a mutation or change in the DNA that controls cell division some seem to be inherited (breast and colon) others caused by: environmental factors (i.e. carcinogens) lifestyle choices (i.e. diet) viruses Smoking is the most common cause of lung cancer. It also causes many other types of cancer throughout your body. March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 23 8
U Check Your Learning 1. During a twenty-year period, three people in one family develop the same type of colon cancer. What might a doctor suspect about this cancer? it is hereditary March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 24 U Check Your Learning 2. Why might a person who has skin cancer later develop a tumour on her lungs? some of the cancer cells broke away and moved to the lungs (i.e. it metasized) March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 25 U Check Your Learning 3. What is the role of UV radiation in the formation of skin cancer? it causes mutations in the skin cells March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 26 9
U Check Your Learning 4. Describe some differences between a benign and a malignant tumour. benign not cancerous, doesn t move, does not harm other cells malignant cancerous, can move, harms other cells March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 27 U Check Your Learning 5. What is a carcinogen? Name three. any environmental factor that causes cancer tobacco smoke, X-rays, pollution, UV radiation, chemicals, March 24, 2013 2DBIOL - Cancer (Cell Division Gone Wrong) 28 10