Cell Division Going Wrong: Cancer
Cancer is a group of diseases in which cells grow and divide out of control It results from a change in the DNA that controls the cell cycle. This change prevents the cells from staying in interphase for the normal amount of time. The cell and all of its subsequent daughter cells continue to divide uncontrollably. Some types of cancer run in families, whereas others are triggered by environmental factors. Some cancers may have both hereditary and environmental causes. Cancer is not infectious: you cannot catch it from someone who has it.
Cancer is a group of diseases in which cells grow and divide out of control It results from a change in the DNA that controls the cell cycle. This change prevents the cells from staying in interphase for the normal amount of time. The cell and all of its subsequent daughter cells continue to divide uncontrollably. Some types of cancer run in families, whereas others are triggered by environmental factors. Some cancers may have both hereditary and environmental causes. Cancer is not infectious: you cannot catch it from someone who has it.
Cell Growth Rates and Cancer
A cancer cell is one that continues to divide despite messages from the nucleus or the surrounding cells to stop growing and dividing. The uncontrolled growth and division may create a rapidly growing mass of cells that form a lump or tumour. The cells of the tumour may stay together and have no serious effect on surrounding tissues. This is called a benign tumour. Cells in a benign tumour are not cancerous. However, sometimes a benign tumour can grow so large that it physically crowds nearby cells and tissues. A mass of cells is a malignant tumour if it interferes with the function of neighboring cells and tissues, such as the production of enzymes or hormones. Malignant tumours may even destroy surrounding tissues. The cells in a malignant tumour are considered cancerous.In some cases, cancer cells break away from the original (primary)
tumour and move to a different part of the body. If they settle there and continue growing and dividing uncontrollably, they can start a new
(secondary) tumour. This process is known as metastasis and is one of the reasons why cancer is such a dangerous disease.
A cancer cell is one that continues to divide despite messages from the nucleus or the surrounding cells to stop growing and dividing. The uncontrolled growth and division may create a rapidly growing mass of cells that form a lump or tumour. The cells of the tumour may stay together and have no serious effect on surrounding tissues. This is called a benign tumour. Cells in a benign tumour are not cancerous. However, sometimes a benign tumour can grow so large that it physically crowds nearby cells and tissues. A mass of cells is a malignant tumour if it interferes with the function of neighboring cells and tissues, such as the production of enzymes or hormones. Malignant tumours may even destroy surrounding tissues. The cells in a malignant tumour are considered cancerous.In some cases, cancer cells break away from the original (primary)
tumour and move to a different part of the body. If they settle there and continue growing and dividing uncontrollably, they can start a new
(secondary) tumour. This process is known as metastasis and is one of the reasons why cancer is such a dangerous disease.
Causes of Cancer
Every time a cell divides, its DNA is faithfully duplicated. Usually, this process is error-free and the genetic information in the daughter cells is exactly the same as that in the parent cell. Sometimes, however, random changes occur in DNA. These random changes are known as mutations.These changes may either result in the death of the cell or allow the cell to survive and continue to grow and divide. Very rarely, the change occurs in the DNA that controls cell division. Once this crucial cell cycle DNA starts behaving abnormally, the cells may become cancerous and proliferate wildly through repeated, uncontrolled mitosis and cytokinesis. They multiply until all nutrients are exhausted. Some mutations are caused by carcinogens: environmental factors that cause cancer. Well-known carcinogens include tobacco smoke; radiation, such as X-rays and UV rays from tanning beds and sunlight; some viruses, such as human papillomavirus (HPV) and hepatitis B; certain chemicals in plastics; and many organic solvents.
Every time a cell divides, its DNA is faithfully duplicated. Usually, this process is error-free and the genetic information in the daughter cells is exactly the same as that in the parent cell. Sometimes, however, random changes occur in DNA. These random changes are known as mutations.These changes may either result in the death of the cell or allow the cell to survive and continue to grow and divide. Very rarely, the change occurs in the DNA that controls cell division. Once this crucial cell cycle DNA starts behaving abnormally, the cells may become cancerous and proliferate wildly through repeated, uncontrolled mitosis and cytokinesis. They multiply until all nutrients are exhausted. Some mutations are caused by carcinogens: environmental factors that cause cancer. Well-known carcinogens include tobacco smoke; radiation, such as X-rays and UV rays from tanning beds and sunlight; some viruses, such as human papillomavirus (HPV) and hepatitis B; certain chemicals in plastics; and many organic solvents.
Smoking and Cancer
Lung cancer is one of the most common types of cancer in Canadians over 40. According to Health Canada, smoking currently causes 9 out of 10 cases of lung cancer. Carcinogens in tobacco affect more than just the lungs. Smoking also increases the risk of over a dozen other types of cancer in the image shown.
Lung cancer is one of the most common types of cancer in Canadians over 40. According to Health Canada, smoking currently causes 9 out of 10 cases of lung cancer. Carcinogens in tobacco affect more than just the lungs. Smoking also increases the risk of over a dozen other types of cancer in the image shown.