5 3 Mutations.notebook April 10, 2017

Transcription

1 Mutations Lesson 3 Mar 14 4:21 PM How can mutations affect an organism? How is cancer related to mutations and the cell cycle? Mar 14 4:22 PM 1

2 I. How can mutations affect an organism? A. Some traits are not inherited from parent organisms. Traits can also be a result of changes in the DNA * a mutation is any change in the DNA of a gene if chromosome. ex. instead of ACG, the base sequence is AAG *Mutations can cause a cell to produce an incorrect protein during protein synthesis. As a result, the organism's trait may be different from what it normally would be. Mar 14 4:23 PM * If a mutation occurs in a body cell, like a skin cell, the mutation would not be passed on to the offspring. * If the mutation occurs in the sex cell ( egg or sperm), the mutation can be passed onto the offspring and affect the offspring's traits. Mar 14 4:27 PM 2

3 B. Types of mutations Some mutations are the result of small changes in an organism's DNA ex. a base pair may be added a base pair may be substituted for another a base pair may be deleted from the DNA * These types of mutations can occur during the DNA replication process Mar 14 4:36 PM * Other mutations can occur when the chromosomes don't separate correctly * The cell can end up with too many or too few chromosomes The cell can also end up with extra segments of chromosomes Mar 14 4:39 PM 3

4 Mutations The types of mutations of DNA include deletion, addition, and substitution Mar 14 4:41 PM C. Effects of mutations Mutations introduce changes into the organism *Mutations can be helpful, harmful or neither helpful or harmful *Harmful= it reduces an organism's chances for survival and reproduction Whether a mutation is harmful or not depends partly on the organism's environment Mar 14 4:43 PM 4

5 ex. White Alligator ( page 156 in your book) In the wild, this mutation would be harmful. The white color would allow prey to easily see it making it hard to hunt. In a zoo, this mutation would not affect the organism. It is neither helpful or harmful Mar 14 4:46 PM * Helpful mutations increase an organism's ability to survive and reproduce ex. Mutations have allowed some bacteria that are harmful to humans to be resistant to drugs. The drugs do not kill the bacteria and allow it to survive and reproduce Mar 14 4:48 PM 5

6 II. How is cancer related to mutations and the cell cycle A. Cancer is more than just one disease. They are more than 100 types of cancer and they can occur in almost any part of the body * affects people world wide regardless of race, age or gender * cancers are often named after where they started in the body ex. lung cancer Mar 14 4:51 PM B. What is cancer? Cancer is a disease in which cells grow and divide uncontrollably, damaging the parts of the body around them. Like weeds in a garden that overrun the good parts and robbing them of sunlight, space and water. * cancer cells overrun normal cells Mar 14 4:58 PM 6

7 *Different factors work together in determining is a person gets cancer * Because of inherited traits, some people are more likely than others to develop certain types of cancer ex. A woman with a mother and grandmother who had breast cancer has an increased chance of developing breast cancer Mar 14 5:02 PM * Some substance in the environment may also lead to cancer ex. tar in cigarettes ultraviolet light from the sun or tanning beds people with a high fat diet may also be more likely to develop cancer Mar 14 5:04 PM 7

8 How cancer begins. Scientists think cancer begins when something damages some part of the DNA in the chromosome. The damage causes mutation and the cells function abnormally. This disrupts the normal cell cycle, causing cells to divide in an uncontrolled way. Without the normal controls, cells grow too large and divide too often Mar 14 5:06 PM How a tumor forms At first one cell develops in an abnormal way. As the cell divides over and over more abnormal cells are produced. In time these form a tumor Tumor= a mass of abnormal cells the develops when cells divide and grow uncontrollably Mar 14 5:07 PM 8

9 How cancer spreads. Tumors often take years to grow to a noticeable size. During that time, cells become more and more abnormal as they continue to divide. Some cancer cells may break off from the tumor and enter the blood stream. In this way, the cancer can spread to other areas of the body Mar 14 5:07 PM C. How Cancer is treated People with cancer undergo a variety of treatments. Treatments include surgery, radiation, and drugs that destroy the cancer cells * When cancer is detected before it has spread to other parts, surgery is usually the best treatment. * If the cells have spread or the tumor cannot be removed, doctors may use radiation * Radiation treatment uses beams of high energy waves. The beams are more likely to destroy the fast growing cells than the normal cells Mar 14 5:26 PM 9

10 * Chemotherapy is another treatment option Chemotherapy is the use of drugs to treat the disease * Cancer fighting drugs are carried throughout the body through the bloodstream *Drugs can kill cancer cells, or slow their growth *Many of these drugs, however destroy some normal cells; producing nausea or other side effects Scientists are looking for new and better ways to treat cancer. Mar 14 5:31 PM Mar 14 5:48 PM 10