Mutations DNA: The Code of LifeDNA: The Code of Life

How Can Mutations Affect an Organism? ▪Some traits are not inherited from parent organisms. ▪Traits can also be a result of a change in DNA. ▪A mutation is any change in the DNA of a gene or chromosome.

▪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.

▪If a mutation occurs in a body cell, such as a skin cell, the mutation will not be passed on to the organism’s offspring. ▪But if a mutation occurs in a sex cell (egg or sperm), the mutation can be passed on to an offspring and affect the offspring’s traits.

Types of Mutations ▪Some mutations are the result of small changes in an organism’s DNA. ▪For example, a base pair may be added, a base pair may be substituted for another, or one or more bases may be deleted from a section of DNA. ▪These types of mutations can occur during the DNA replication process.

▪Other mutations may occur when chromosomes don’t separate correctly during the formation of sex cells. ▪When this type of mutation occurs, a cell can end up with too many or too few chromosomes. ▪The cell can also end up with extra segments of chromosomes.

Effects of Mutations ▪Mutations introduce changes in an organism. ▪Mutations can be harmful, helpful, or neither harmful nor helpful. ▪A mutation is harmful if it reduces the organism’s chances for survival and reproduction.

▪Whether a mutation is harmful or not depends partly on the organism’s environment. ▪The mutation that leads to an albino alligator’s white color would probably be harmful to it in the wild. ▪A white alligator is more visible to its prey.

▪An albino alligator may find it difficult to catch prey and may not get enough food to survive. ▪A white alligator in a zoo has the same chance for survival as a green alligator because it does not hunt. ▪In a zoo, the mutation neither helps nor harms the alligator.

▪Helpful mutations increase an organism’s ability to survive and reproduce. ▪Mutations have allowed some bacteria that are harmful to humans to become resistant to drugs. ▪The drugs do not kill the bacteria with the mutations, so they continue to survive and reproduce.

▪Effects of Mutations Lab ▪Homework is pages

How Is Cancer Related to Mutations and the Cell Cycle? ▪Cancer is not just one disease. ▪There are more than 100 types of cancer, and they can occur in almost any part of the body. ▪Cancer affects many people around the world, regardless of age, race, or gender. ▪Cancers are often named for the place in the body where they begin.

What Is Cancer? ▪Cancer is a disease in which cells grow and divide uncontrollable, damaging the parts of the body around them. ▪Cancer cells are like weeds in a garden. ▪Weeds can overrun a garden by robbing plants of the space, sunlight, and water they need. ▪Similarly, cancer cells can overrun normal cells.

▪Different factors work together in determining if a person gets cancer. ▪Because of their inherited traits, some people are more likely than others to develop certain cancers. ▪A woman with a mother or grandmother who had breast cancer has an increased chance of developing breast cancer herself.

▪Some substances in the environment may also lead to cancer, like the tar in cigarettes or ultraviolet light from the sun or tanning beds. ▪People who have a high-fat diet may also be more likely to develop cancer.

How Cancer Begins ▪Scientists think that cancer begins when something damages a portion of the DNA in a chromosome. ▪The damage causes a mutation and the cells function abnormally. ▪Normally, the cells in one part of the body live in harmony with the cells around them.

▪Cells that go through the cell cycle divide in a controlled way. ▪Cancer begins when mutations disrupt the normal cell cycle, causing cells to divide in an uncontrolled way. ▪Without the normal controls on the cell cycle, the cells may grow too large and divide too often.

How a Tumor Forms ▪At first, one cell develops in an abnormal way. ▪As the cell divides over and over more and more abnormal cells are produced. ▪In time, these cells form a tumor. ▪A tumor is a mass of abnormal cells that develops when cells divide and grow uncontrollably.

How Cancer Spreads ▪Tumors often take years to grow to a noticeable size. During that time, the cells become more and more abnormal as they continue to divide. ▪Some of the cancerous cells may break off from the tumor and enter the bloodstream. ▪In this way, that cancer can spread to other areas of the body.

How Cancer is Treated ▪People with cancer can 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 of the body, surgery is usually the best treatment. ▪If doctors can completely remove a cancerous tumor, the person may be cured. ▪If the cancer 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 cancer cells than normal cells.

▪Chemotherapy is another treatment option. ▪Chemotherapy is the use of drugs to treat a disease. ▪Many of these drugs destroy some normal cells as well, producing nausea and however, destroy some normal cells as well, producing nausea and other side affects patients often experience with chemotherpy treatments.

▪Scientists are continuing to look for new ways to treat cancer. ▪If scientists can better understand how the cell cycle is controlled, they may find ways to stop cancer cells from multiplying.

▪What Happens When There Are Too Many Cells? ▪Homework is pages