VIEWS: 107 PAGES: 13 POSTED ON: 7/28/2011
MUTATIONS What is Mutation? Mutation is a change in a gene/chromosome due to an error in meiosis or mitosis/ due to an environmental factor. What causes DNA mutations? Change in a gene/chromosome X-ray Chemical Nuclear radiation Ultraviolet light A condition caused by mutations in one or more genes is called a genetic disorder. A genetic disorder is a disease that is caused by an abnormality in an individual’s DNA. Abnormalities can range from a small mutation in a single gene to the entire chromosome. Effects of Mutations Source of genetic variety Some mutations are harmful, some are helpful, and others are neither harmful nor helpful. A mutation is harmful to an organism if it reduces the organism’s chance for survival and reproduction. Causes of Mutations Albinos (having pale and colorless skin) Fruit flies have legs in place of antennas. Double mutant (snake that is both albino and has 2 heads) People who completely covered in a fur- like coat of hair. Newborn babies with extended tailbone/sixth fingers. Causes of Mutations Turner Syndrome Clover which has 4 leaves Down Syndrome Sickle Cell Disease Colon Cancer/breast cancer/ovarian Alzheimer’s disease Mutations in multiple genes often coupled with environmental causes Colon cancer, breast/ovarian cancer, Alzheimer’s disease Chromosome Abnormalities Down Syndrome (extra copy of chromosome 21) Turner Syndrome (missing one X chromosome) Single gene disorder Sickle cell disease For e.g. blood contains RBC that transport oxygen around our bodies. The cells use a protein called “hemoglobin” to capture and carry the oxygen. Of our 35,000 genes, only a few contain the instruction for making hemoglobin proteins. If our hemoglobin gene is normal, the hemoglobin protein works fine. But if the instruction in that gene are changed/mutated, changes in the hemoglobin protein could result. One such mutation causes a disorder called sickle cell anemia. Helpful mutations/beneficial mutations These mutations lead to new versions of proteins that help an organism and its future generations better adapt to changes in their environment. E.g. changes in butterflies color, making it harder for predators to see it.