1. By: Diana Olalde (DNA Mutations)

2.  DNA is constantly subject to mutations, accidental changes in its code. Mutations can lead to missing or malformed proteins, and that can lead to disease.

3.  These are the sickle-shaped blood cells of someone with sickle cell anemia, a genetic disease common among those of African descent.  Sickle cell anemia is the result of a point mutation, a change in just one nucleotide in the gene for hemoglobin. This mutation causes the hemoglobin in red blood cells to distort to a sickle shape when deoxygenated. The sickle-shaped blood cells clog in the capillaries, cutting off circulation.  Having two copies of the mutated genes cause sickle cell anemia, but having just one copy does not, and can actually protect against malaria - an example of how mutations are sometimes beneficial. Sickled blood cells (left) and normal blood cells.

4.  A mutation is a permanent change in the DNA sequence of a gene.

5.  We all start out our lives with some mutations. These mutations inherited from your parents are called germ-line mutations. However, you can also acquire mutations during your lifetime. Some mutations happen during cell division, when DNA gets duplicated. Still other mutations are caused when DNA gets damaged by environmental factors, including UV radiation, chemicals, and viruses.

6.  Few mutations are bad for you. In fact, some mutations can be beneficial. Over time, genetic mutations create genetic diversity, which keeps populations healthy. Many mutations have no effect at all which are called silent mutations.  But the mutations we hear about most often are the ones that cause disease. Some well-known inherited genetic disorders include cystic fibrosis, sickle cell anemia, Tay-Sachs disease, phenylketonuria and color-blindness, among many others. All of these disorders are caused by the mutation of a single gene.  Scientists estimate that every one of us has between 5 and 10 potentially deadly mutations in our genes-the good news is that because there's usually only one copy of the bad gene, these diseases don't manifest.  Cancer usually results from a series of mutations within a single cell. Often, a faulty, damaged, or missing p53 gene is to blame. The p53 gene makes a protein that stops mutated cells from dividing. Without this protein, cells divide unchecked and become tumors.

7. Everyone acquires some changes to their DNA during the course of their lives. These changes occur in a number of ways. Sometimes there are simple copying errors that are introduced when DNA replicates itself. Some of these changes occur in cells of the body such as—  In skin cells as a result of sun exposure— but are not passed on to children.  Other errors can occur in the DNA of cells that produce the eggs and sperm.  These are called germline mutations and can be passed from parent to child. If a child inherits a germline mutation from their parents, every cell in their body will have this error in their DNA. Germline mutations are what cause diseases to run in families, and are responsible for the kind of hereditary diseases covered by Genetic Health.

8.  A mutation is a change in DNA, the heredity material of life. An organism’s DNA effects how it looks, how it behaves, and its physiology. So a change in an organism’s DNA can cause changes in all aspects of its life.

9.  Single base substitutions  Insertions and deletions  Chromosomal mutations  Mutation case study : Cystic Fibrosis

10.  We can divide "repair" mechanisms into 3 categories:  damage reversal--simplest; enzymatic action restores normal structure without breaking backbone  damage removal--involves cutting out and replacing a damaged or inappropriate base or section of nucleotides  damage tolerance--not truly repair but a way of coping with damage so that life can go on

11.  http://www.thetech.org/genetics/art04_bad. php http://www.thetech.org/genetics/art04_bad. php