Usher Syndrome. What Causes It. How It Happens

Essay by sneaker101Junior High, 9th gradeB+, May 2010

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Anika Lynch

Block 1

April 29, 2010

What is a DNA Mutation?

In order to know what a DNA mutation is, one must first know what is DNA. DNA, also known as deoxyribonucleic acid, is a molecule that makes up chromosomes in the cell nucleus. It is made of four bases adenine (A), thymine (T), guanine (G), and cytosine (C). Adenine and thymine always bond together and guanine and cytosine always bond together. The other thing someone should know is what mutation means. A mutation is a change or alteration. Now that you what DNA and mutation are, it is easier to figure out that a DNA mutation is a change in one of the DNA letters which make up a gene.

What Causes DNA Mutations?

DNA mutations can occur in many ways. Sometimes there can be a copying error when the DNA is replicated during cell division.

Sometimes the copy is not quite perfect. That small difference from the original DNA sequence is a mutation. Mutations can also occur from outside sources, such as viruses, radiation, and other environmental damages. Exposure to chemicals and radiation cause the DNA to break down therefore it might not do a perfect job of the repair. So the cell would end up with DNA slightly different than the original DNA resulting in a mutation. Age is also a factor when it comes to DNA mutations. As we age, DNA repairs begin to work inefficiently causing many changes in our DNA.


Usher Syndrome

Usher syndrome is a relatively rare genetic disorder that is a leading cause of deafblindness, a condition of little or no useful sight and little or no useful hearing. It is caused by a mutation in any one of 10 genes. Other names for Usher syndrome include...