What Is Mutation? What Is a Gene Mutation? Discuss Sickle Cell Anemia (Its Cause, Effect, and Treatment) B) What Are Mutagens and Their Effects? C) What Is Genetic Counseling? Discuss the Advantages and Disadvantages of This Procedure.

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A mutation can simply be put as abrupt change in the genotype of an organism that is not the result of recombination. A gene mutation is a permanent change in the DNA sequence that makes up a gene. Mutations range in size from a single DNA building block (DNA base) to a large segment of a chromosome. Gene mutations occur in two ways: they can be inherited from a parent or acquired during a person's lifetime. Mutations that are passed from parent to child are called hereditary mutations or germ line mutations (because they are present in the egg and sperm cells, which are also called germ cells). This type of mutation is present throughout a person's life in virtually every cell in the body. Mutations that occur only in an egg or sperm cell, or those that occur just after fertilization, are called new (de novo) mutations. De novo mutations may explain genetic disorders in which an affected child has a mutation in every cell, but has no family history of the disorder. Acquired (or somatic) mutations occur in the DNA of individual cells at some time during a person's life. These changes can be caused by environmental factors such as ultraviolet radiation from the sun, or can occur if a mistake is made as DNA copies itself during cell division. Acquired mutations in somatic cells (cells other than sperm and egg cells) cannot be passed on to the next generation. Mutations may also occur in a single cell within an early embryo. As all the cells divide during growth and development, the individual will have some cells with the mutation and some cells without the genetic change. This situation is called mosaicism. Sickle cell disease is an inherited condition that is most common among people whose ancestors come from Africa, the Middle East, the Mediterranean basin, and India. In the U.S., it affects primarily African Americans, about 0.3% who have some form of sickle cell disease, and approximately 10% of whom carry the sickle cell trait. There are approximately...
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