Genetic mutations types

Another cumulative effect of radiation can be an irreversible alteration of DNA sequences. If part of a DNA molecule is ionized, its molecular chain may be broken. Chain breaks are repaired in the body, but after a serious rupture, the repaired unit may have a different sequence. This type of changed sequence is a genetic mutation. Altered DNA sequences in the reproductive organs are transmitted faithfully, thus passing on the genetic mutations to fiature generations. Because these effects are cumulative, individuals of childbearing age need to be especially carefial about radiation exposure. 

In recent years, a new type of genetic mutation has been discovered. The basis for this mutation is the expansion of a specific series of three nucleotides (Caskey... 

Becker J, Schwaab R, Moller-Taube A, Schwaab U, Schmidt W, Brackmann HH, Grimm T, Olek K, Oldenburg J. Characterization of the factor VIII defect in 147 patients with sporadic hemophilia A family studies indicate a mutation type-dependent sex ratio of mutation frequencies. Am J Hum Genet 1996 58(4) 657-670. 

Bacteria can obtain the various types of resistance mechanisms described previously by undergoing modifications in their genetic constitution. Many bacteria simply inherit their resistance genes from their forerunners. In addition, genetic mutations can occur that can confer a new trait. For example, it has been estimated that bacteria undergo spontaneous mutation at a frequency of approximately 1 in 10 cells. These mutations can confer resistant traits to the subsequent progeny. Mutations are believed... 

Desciibe the major types of genetic mutations that are associated with Alzheimer s disease. 

We will focus on cancer of the large bowel, rather than on revealing fragments of information on all of the major types of cancers. The incidence of cancer of the large bowel (colon and rectum) in the United States is 136,000 cases per year, while the incidence of death from colorectal cancer is about 55,000 per year (Lewis, 1996). Large bowel cancer develops with the appearance of a distinct number of genetic mutations, as do all other types of cancers. In the case of cancers of colorectal cancer, the steps tend to follow this progression ... 

Anaphylaxis in conjunction with inhibitor development has been described. Patients with hemophilia B with complete gene deletions have the greatest risk of anaphylaxis, with a minimum risk of 26%, whereas the risk in patients with null mutations was 2.4% and nearly zero for mis-sense mutations (13). Predisposing factors for the development of anaphylaxis, besides mutation type, are genetic predisposition and environmental experience, such as the type and frequency of factor IX product (13). 

HPV-16 encodes a set of early gene oncoproteins (E6 and E7) responsible for cellular immortalization. HPV types 16 and 18 E6 and E7 proteins are known to interact strongly with p53 and retinoblastoma (Rb) tumor suppressor gene products, respectively (2). The association of E6 with p53 marks this tumor suppressor for rapid ubiquitin-mediated proteolysis. Reduced levels of p53 prevent the cell from activating cell cycle arrest and/or induction of apoptosis in genetically mutated cells. 

In genetics, a type of mutation due to replacement of one nucleotide in a DNA sequence by another nucleotide or replacement of one amino acid in a protein by another amino acid. 

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