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Mutations

2013-11-13 来源: 类别: 更多范文

Mutations Are mutations beneficial' In a living cell, DNA undergoes frequent chemical change, especially when it is being replicated. Most of these changes are quickly repaired. Those that are not result in a mutation. Mutation is a change in the genetic material that controls heredity. They can disrupt a body’s development or functioning with just a tiny change in the DNA. Thus, mutation is a failure of DNA repair. Mutations are strictly harmful and strictly helpful, depending on the environment. Most mutations are not helpful, since any change in the delicate balance of an organism having a high level of adaptation to its environment tends to be disruptive. In higher animals and many higher plants a mutation may be transmitted to future generations only if it occurs in germ, or sex cell, tissue; somatic, or body cell, mutations cannot be inherited except in plants that propagate. Sometimes the word mutation is used broadly to include variations resulting from aberrations of chromosomes; in chromosomal mutations the number of chromosomes may be altered, or segments of chromosomes may be lost or rearranged. Changes within single genes, called point mutations, are actual chemical changes to the structure of the constituent DNA. The simplest mutation mutation, change, mutations, single, dna, bicycle, one, changes, cell, because, round, nut, nucleotide, motorcycle, legs, instead, factory, chromosomes, added, take, suppose, strictly, sometimes, slight, point, plants, place, peg, out, occurs, mistake, might, make, left, instructions, improvement
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