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What are the two main sources of genetic variation?

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Quick Answer

The two main sources of genetic variation are mutations and recombinations of genes as a result of sexual reproduction. A mutation is a permanent change in the DNA within a gene.

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Some mutations, which affect all cells in an organism, are inherited from a parent. Other mutations develop during an organism's life and occur in only some cells. Mutations are not always harmful. For instance, although the disease sickle cell anemia is caused by a mutation, that modified DNA also helps prevent malaria in some people.

Sexual reproduction causes genetic variation because of three factors. During the cell division that produces eggs and sperm, genetic material is exchanged. When these sex cells are formed, chromosomes are assorted by chance. In addition, a random egg and sperm combine during fertilization.

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Related Questions

  • Q:

    What is the significance of mutations to living things?

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    Mutations in an individual or population are necessary for adaptation to the environment, which is the driving force behind evolution. Without natural mutations, living organisms would not progress or evolve as a population in response to variable environmental stimuli.

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  • Q:

    What are examples of chromosomal mutations?

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    Some examples of chromosomal mutations are a change of pigment in flowers and change of fur patterns in mammals compared to general population, and sickle cell anemia and cystic fibrosis in humans. On the level of a DNA molecule, examples of chromosomal mutations are substitution, insertion, deletion and frameshift.

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  • Q:

    How are mutations passed on to offspring?

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    The NIH Genetics Home Reference Handbook explains that mutations are passed to offspring if these mutations are present in germ line (sperm or egg) cells. Germ line mutations can occur early in the parent's development so that they affect all of the cells in the parent's body, including eventual gametes. These mutations can also occur in gametes alone and therefore only affect offspring.

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  • Q:

    What are the effects of mutations in the MTHFR gene?

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    Mutation of the MTHFR gene causes hyperhomocysteinemia, a build-up of homocysteine in the blood, explains the U.S. National Library of Medicine. It can also cause neural tube birth defects like anencephaly, in which parts of the brain, skull or spinal cord are missing or malformed; spina bifida, in which defective vertebra expose the spinal cord; and cleft lip or palate.

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