Genetic Misconceptions: Difference between revisions
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The misconception regarding the influence of a dominant allele over a recessive allele in the expressed [[phenotype]] is stated as follows: ''A dominant trait is stronger and overpowers the recessive trait''. In reality, both alleles contribute to the expressed phenotype. Depending on the analogous allele it is paired up with, an allele can be phenotypically be dominant, codominant, or recessive. This can be seen when looking at the alleles that code for the [[antigens]] on the surface of [[red blood cells]]. The table below shows how the A-type allele’s “dominance-recessive” label is dependent upon the corresponding allele it is paired up with. |
The misconception regarding the influence of a dominant allele over a recessive allele in the expressed [[phenotype]] is stated as follows: ''A dominant trait is stronger and overpowers the recessive trait''. In reality, both alleles contribute to the expressed phenotype. Depending on the analogous allele it is paired up with, an allele can be phenotypically be dominant, codominant, or recessive. This can be seen when looking at the alleles that code for the [[antigens]] on the surface of [[red blood cells]]. The table below shows how the A-type allele’s “dominance-recessive” label is dependent upon the corresponding allele it is paired up with. |
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[[Image:A-allele_table.JPG]] |
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It is also a misconception to think that ''dominant and recessive traits are the norm''. Incomplete dominance is twice as prevalent as complete dominance. Less than one third of human clinical genetic conditions follow the dominant-recessive pattern. And only seven out of twenty-two traits in [[Mendel]]’s peas exhibited clear dichotomous phenotypes. |
It is also a misconception to think that ''dominant and recessive traits are the norm''. Incomplete dominance is twice as prevalent as complete dominance. Less than one third of human clinical genetic conditions follow the dominant-recessive pattern. And only seven out of twenty-two traits in [[Mendel]]’s peas exhibited clear dichotomous phenotypes. |
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Revision as of 23:51, 28 August 2006
Misconceptions about the Transmission and Expression of Hereditary Information
Science misconceptions occur when someone’s idea about a scientific concept or phenomena differ from what is scientifically accepted. Misconceptions flourish in the area of hereditary information (misconceptions are italicized).
A common misconception is that a gene and allele are different entities. Work and research in the fields of biochemistry, molecular biology, and genetics has shown that a gene can present several forms, and it is these forms that are labeled as alleles.
Another misconception concerns the hereditary information contained in a cell. Individuals mistakenly think as a zygote divides and differentiates that inheritance information segregates to new cells according to their future function. This can lead one to a supplemental misconception that asserts every cell of an organism carries only the hereditary information it needs for the specific functions it carries out. In actuality, every cell contains the same inheritance information as the zygote, even after differentiation. All cells from an individual organism carry the same genetic information.
The misconception regarding the influence of a dominant allele over a recessive allele in the expressed phenotype is stated as follows: A dominant trait is stronger and overpowers the recessive trait. In reality, both alleles contribute to the expressed phenotype. Depending on the analogous allele it is paired up with, an allele can be phenotypically be dominant, codominant, or recessive. This can be seen when looking at the alleles that code for the antigens on the surface of red blood cells. The table below shows how the A-type allele’s “dominance-recessive” label is dependent upon the corresponding allele it is paired up with.
It is also a misconception to think that dominant and recessive traits are the norm. Incomplete dominance is twice as prevalent as complete dominance. Less than one third of human clinical genetic conditions follow the dominant-recessive pattern. And only seven out of twenty-two traits in Mendel’s peas exhibited clear dichotomous phenotypes.
Bibliography
Allchin, D. (2005). The dilemma of dominance. Biology and Philosophy. Pages 427-451.
Alparslan, C., Geban, O., Tekkaya, C. (2003) Using the conceptual change instruction to improve learning. Journal of Biological Education, 37(3), Pages 133-137.
Aznar, M.M., Orcajo, T.I. (October 2005). Solving Problems in Genetics II: Conceptual restructuring. International Journal of Science Education, 27(12), Pages 1495-1519.
Banet, E., Ayuso, E., (2000). Teaching genetics at secondary school: a strategy for teaching about the location of inheritance information, Science Education, (84)3, Pages 313-351.
Rodgers, J. (1991) Mechanisms Mendel never knew. Mosaic 22(3): 2 11.