 | Term | Definition |
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Law of Segregation |
During the formation of gametes, the two traits carried by each parent separate. |
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Law of Dominance |
When 2 organisms, each homozygous (pure) for two opposing traits are crossed, the offspring will be hybrid (carrying 2 different alleles) but will exhibit only the dominant trait. |
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Law of Independent Assortment |
During gamete formation, the alleles of a gene for one trait segregate independently from the alleles of a gene for another trait. Applies only when a cross is carried out b/t 2 hybrid induviduals for 2 or more traits that are not on the same chromosome. |
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Incomplete Dominance |
A blending of traits. Ex: A white flower and red flower have pink offspring. |
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Codominance |
Expression of both traits. |
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Multiple Alleles |
Gene that exist in more than two allelic forms. |
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Pleiotropy |
The ablility of one single gene to affect an organism in several/many ways. |
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Epistasis |
When two separate genes control one trait, but one gene masks the xpression of the other gene. |
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Polygenic Inheritance |
A blending of several separate genes that vary along a continuum. Ex: skin color, hair color, height, etc. |
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Barr Body |
The dark spot of chromatin made of inactivated chromosomes that can be seen on the outer edge of the nucleus of all somatic cells in a female. |
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Deletion |
A chromosomal aberration in which a fragment lacking a centromere is lost during cell division. |
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Inversion |
A chromosomal error in which a chromosomal fragment reattaches to its original chromosome, but in a different orientation. |
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Translocation |
A chromosomal error in which a fragment of a chromosome attatches to a non homologous chromosome. |
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Polyploidy |
Chromosomal error in which a cell or organism has an extra set of chromosomes. |
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Nondisjunction |
Chromosomal error in which homologous chromosomes fail to separate during meiosis. Results in an aneuploidy (a abnormality of # of chromosomes). |
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Genomic imprinting |
phenomenon in which certain traits vary depending on which parent they are inherited from. |
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Extranuclear Genes |
genes found in mitochondria and chloroplasts. Diseases caused by these genes are always inherited from the mother and affect the organs that require the most energy to function (Nervous and Muscular system). |
