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| A permanent change in a cells DNA; includes changes in nucleotide sequence, alteration of gene position gene loss or duplication and insertion of foreign sequences. |
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| An allele that is expressed when present in either the heterozygous or the homozygous condition. |
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| Being a homozygote, having two identical alleles of the same gene; the term is usually applied to one or more specific loci, as in "homozygoh respect to the W locus"us wit |
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| An allele that is only expressed when present in the homozygous condition, but being "hidden" by the expression of a dominant allele in the heterozygous condition. |
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| Having two different allels of the same gene; the term is usually applied to one or more specific loce, as in "heterozygous with respect to the W locus" |
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| The genetic constitution underlying a single trait or set of traits. |
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| The realized expression of the genotype; the physical appearance or functional expression of a trait. |
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| a genetic cross made to examine the distribution of one specific set of alleles in the resulting offspring. |
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| hybridization using two traits with two alleles each |
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| A mating between a phenotypically dominant individual of unknown genotype and a homozygous "tester" done to determine wheter the phonotypically dominant individual is homozygous or heterozygous for the relevant gene. |
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| A diagrammatic way of showing the possible genotypes and phenotypes of genetic crosses. |
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Term
F1 Generation
(first filial) |
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| The offspring resulting from a cross between a parental generation (P); in experimental crosses, these parents usually have different phenotypes. |
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| the parental generation in the cross pollination between two true-breeding plants that differ in a particular trait. |
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| the progeny of self-pollinated F1 generation plants. |
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| Law of Random Segregation |
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Definition
| Mendel's first law of heredity, stating that alternative alleles for the same gene segregate from each other in production of gametes. |
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| Law of Independent Assortment |
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Definition
| Mendel's second law of heredity, stating that genes located on nonhomologous chromosomes assort independently of one another. |
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| Describes a case in which two or more alleles of a gene are each dominant to other alleles but not to each other. The phenotype of a heterozygote for codominant alleles exhibit characteristics of each of the homozygous forms. Example) AA X BB = AB |
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Definition
| when there are more than two possible allele pairs for a single locus |
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| A case in which two or more allels of a gene do not display clear dominance. The phonotype of a heterozygote is intermeiate between the homozygous forms. For example, crossing red-flowered with white-flowered four o'clocks yields pink heterozygotes. |
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| Interaction between two nonallelic genes in which one of them modifies the phenotypic expression of the other. |
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| Condition in which an individual allele has more than one effect on production of the phenotype. |
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| in genetics, all of the genes on a single chromosome. They are inherited as a group; that is, during cell division they act and move as a unit rather than independently. The existence of linkage groups is the reason some traits do not comply with Mendel’s law of independent assortment (recombination of genes and the traits they control); i.e., the principle applies only if genes are located on different chromosomes. |
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| Genes that are physically close together and therefore tend to segregate together; recombination occurring between linked genes can be used to produce a map of genetic distance for a chromosome. |
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| Variation in a trait that occurs along a continuum, such as the trait of height in human beings; often occurs when a trait is determined b more than one gene. |
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| Describes a mode of inharitance in which more than one gene affects a trait such as height in human beings; polygenic inheritance may produce a continuous range of phenotypic values, rather than discrete either-or values. |
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| Hereditary blood disease in which blood clotting time is prolonged due to a lack of one vital clotting factor. It is transmitted by a sex-linked trait from females to males, appearing almost exclusively in males. |
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| A set of four phenotypes produced by different combinations of three alleles at a single locus; blood types are A, B, AB, and O, depending on which alleles are expressed as antigens on the red blood cell surface. |
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| A set of cell-surace markers (antigens) on the surface of red blood cells in humans and rhesus monkeys (for which it is named); although there are several allels, they are grouped into two main type: Rh- positive and Rh-negative. |
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