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23 Cards in this Set
- Front
- Back
Genotype |
The genetic comparison of an organism. |
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Phenotype |
The characteristics of a organism, often visible, resulting from both its gentype and the effects of the environment. |
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Gene |
A length of DNA on a chromosome normally coding for a particular polypeptide. |
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Gametes |
Reproductive (sex) cells that fuse with another gamete during fertilisation. |
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Nucleotides |
Complex chemicals made up of an organic base, a sugar and a phosphate. |
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Alleles |
One form of a gene. |
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Dominant Alleles |
A term applied to an allele that is always expressed in the phenotype of an organism. |
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Recessive Allele |
The condition in which the effect of an allele is apparent in the phenotype of a diploid organism only in the presence of another identical allele. |
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Homozygous |
When alleles on the chromosomes are the same. |
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Heterezygous |
When the alleles on the chromosome are different from each other. |
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Co-dominant |
When two alleles both contribute to the phenotype. |
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Multiple Alleles |
When a gene has more that two allelic forms. |
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Mutation |
A change in the DNA. |
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Monohybrid Inheritance |
The inheritance of a single gene. |
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Pure-breeding |
Alleles that are homozygous dominant (GG) or homozygous recessive (gg). |
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Barr Body |
The inactive X chromosome in a female somatic cell. |
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Somatic Cell |
A normal body cell. |
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Allele Frequency |
The number of times an allele occurs within the gene pool. |
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Gene Pool |
The total number of alleles in a particular population at a specific time. |
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Directional Selection |
Selection that operates towards one extreme in a range of variation. |
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Stabilising Selection |
Selection that tends to eliminate the extremes of the phenotype range within a population. It arises when environmental conditions are constant. |
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Polygenes |
A group of genes that are responsible for controlling a characteristic. |
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Normal Distribution |
A bell-shaped curve produced when a certain distribution is plotted on a graph. |