Term
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Definition
- a heritable feature that varies among individuals
example: flower color |
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Definition
- each variant for a character
example: purple flowers or white flowers |
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Term
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Definition
- alternative versions of a gene
- variations in a gene's nucleotide sequence
example: the purple flower allele and the white-flower allele |
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Term
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Definition
- the two alleles for a heritable character separate during gamete formation and end up in different gametes
layman: the parents each pass only one allele to each offspring ... offspring inherit one allele from each parent |
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Term
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Definition
| - breeding of a recessive homozygote with an organism of dominant phenotype but unknown genotype |
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Term
| the law of independent assortment |
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Definition
- each pair of alleles segregates independently of other pairs of alleles during gamete formation
example: seed shape and seed color are not a package deal -- they sort out independently of each other
**note: this law applies only to alleles located on different chromosomes |
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Term
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Definition
- the phenotypes of the heterozygote and the dominant homozygote are identical
example: purple flowers and yellow flowers |
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Definition
- two alleles both affect the phenotype in separate, distinguishable ways
example: blood types (AA, AB, BB, OO) |
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Term
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Definition
- heterozygotes have phenotypes somewhere in between the phenotypes of the two parental varieties
example: a cross between red snapdragons and white snapdragons produce heterozygous snapdragons with pink flowers
**this is not evidence for the blending hypothesis because a cross between two pink flowers will produce a phenotypic ratio of 1:2:1 (red:pink:white) |
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Term
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Definition
- genes that have multiple phenotypic effects
examples: cystic fibrosis, sickle-cell disease, PKU |
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Term
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Definition
- a condition in which a gene at one locus alters the phenotypic expression of a gene at a second locus
example: coat color and pigment of mice |
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Term
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Definition
- the additive effect of two or more genes on a single phenotypic character
example: skin color
** the converse of pleiotropy |
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Term
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Definition
- the phenotypic range for a genotype that depends on the environment in which the genotype is expressed
-usually broadest for polygenic characters
example: hydrangea flowers of the same genetic variety range in color from blue-violet to pink, depending on the acidity of the soil
example: |
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Term
| multifactorial characters |
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Definition
| - characters that are influenced by many factors, both genetic and environmental |
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Term
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Definition
| - a familial history for a particular trait assembled into a family tree describing the interrelationships of parents and children across the generations |
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Definition
- heterozygotes (Aa) who may transmit the recessive allele to their offspring
- phenotypically normal with regard to a recessive disorder |
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Term
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Definition
- The idea that genetic material from the two
parents blends together
example: blue and yellow paint blend to make green |
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