Biology Chapter 10 Penn Foster

Front 1

carrier

Back 1

heterozygous individual who has no apparent abnormality but can pass on an allele for a recessively inherited genetic disorder

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chromosome map

Back 2

sequence that shows the relative distance between gene loci on a chromosome

Front 3

codominance

Back 3

inheritance pattern in which both alleles of a gene are equally expressed

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dihybrid

Back 4

individual that is heterozygous for two traits; shows the phenotype governed by the dominant alleles but carries the recessive alleles

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dominant allele

Back 5

allele that exerts its phenotypic effect in the heterozygote; it masks the expression of the recessive allele

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gene linkage

Back 6

existence of several alleles on the same chromosome

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gene locus

Back 7

specific location of a particular gene on homologous chromosomes

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genotype

Back 8

genes of an organism for a particular trait or traits; often designated by letters - for example, BB or Aa

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heterozygous

Back 9

possessing unlike alleles for a particular trait

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homozygous

Back 10

possessing two identical alleles for a particular trait

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incomplete dominance

Back 11

inheritance pattern in which the offspring has an intermediate phenotype, as when a red-flowered plant and a white-flowered plant produce pink-flowered offspring

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law of independent assortment

Back 12

alleles of unlinked genes assort independently of each other during meiosis so that the gametes contain all possible combinations of alleles

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law of segregation

Back 13

separation of alleles from each other during meiosis so that the gametes contain one from each pair. Each resulting gamete has an equal chance of receiving either allele

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linkage group

Back 14

alleles of different genes that are locatedon the same chromosome and tend to be inherited together

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multifactorial trait

Back 15

trait controlled by polygenes subject to environmental influence; each dominant allele contributes to the phenotype in an additive and like manner

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phenotype

Back 16

visible expression of a genotype; ex. brown eyes or attached earlobes

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pleiotropy

Back 17

inheritance pattern in which one gene affects many phenotypic characteristics of the individual

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polygenic inheritance

Back 18

pattern of inheritance in which a trait is controlled by several allele pairs; each dominant allele contributes to the phenotype in an additive and like manner

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Punnett square

Back 19

grid used to calculate the expected results of simple genetic crosses

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recessive allele

Back 20

allele that exerts its phenotypic effect only in the homozygote; its expression is masked by a dominant allele

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recombinant gamete

Back 21

new combination of alleles incorporated into a gamete during crossing-over

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rule of multiplication

Back 22

the chance of two (or more) independent events occurring together is the product of their chance occurring separately

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testcross

Back 23

cross between an individual with the dominant phenotype and an individual with the recessive phenotype. The resulting phenotypic ratio indicates whether the dominant phenotype is homozygous or heterozygous

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wild-type

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allele or phenotype that is the most common for a certain gene in an population

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X-linked

Back 25

allele that is located on an X chromosome but may control a trait that has nothing to do with the sex characteristics of an animal