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25 Cards in this Set
- Front
- Back
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P1
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parental generation; true-breeding strains
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F1
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offspring of P1; hybrids
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F2
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offspring of F1
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Gene
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A DNA segment coding for a particular protein, and ultimately, a particular trait
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Allele
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an alternative form of a gene
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Locus
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place on the chromosome (DNA strand) where a particular gene is found
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phenotype
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the observable, expressed trait
physical features |
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genotype
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the genetic make-up of an organism; the alleles the organism carries
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homozygous
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alleles are the same (AA or Aa)
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Heterozygous
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alleles are different (Aa)
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Dominant
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if present, this allele will mask the other allele
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Recessive
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if present, it will be maksed by the dominant allele (though if two recessive alleles are present, the recessive phenotype will be seen)
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Autosomes
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All of the chromosomes except the pair of sex chromosomes
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Sex chromosomes
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the X and Y chromosomes (determines if organism is male-XY or female-XX)
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linked vs. unlinked genes
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genes both found on the same chromosome vs. genes found on two different chromosomes
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Complete
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one allele completely masks the other
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incomplete
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both alleles are expressed, the heterozygous phenotype looks like a blending of the two homozygous phenotypes
e.g. pink snap dragon = result of red and white phenotypes |
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co-dominance
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both alleles are expressed equally; no blending
e.g. AB blood type |
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What is Mendel's Law of Assortment?
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Inheritance of one trait does not affect the probability of inheriting a second trait. This will be true as long as the genes coding for these traits are not on the same chromosome.
i.e. linked and unable to be seperated during crossover |
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What ia sex-linked gene?
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a gene that is found on the X-chromosome but not the Y
i.e. hemophelia |
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What is a sex-influenced gene?
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A gene that is found either on one of the autosomes, or on the portion of the X that has the Y counterpart
male pattern baldness |
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What is polygenic inheritance?
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A trait that is under the influence of more than one gene
often results in a gradient of phenotypes since there can be so many allele combinations skin color, height |
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What are reaction norms?
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The amount of phenotype variation that is possible when a given genotype is expressed in a given environment.
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What are Barr bodies?
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Because females recieve 2 X's, one gets shut down in every cell of the body (becomes Barr body) during embryonic development.
Which one gets shut down is random |
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What is mosaicism?
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When a female heterozygous is developing, somce cells inactivate one X chromosome, while other cells inactive the other X chromosome.
Patchy phenotype |
