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Questions and Answers
In Labrador coat color inheritance, what genotypes will result in a yellow coat color, regardless of the B/b alleles?
In Labrador coat color inheritance, what genotypes will result in a yellow coat color, regardless of the B/b alleles?
- bbEE
- BBEE
- Bbee
- bbee (correct)
A breeder crosses two Labrador retrievers with the genotypes BbEe and Bbee. What is the expected phenotypic ratio of their offspring?
A breeder crosses two Labrador retrievers with the genotypes BbEe and Bbee. What is the expected phenotypic ratio of their offspring?
- 12 black : 3 chocolate : 1 yellow
- 9 black : 3 chocolate : 4 yellow
- 3 black : 1 chocolate
- 1 black : 1 chocolate : 2 yellow (correct)
A black Labrador (BBEe) is crossed with a yellow Labrador (bbee). What is the probability of producing a chocolate Labrador?
A black Labrador (BBEe) is crossed with a yellow Labrador (bbee). What is the probability of producing a chocolate Labrador?
- 0% (correct)
- 75%
- 50%
- 25%
In horses, white coat color is epistatic to black and chestnut. A horse with genotype WwBb is crossed with a horse with genotype wwBb. What proportion of offspring will have a colored coat?
In horses, white coat color is epistatic to black and chestnut. A horse with genotype WwBb is crossed with a horse with genotype wwBb. What proportion of offspring will have a colored coat?
A double heterozygous stallion (WwBb) is mated with four mares of the same genotype. If they produce 32 foals, approximately how many are expected to be white?
A double heterozygous stallion (WwBb) is mated with four mares of the same genotype. If they produce 32 foals, approximately how many are expected to be white?
Considering the Labrador retriever example, what type of genetic interaction best describes how the 'e' allele affects coat color?
Considering the Labrador retriever example, what type of genetic interaction best describes how the 'e' allele affects coat color?
A chocolate Labrador male is crossed with a yellow Labrador female, and all F1 offspring are black. Which statement accurately describes the genotypes of the parental generation?
A chocolate Labrador male is crossed with a yellow Labrador female, and all F1 offspring are black. Which statement accurately describes the genotypes of the parental generation?
If two black Labrador retrievers (BbEe) are mated, what proportion of their offspring will be chocolate?
If two black Labrador retrievers (BbEe) are mated, what proportion of their offspring will be chocolate?
In a genetic system where gene A exhibits dominant epistasis over gene B, what phenotypic ratio is expected in the F2 generation from a dihybrid cross?
In a genetic system where gene A exhibits dominant epistasis over gene B, what phenotypic ratio is expected in the F2 generation from a dihybrid cross?
Considering a scenario where two genes interact, and one gene's alleles can suppress the expression of another gene, this interaction is known as:
Considering a scenario where two genes interact, and one gene's alleles can suppress the expression of another gene, this interaction is known as:
Flashcards
Gene Interaction
Gene Interaction
Interaction between two or more pairs of different allelic genes in determining a single characteristic.
Dominant Epistasis
Dominant Epistasis
A dominant gene that masks the expression of other genes.
Recessive Epistasis
Recessive Epistasis
When homozygous recessive alleles mask the expression of other genes.
Dominant 'B' gene in Labs
Dominant 'B' gene in Labs
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Recessive 'b' gene in Labs
Recessive 'b' gene in Labs
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Dominant 'E' gene in Labs
Dominant 'E' gene in Labs
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Recessive 'e' gene in Labs
Recessive 'e' gene in Labs
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Study Notes
- Gene interaction happens when two or more pairs of different allele genes associate in determining a single trait.
Labrador Coat Color Transmission
- Phenotypes include black, chocolate, and yellow.
- Genotypes include BBEE, BbEE, BBEe, BbEe (black); bbEE, bbEe (chocolate); and Bbee, BBee, bbee (yellow).
Genetic Information
- B is the dominant gene responsible for black coat color.
- b is the recessive gene responsible for brown coat color.
- E is the dominant gene that promotes pigment deposition in the coat, allowing the color to manifest.
- e is the recessive gene that blocks pigment deposition.
- Animals that are homozygous recessive (ee) for color deposition will exhibit a yellow phenotype (without pigmentation), regardless of the other gene pair.
- This is recessive epistasis.
Dominant Epistasis
- Dominant epistasis occurs when one gene is sufficient to prevent the manifestation of the characteristic coded by another pair.
Example problem #1
- Color determination in horses (white, brown, and black) occurs through a dominant epistatic process; the W gene inhibits color manifestation.
- The B gene determines black coats; its recessive allele determines brown coats.
Example problem #2
- Crossing a chocolate phenotype male Labrador with a yellow phenotype female produces only black coated offspring (F1 generation).
- All offspring in this cross are heterozygous, while the parents are homozygous for both pairs of genes.
- Crossing the parental female with any black-coated dog is not expected to produce chocolate phenotype offspring.
- Crossing the yellow female with one of its F1 offspring is expected to produce 50% of the offspring with a yellow coat.
- Crossing F1 offspring with each other is expected to produce 25% of the offspring with a chocolate coat.
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