The term epistasis is used to refer to a situation in which the expression of a gene is influenced by another independently inherited gene. In labs, the gene B determines how much pigment is made. The dominant allele B results in black fur and the recessive allele b results in brown (chocolate) fur. A separate gene, E, codes for a protein that determines whether the pigment is deposited in the hair. (E = pigment deposited; e = pigment not deposited). What genotypes are possible for a black lab? What genotypes are possible for a chocolate lab? What genotypes are possible for a yellow Lab? In a cross between a black lab that is homozygous for both alleles and a yellow lab that is homozygous for both alleles, what would the genotype and phenotype of the offspring be? Imagine you cross two heterozygous parents. What are the genotypic and phenotypic ratios of the offspring?

The term epistasis is used to refer to a situation in which the expression of a gene is influenced by another independently inherited gene. In labs, the gene B determines how much pigment is made. The dominant allele B results in black fur and the recessive allele b results in brown (chocolate) fur. A separate gene, E, codes for a protein that determines whether the pigment is deposited in the hair. (E = pigment deposited; e = pigment not deposited). What genotypes are possible for a black lab? What genotypes are possible for a chocolate lab? What genotypes are possible for a yellow Lab? In a cross between a black lab that is homozygous for both alleles and a yellow lab that is homozygous for both alleles, what would the genotype and phenotype of the offspring be? Imagine you cross two heterozygous parents. What are the genotypic and phenotypic ratios of the offspring?

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Human Biology (MindTap Course List)

11th Edition

ISBN:9781305112100

Author:Cecie Starr, Beverly McMillan

Publisher:Cecie Starr, Beverly McMillan

Chapter19: Introduction To Genetics

Section: Chapter Questions

Problem 4CT: The young woman shown at right has albinismvery pale skin, white hair, and pale blue eyes. This...

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The young woman shown at right has albinismvery pale skin, white hair, and pale blue eyes. This phenotype is due to the absence of melanin, which imparts color to the skin, hair, and eyes. It typically is caused by a recessive allele. In the following situations, what are the probable genotypes of the father, the mother, and their children? a. Both parents have normal phenotypes; some of their children are albino and others are not. b. Both parents and all their children are albino. c. The mother is not albino, the father is albino, and one of their four children is albino.
In mice, coat color is due to the inheritance of three genes located on three different chromosomes. The A gene which determine if a yellow band is present on the hair ( A_= yellow band, aa= no yellow band ) and the B gene which determines if the hair is brown ( bb ) or Black ( B_). The A and B genes interact to produce the following coat colors: Agouti: A_B_ Cinnamon: A_bb black: aaB_ brown aabb The third gene is the C gene, which determines if the mice has any hair pigment at all. If the mouse has at least one C allele then the coat color will be determined by the A and B genes as described above. However, if the mouse is cc in genotype it will be albino, regardless of the mouse’s A and B genotype. 3. If a AabbCc mouse mates with a aaBbcc mouse, what is the probability that a mouse will be born an albino? (a) ½ (b) ¼ (c) 1/16 (d) 3/16 (e) none of the above
Marfan syndrome is a disease caused by a rare dominant allele of the fibrillin-1 gene. Fibrillin-1 is an important component of the extracellular matrix, and people with the disease-causing allele have abnormal connective tissue. An affected mother (Marta) and an unaffected father (Joe) have one unaffected daughter (Luisa - she does not exhibit any traits of the syndrome). If Luisa has a child with Nico (unaffected), what is the probability that her child will inherit Marfan syndrome? Select one: a. 50% b. 25% c. 100% d. 0% e. 75%
In humans, the genetic disease cystic fibrosis is caused by a recessive allele (a). The normal (healthy) allele is dominant (A). What is the genotype of someone who has cystic fibrosis? What are the two different genotypes that a healthy person could have? If two people were both heterozygous for the cystic fibrosis gene, what fraction of their children would be likely to have this disease? Hint: Draw a Punnett square to figure it out.
In Labrador retrievers, coat color is controlled by gene interaction in which homozygosity for a recessive allele can mask the phenotypic expression of a second gene. This genetic interaction is known as ________ and has a characteristic ________ ratio.
Hair texture is determined by gene c in an incomplete dominance inheritance pattern, where the heterozygous condition (c1c2) results in wavy hair. Hairline is controlled by gene H, where a widow's peak is dominant to a straight hairline. If a woman with curly hair and a straight hairline has a child with a man with a widow's peak and straight hair (his mom had a straight hairline), what is the chance they would have a kid that has exactly the same hair as mom? Draw the Punnett square and demonstrate the possible genotypes and phenotypes that could result from these two parents' mating.
As seen in the photo, Labradors come in three colors-- black, brown and yellow. What is the genetic basis for these different coat colors? One gene produces melanin, a pigment which is deposited in the dog's fur and makes the color dark. With this gene, allele B (black) is dominant to allele b. Only in the case of a recessive homozygote (bb) will the dog's phenotype be brown. The regulatory gene is separate from the melanin gene but it acts as a switch, either turning the melanin gene on or turning it off. Allele E is dominant and allows for the melanin to be deposited in the dog's fur ("on" switch), but if the switch gene is a recessive homozygote, the melanin is blocked ("off" switch) and a yellow dog is the result! Review the information on Labrador retrievers above. What are the phenotypic ratios of the F1 generation offspring of two dihybrids? Make sure to match the numbers with coat colors (e.g, which number in the ration goes with which color). Use a Punnett square to…
Piebald spotting is a condition found in humans in which there are patches of skin that lack pigmentation. The condition results from the inability of pigment-producing cells to migrate properly during development. Two adults with piebald spotting have one child who has this trait and a second child with normal skin pigmentation. a. Is the piebald spotting trait dominant or recessive? What information led you to this answer?
In mice, the wild-type coat color, agouti (AA) [left mouse], is dominant to solid-colored, black fur (aa) [middle mouse]. However, a separate gene (C) is necessary for pigment production. A mouse that is homozygous for a recessive c allele at this locus is unable to produce pigment and is albino [right mouse] regardless of the allele present at locus A. Thus, the following genotypes are listed with their associated phenotypes: ~ A/A; C/C or A/A; C/c or A/a; C/C or A/a; C/c ==> "agouti" ~ a/a; C/C or a/a; C/c ==> "black" ~ A/A; c/c or A/a; c/c or a/a; c/c or a/a; c/c ==> "albino" This is an example of recessive epistasis, in which the recessive c allele "stands upon" the possible genotypes for the A gene (A/A, A/a, or a/a). If two agouti mice with the A/a; C/c genotype are mated, what is the expected phenotypic ratio in their offspring? A.9 albino, 4 agouti, 3 black B. 9 agouti, 4 albino, 3 black C.9 black, 4 albino, 3 agouti D.9 agouti, 4 black, 3 albino
In rats, the following genotypes of two independently assorting autosomal genes determine coat color: A-B- (gray) A-bb (yellow) aaB- (black) aabb (cream) A third gene pair on a separate autosome determines whether or not any color will be produced. The CC and Cc genotypes allow color according to the expression of the A and B alleles. However, the cc genotype results in albino rats regardless of the A and B alleles present. Determine the F1 phenotypic ratio of the following crosses: (a) AAbbCC * aaBBcc (b) AaBBCC * AABbcc (c) AaBbCc * AaBbcc (d) AaBBCc * AaBBCc (e) AABbCc * AABbcc
In mice, the A allele causes agouti fur, the AY allele causes yellow fur and is dominant to the A allele. The homozygous AY AY genotype is lethal. Why is the AYAY homozygous condition lethal? The AY allele lacks an upstream merc gene which is required for normal embryonic development. The AY allele contains a null mutation in the A gene, which is required for normal embryonic development. The yellow pigment produced by A allele is required for survival. The AY allele highly transcribes the merc gene which is lethal in a homozygous AYAY individual. None of the other answers are correct.
In genetics, the dash symbol (–) is a “wild card” that stands for either the dominant allele or the recessive allele; for example, A– means the individual has either the genotype AA or Aa. Two genes that undergo independent assortment affect coat color in Duroc pigs. Each gene has two alleles, one of which is dominant for coat color. Genotypes of the form A– B– are red, those of the form A– bb and aa B– are sandy, and genotype aa bb is white. What ratio of red:sandy:white is expected from the cross Aa Bb x Aa Bb?