Concept explainers
a.
To determine: The expected proportions of
Introduction: The hair color in humans is regulated by two interacting genes. The pigment melanin is present in both types of hair that is brown hair as well as blond hair; however it is present more in brown haired people. Blond hair (b) is recessive to brown hair (B). The synthesis of melanin is coded by another gene having two alleles. The (M) allele allows the synthesis of melanin whereas the (m) allele prevents it. The genotypes (mm) are albino. The pigment melanin is present in both types of hair that is brown hair as well as blond hair; however it is present more in brown haired people. Blond hair (b) is recessive to brown hair (B).
b.
To determine: The expected proportions of phenotypes in children of BbMm ×BbMm.
Introduction: The mating has taken place between two doubly heterozygous individuals. Both of them have a genotype of BbMm that is both will have brown hair gene as well as gene for melanin synthesis.
c.
To determine: The expected proportions of phenotypes in children of BbMm and bbmm.
Introduction: One of the parents have a genotype of BbMm that is will have brown hair gene as well as gene for melanin synthesis and the other parent is albino.
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Biology
- In wheat, aleurone cells form a thin layer of the seed coat that is critical to early gene expression in plant development. The color of this layer of cells is controlled by two alleles of a gene [colored aleurone (R) is dominant to colorless (r)]. A second gene is known to control the color of leaf tips [green leaf tip (G) is dominant to yellow (g)]. Two plants, each heterozygous for both characteristics, are test crossed to homozygous recessives, and their progeny are combined to produce the following totals: colored green 102 colored yellow 98 colorless green 103 colorless yellow 97 a) Use chi-square analysis to test these data for an independent assortment of the two characteristics (table provided). Please show work, how your expected values are calculated, and explain what your results indicate about the data. b) You decide to be cautious in your analysis, and decide to analyze the progeny from each of the crosses individually (instead of adding them together as shown above).…arrow_forwardAlbinism occurs when cells cannot chemically synthesize pigment molecules. This occurs because the genes encoding the proteins that catalyze those synthesis reactions have sustained mutations. Based on this description, briefly explain whether you think mutations that cause albinism would be more likely to be dominant or recessive.arrow_forwardPigments in some bears are the result of epistasis between 2 genes. The black coat color is only produced when both wildtype forms of genes D and E are present. When gene D (D-ee) is wildtype alone, offspring are white. When gene E (ddE-) is wildtype alone, offspring are brown. When no wildtype alleles are present (ddee) offspring are all white. Based on this describe the relationship between the genes D and E. Group of answer choices A-D is dominant to E B- E is dominant to D C- D is epistatic to E D- E is epistatic to Darrow_forward
- Genes A, B, C, D, and E are independently assorting. The dominant alleles A, B, C and D encode enzymes that catalyse the corresponding reactions indicated above. The recessive alleles a, b, c and d are non-functional and do not produce active enzymes. The dominant E allele totally inhibits the action of gene C, while the recessive allele e has no effect. a) Determine the F1 and F2 phenotypes from a cross between AAbbCCDDEE and AABBCCDDee plants. b) What proportion of the offspring of an AaBBCCDdEe x AaBBCcDdEe cross is expected to have coloured flowers?arrow_forwardIn 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 Balleles present. Determine the F1 phenotypic ratio of the following crosses: (a) AAbbCC x aaBBcc; (b) AAbbCC x aaBBcc; (c) AABBCC x AABbcc.arrow_forwardConsider the following three autosomal recessive mutations in Drosophila:vestigial wings (v); wild type is long (v+)black body color (b); wildtype is gray (b+)plum eyes (p); wildtype is red (p+)A vestigal, gray, red female (homozygous for all three genes) is crossed with a long wing, black, plum male (homozygous for all three genes). The F1 female progeny are mated with triple homozygous recessive males. Here is the phenotypic data for the F2 progeny:vestigal; gray; red 580long wings; black; plum 592vestigal; black; red 45long; gray; plum 40vestigal; black; plum 89long; gray; red 94vestigal; gray; plum 3long; black; red 5A total of 1448 progeny were counted.Which one of the following values is the approximate distance between the plum eye color and black body color loci?arrow_forward
- Albinism in animals is caused by recessive mutations inone of several autosomal genes required for synthesis ofmelanin, a chemical precursor for many skin and eye pigments. Albino animals are often confused with so-calledleucistic animals that are white due to recessive mutationsin a gene required in a different pathway, for example apathway for development of the cells that produce all skinpigments. Suppose you have two white hummingbirds—a male and female—and they have mated. Assuming thatall relevant mutations are rare, autosomal, and recessiveto wild-type alleles, what would you expect their progenyto look like under the following conditions:a. They are both albinos.b. They are both leucistic.c. One is albino and the other is leucistic.arrow_forwardCertainly, not all Muppets look like the one shown in the picture below, nor do they all look the same. In fact, there’s a great deal of phenotypic variation in Muppets. Two traits that have been particularly well-studied are curly hair presences and skin color. One individual is a male, and he possesses a green skin and no hair, whereas the female individual possess a curly hair and pink skin. Let’s call the gene controlling skin coloration S and that controlling hair H. In this species, both hair and green skin are recessive traits. Both of the individuals shown are homozygous. 1. What is the genotypes of Miss Piggy: 2. Kermit's Genotype: 3. If these two lovebirds (er, love-muppets?) mated, what would their offspring look like? Describe all phenotype combinations possible and the ratios in which they would occur?arrow_forwardOne of the X chromosomes in a particular Drosophila female had a normal order of genes but carried recessive alleles of the genes for yellow body color (y), vermilion eye color (v), and forked bristles (f), as well as the dominant X-linked Bar eye mutation (B). Her other X chromosome carried the wild-type alleles of all four genes, but the region including y+, v+, and f+ (but not B+) was inverted with respect to the normal order of genes. This female was crossed to a wild-type male in the cross diagrammed her. The cross produced the following male offspring: Y v f B 48 y+ v+ f+ B+ 45 y v f B+ 11 y+ v+ f+ B 8 y v f B 1 y+ v+ f+ B+ 1 a. Why are there no male offspring with the allele combinations y v f+, v+ v+ f, y v+ f+, or y+ v f (regardless of the allele of the Bar eye gene)? b.What kinds of crossovers produced the y v f b+ and v+ y+ f+ B offspring? Can you determine any genetic distances from these classed of progeny? c. What kinds of crossovers produced the…arrow_forward
- One of the X chromosomes in a particular Drosophila female had a normal order of genes but carried recessive alleles of the genes for yellow body color (y), vermilion eye color (v), and forked bristles (f), as well as the dominant X-linked Bar eye mutation (B). Her other X chromosome carried the wild-type alleles of all four genes, but the region including y+, v+, and f+ (but not B+) was inverted with respect to the normal order of genes. This female was crossed to a wild- type male in the cross diagrammed her. The cross produced the following male offspring:* table in figure a. Why are there no male offspring with the allele combinations y v f+, v+ v+ f, y v+ f+, or y+ v f (regardless of the allele of the Bar eye gene)?b. What kinds of crossovers produced the y v f b+ and v+ y+ f+ B offspring? Can you determine any genetic distances from these classed of progeny?c. What kinds of crossovers produced the y+ v f+ B+ and y v+ f B offspring?arrow_forwardIt is assumed that in Drosophila the following genotypes produce phenotypes. َA- B- = Red color A- bb = Plum color aa B- = Magenta color aa bb = White color The third latent genotype, cc, kills homozygous Plums, but has no effect on other genotypes. Also, genotype C- does not produce a large phenotype. If first-generation Drosophilas are heterozygous for all of these genes and interbreed, what phenotypic ratios are expected in society?arrow_forwardMatch Genotype With Phenotype Consider a newly discovered organism that is bioluminescent. Scientists studying this animal have discovered that there are two enzymes necessary for the animal to glow, encoded by the bright and red genes. Furthermore, scientists have confirmed that for bioluminescence to be displayed, an individual must have at least one copy of the dominant allele for each gene, (B and R). Match the genotypes with their correct phenotypes, glowing or nonglowing. BBRR Bbrr bbrr Glowing BbRR bbRR BbRr bbRr Non-glowing BBRr BBrr Carrow_forward
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