10. Fur colour in mice is an example of the effects of interaction between different genes. Wild type mice have agouti fur where the individual hairs are black with a yellow band producing the typical grey-like colour of agouti fur. Two different independently segregating genes are involved in the expression of coat colour: • A single gene with two alleles, A and a, determines the colour of the coat; Agouti (AA or Aa) is dominant over black (aa). • A different gene is required for the hair pigment to be synthesised and therefore expressed. When the dominant allele of this gene is present (C), pigment is produced and the agouti and black phenotypes can be expressed. A null allele (c, which produces an inactive form of the enzyme for pigment production) is recessive; when in the homozygous form (cc), no pigment is produced and the mice are albino. a) Write down the colour of the coat of mice with the following genotypes: Genotype Phenotype aaCc b) Consider the following cross: Parents Black x Albino Gametes F1 generation AaCC aaCC aC AaCc X X Aacc AAcc Ac All agouti Use a Punnet square to determine the genotypes and then the phenotypic ratio expected in the F2 generation when the F₁ agouti mice are interbred.

10. Fur colour in mice is an example of the effects of interaction between different genes. Wild type mice have agouti fur where the individual hairs are black with a yellow band producing the typical grey-like colour of agouti fur. Two different independently segregating genes are involved in the expression of coat colour: • A single gene with two alleles, A and a, determines the colour of the coat; Agouti (AA or Aa) is dominant over black (aa). • A different gene is required for the hair pigment to be synthesised and therefore expressed. When the dominant allele of this gene is present (C), pigment is produced and the agouti and black phenotypes can be expressed. A null allele (c, which produces an inactive form of the enzyme for pigment production) is recessive; when in the homozygous form (cc), no pigment is produced and the mice are albino. a) Write down the colour of the coat of mice with the following genotypes: Genotype Phenotype aaCc b) Consider the following cross: Parents Black x Albino Gametes F1 generation AaCC aaCC aC AaCc X X Aacc AAcc Ac All agouti Use a Punnet square to determine the genotypes and then the phenotypic ratio expected in the F2 generation when the F₁ agouti mice are interbred.

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter12: Mendel, Genes, And Inheritance

Section: Chapter Questions

Problem 9TYK: The ability of humans to taste the bitter chemical phenylthiocarbamide (PTC) is a genetic trait....

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Coat color of dogs depend upon the action of at least two genes. At one locus a dominant epistatic inhibitor of coat color pigment (I_) prevents the expression of color alleles at another independently assorting locus, producing white coat color. When the recessive condition exists in the inhibitor locus (ii), the alleles of the hypostatic locus may be expressed, iiB_ producing black and iibb producing brown. When dihybrid white dogs are mated together, determine the: (a) the type of gene interaction (b) the phenotypic proportions expected in the progeny (c) the chance of choosing, from among the white progeny, a genotype that is homozygous at both loci
1. In Drosophila melanogaster (fruit fly) experiment, if we are going to cross male and female red-eyed fruit flies, we have the resulting offspring ratio of 50% red-eyed for female, 25 % for red-eyed male and 25% for white-eyed male. Females which are either homozygous or heterozygous for a trait still expressed eye redness whereas males can easily be affected. Why is this so? a. Females are the carriers of a gene for eye redness b. Y chromosome is responsible for red eyes in fruit flies, c. The gene for eye redness is an X-link dominant trait, d. Having a red-eyed trait is dominantly expressed by females
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