Biology 3594A : Mutation Research Notes

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tanhippopotamus305

22 Dec 2011

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An hqx mouse, with only one copy of the bad gene, ends up losing half of it"s hair. Has retinal degeneration, then cerebellar degeneration, then rod and cone loss and function. At the age of a teenager it looks like a really old mouse: genotype. What is the hq mutation: harlequin mice carry an x-linked recessive mutation in the pdcd8 (programmed cell death 8) gene, which encodes a protein known as apoptosis-inducing factor (aif). In normal conditions, this is located in the inner and outer mitochondrial membranes but induces apoptosis when fragmented to the nucleus: aif deficiency leads to increased oxidative stess by ros and decreased atp production. Compare and contrast: plap and cii (mutant detection assays) Define and distinguish: mutant frequency - measures mutation burden at the phenotypic level, mutation pattern - mutation frequencies specific to the age or tissues of the organism.

Related Questions

9.3a. Define mutation and explain the two types of mutations in multicellular organisms and their phenotypic effects.

9.3b. Define a point mutation and how it may or may not result in a new phenotype.

9.3c. Describe chromosomal mutations, including deletions, duplications, inversions, and translocations.

9.3d. Define and distinguish spontaneous and induced mutations.

9.3e. Define âhotspotâ mutation and provide two examples.

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You are given 4 true-breeding mutant strains of fruit flies, each with a different eye colour
phenotype (apricot, orange, brown & scarlet). Specific reciprocal crosses between the recessive
mutant strains produced the following results in the F1 generations:
P1: apricot female x orange male F1 : apricot males and orange females
P1: orange female x apricot male F1 : orange males and females
P1: brown female x scarlet male F1 : wildtype males and females
P1: scarlet female x brown male F1 : wildtype males and females

i) Are the four mutant phenotypes all controlled by different alleles of a single gene? Explain.

ii) Which of the mutant phenotypes, if any, are due to allelic mutations?

iii) Which of the mutant phenotypes, if any, are due to alleles of autosomal genes? Explain.

iv) Using your own symbols for the mutations, indicate the genotypes of the F1 generation males
and females in each of the crosses.

v) Which of the F1 generations when intercrossed are likely to yield recombinant phenotypes in
the F2 generations? Explain showing the expected phenotypes and their proportions. (You
may assume that Mendelâs 2nd Law of Heredity holds true for the mutations involved in this
situation. Further assume that the double mutant results in a white eye color).

vi) Predict the outcome in the F1 generations of a reciprocal cross between a truebreeding strain
with brown eyes and another with apricot eyes.

Sometimes one gene may have the effect of suppressing an abnormal (mutant) allele of another gene, resulting in the normal phenotype. Flies that are homozygous for the mutant gene, suppressor or hairy wing (s/s) will have a normal phenotype if they are also homozygous for the mutant gene, hairy wing (h/h). The following questions refer to the offspring ratios after the mating of individuals heterozygous for the wild type and mutant alleles of BOTH suppressor of hairy wing (s⁺/s) and hairy wing (h⁺/h) genes. The genes, s⁺ and h⁺ are located on separate chromosomes. Use the symbols s^D, s^R, h^D, and h^R to denote the genotype of a fly that is heterozygous for:

A. Dominant (D) mutations in both s⁺ and h⁺

B. Recessive (R) mutations in both s⁺ and h⁺

i. What phenotypic ratio of offspring would you expect if suppression occurs when you sib-mate flies heterozygous for dominant mutations in both s⁺ and h⁺ ?

ii. What phenotypic ratio of offspring would you expect if suppression occurs when you sib-mate flies heterozygous for recessive mutations in both s⁺ and h⁺ ?

iii. Draw the punnett squares showing both the genotype and corresponding phenotype for EACH of the 16 outcomes for both scenarios.

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Biology 3594A : Mutation Research Notes

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