oo Simple Mobile 4G 9:36 PM 60% roosevelt.blackboard.com 5. Among the native Ame

Question

oo Simple Mobile 4G 9:36 PM 60% roosevelt.blackboard.com 5. Among the native Americans, two types of earwax are seen, dry and sticky. A geneticist studied the inheritance of this trait by observing the types of offspring produced by different kinds of matings. He observed the following numbers: (2.0pts.) Parents number of mating pairs Sticky Dry Sticky x Sticky 10 21 0 42 a) How is earwax type inherited? b) Why are there no 3:1 or 1:1 ratios in the data shown in the chart? 6. Yellow body color in Drosophila is determined by the recessive allele y of an X-linked gene, and the wild-type gray body color is determined by the y+ allele. What genotypic and phenotypic ratios would be expected from the following crosses (4.0 pts.): (a) Yellow female X wildtype male b) Yellow male X wildtype (homozygous) female (c) Daughter from mating in part b X wildtype male (d) Daughter from mating in part b X yellow male 7. Consider the following cross: Bb Hh TT Ee Rr GG x BB HH Tt Ee Rr gg. How many genotypes are possible for their offspring (1.0 pts)? 8. Working on a genetics experiment with Drosophila, you count the F2 generation of the dihybrid cross between a female fly who has a black body and normal wings and a male who is wildtype for body color but is apterous (no wings). An F1 female is then crossed to a true breeding male who has a black body and is wingless. You obtain the following count for the F2 generation (1.0 pts): 90 wildtype (tan body, winged) 733 black body, wildtype wings 717 wildtype body, apterous 80 black body, apterous Calculate the recombination frequency between body color and wing traits.

Explanation / Answer

5.a. Earwax is controlled by one gene with two alleles. However this trait is inherited simply as other mendalian trait. Sticky appears to be dominant and Dry is recessive. If so, crosses between "Dry" individuals should produce only dry offspring while crosses between sticky and dry and sticky and sticky would be expected to give rise to both types.

b. Because this is not a true breeding.Sticky and dry individuals are not known.

6.a.YY X yy where Y is dominant gene for gray colour and y for yellow recessive.

we wil get 1:1 ratio.

b. yyX YY

since trait is X linked therefore all boys will be yellow and all girls will be carrier of yellow but grey bratio will be 1:1

c. yY YY

there will be one affected male child, one carrier daughter and 1 unaffected son and 1 unaffected daughter..

ratio will be 1:2:1

d. yY X yy

two affected male and one carrier female one unaffected daughter.

1:1

7. possible genotype = (2)n

=(2)11

=2048

8. Tan body winged 90

black body wing type 733

apterus body 717

black body apterus 80

recombinant type 80+90 =170

Total offsprings= 1620

distance between two gene = 170/1620 X 100 =10

= 10 CM

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