(3) You are interested in understanding the genetics ofcoat color and hair lengt
ID: 209814 • Letter: #
Question
(3) You are interested in understanding the genetics ofcoat color and hair length in dachshunds, which have one of 2 primary colors (brown and black) and either long or short hair. You cross a pure-bred black long-hair dachshund with a brown short-hair dachshund, and all of the offspring are black with short hair. When you intercross these offspring, you obtain the following phenotypic ratios: 44 black short hair dachshunds 23 black long hair dachshunds 21 brown short hair dachshunds (a) Perform a statistical test to determine if these data support a hypothesis of Mendelian inheritance based on independent assortment. (4 points) (b) If you reject the null hypothesis of Mendelian inheritance, propose an alternative hypothesis. How specific can you be in your hypothesis? Explain the limits to the conclusions you can make given these data alone. points) (c) Upon doing research, you learn that a locus controlling coat color and a locus controlling hair length are linked with a map distance of 8 cM. Predict the phenotypic ratios that will result from a testcross of the Fl generation (produced above). (3 points) (d) Given these data, predict the phenotypic ratios expected from an intercross of the Fl generation (from above). (4 points) (e) Perform a statistical test to determine if the data provided earlier (44 black & short; 23 black & long; 21 brown & short) support this hypothesis based on linkage. (4 points)Explanation / Answer
Based on the Law of Independent Assortment, the Mendelian table could prove the statement.
The F1 generation of the traits :
Bb x Ll would give BL bL Bl bl as their offsprings.
The phenotypic ratio of F1 generation is 3:1.
These offsprings could be taken into the punnets square for confirming the phenotypic ratio which could prove the law to be correct.
F2 generation:
Thus number of Black dogs with long hair are 9
Number of Black dogs with short hair are 3
Number of Brown dogs with Long hair are 3
Number of Brown dogs with short hair is 1.
Thus this fulfills the phenotypic ratio of 9:3:3:1. The allele pairs separate independently during the formation of gametes.
BL Bl bL bl BL BLBL BLBl BLbL BLbl Bl BlBL BlBl BlbL Blbl bL bLBL bLBl bLbL bLbl bl blBL blBl blbL blblRelated Questions
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