In addition to C.elegans and Drosophila, Zebrafish are also anothermodel organism - and have a spine. We're interested in twophenotypes, a curved spine and a gene that causes skin tumors toform on the fish's skin. We'd like to know if we could use thecurved spine as an indicator if a fish may develop tumors (if thegenes are linked). We'll assume that each of these traits iscontrolled by a single gene where:
a curved spine is the result of a dominant allele S (and a normalspine is the result of recessive alleles s),
and tumor growth is the result of a recessive allele t (and notumor growths are a dominant T allele).
A testcross isperformed with a fish that is heterozygous for both genes and theresulting progeny are given below.
TtSs xttss
curved spine &tumors 18
curved spine & no tumors 23
normal spine & tumors 26
normal spine & no tumors 15
1. Assumefor a moment that these genes are linked. If so, what allelecombinations are parental in the TtSs genotype listed in thecross?
Are these twogenes following Mendelian inheritance patterns? UseChi-Squared analysis to test them. (X2 = the sum of(o-e)2/e)
2.X2 value : 3. Degreesof Freedom : 4. p-value: 5.Determination : NO they appear to beunlinked, or YES they may be linked Are these twogenes linked? Use Chi-Squared analysis to test them.(X2 = the sum of (o-e)2/e) 6.X2 value : 7. Degreesof Freedom : 8. p-value: 9.Determination : NO they appear to beunlinked, or YES they may be linked |
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