Gene B located on X chromosome in quinea pigs determine either black (B allele)

Question

Gene B located on X chromosome in quinea pigs determine either black (B allele) or orange (b allele) color. Heterozygous quinea pigs are tortoise-shell. Explain if both males and females can be tortoise-shell. What would be all possible genotypes for guinea pigs if they are also heterozygous for gene S that determines the presence of spots (S allele) or absence of spots (s allele)?

im pretty sure the answer to the first question is only females b/c males only have one x chromosome and therefore are not able to be heterozygous for gene B, but not so sure about the 2nd question

I believe S is assumed in this case to be located on an allosome

Explanation / Answer

The answer for first question is only females can be tortoise shell. For males, there is only one 'X' chromosome and the possible genotypes will be XB Y and Xb Y which will be black and orange respectively. For females, there are three possibilities XBXB (Black), XBXb (Tortoise shell) and XbXb (orange).

Assuming that 'S' also locates in 'X' chromosome, then in question they are asking for the all the genotypes possible.

Genotypes for male: XS Y and Xs Y

Genotypes for female: XSXS, XSXs and XsXs

Related Questions

Navigate

• Browse (All)
• Browse G
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.