In guinea pigs, gene B is for black, b is for white the heterozygote is a mixture, called agouti. ( sex linked and non dominant) , a litter consists of 5 agouti females and 6 black males , if the parents of this litter had more offspring , what other phenotypes would you expect to appear, and list possible genotypes and phenotypes and their ratio
It would help if you proofread your questions before you posted them. What is "sex linked and non dominant"?
To determine the possible genotypes and phenotypes that could appear in the offspring, we need to analyze the genotypes of the parents. From the given information, we know that gene B is for black (dominant) and gene b is for white (recessive). The heterozygote (Bb) results in a mixture called agouti, which is non-dominant. We also know that the given litter consists of 5 agouti females and 6 black males.
Let's assume the genotype of the female parent (dam) is Bb, as the dam can produce both agouti and black offspring. We don't know the genotype of the male parent (sire), so we need to consider all possibilities.
Possible Male Genotypes:
1. BB: If the sire is homozygous dominant for black (BB), all the male offspring will be black (Bb).
2. Bb: If the sire is heterozygous (Bb), half of the male offspring will be black (Bb), and half will be agouti (bb).
3. bb: If the sire is homozygous recessive for white (bb), all the male offspring will be agouti (bb).
Possible Female Genotypes:
Since all the females in the litter are agouti, we can conclude that the female parent (dam) must have the genotype bb.
Now, let's list the possible genotypes and phenotypes of the offspring:
1. If the sire is BB and the dam is bb:
- Female offspring: All agouti (bb)
- Male offspring: All black (Bb)
2. If the sire is Bb and the dam is bb:
- Female offspring: Half agouti (bb), half black (Bb)
- Male offspring: Half agouti (bb), half black (Bb)
3. If the sire is bb and the dam is bb:
- Female offspring: All agouti (bb)
- Male offspring: All agouti (bb)
Finally, let's determine the ratios of the different phenotypes in each case:
1. BB sire and bb dam:
- Female offspring: 0 agouti (0%), 5 black (100%)
- Male offspring: 0 agouti (0%), 6 black (100%)
2. Bb sire and bb dam:
- Female offspring: 2 agouti (40%), 3 black (60%)
- Male offspring: 3 agouti (50%), 3 black (50%)
3. bb sire and bb dam:
- Female offspring: 7 agouti (100%), 0 black (0%)
- Male offspring: 6 agouti (100%), 0 black (0%)
Note: These ratios are approximate and may vary in actual genetic crosses due to chance.
Therefore, based on the given information and possible parental genotypes, the expected phenotypes and their ratios in the offspring are as listed above.