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I think I have the correct answer, but I'd like to double check it before I submit.. here's the q..

In a family of 4 dogs, the father dog has black sports, the mother dog has no spots, and one of the puppies is spotted black, while the other isn't.

what are the genotypes of each dog? There's only 1 possible genotype for each dog, so the answer includes a single genotype for each dog.

2007-02-28 12:42:14 · 5 answers · asked by Emo B 5 in Science & Mathematics Biology

5 answers

In this oversimplistic explanation of how dog spots are passed from generation to generation, let's first assume that "S" is the gene for Spots, and "s" for no spots. Let's also assume that "S" exerts a dominant Phenotype over "s".

Since the mother has a phenotype of no spots, her genotype must be ss.
Since one of the puppies has no spots (ss), and it had to get one of the "s" from the father, that must mean that the father, who has spots (and therefore has at least one copy of S, must be "Ss".
As for the other pup, it must have a "s" from mom, because mom only has s's, and it must have it's "S" from dad, because it has spots and that's the only place the "S" could have come from.

Hope that helps.

2007-02-28 12:46:34 · answer #1 · answered by BP 7 · 0 1

user-friendly words? ok then: Phenotype- exterior visual charm (i.e. Blue Eyes) Genotype- Homozygous Dominant/Recessive (RR/rr), Heterozygous (Rr) that has effects on the phenotype. Gamete- A mature intercourse cellular that has a single set of chromosomes (unpaired).

2016-09-30 01:04:47 · answer #2 · answered by ? 4 · 0 0

Your explanation tells me that spots are dominant (S) and no spots are recessive (s), so depending on the number of spotted dogs vs. no spotted dogs some will be heterozygote and others homozygote, but you really need more information about the mothger and father dgs (were they homozygote or heterozygote),because that really determines if the puppies will also be homozygote or heterozygote. You also need that information to determine phenotypic and genotypic ratios.

2007-02-28 14:11:40 · answer #3 · answered by drjefferson2010 1 · 0 1

To give a correct conclusion to you Question, you will have to state the number of puppies.
If there were 4 puppies, then the genotype of the puppies will be:
Bb, bb, bb and bb.
the phenotype will be one hetrozygous spotted puppy and three homozygous plain puppies.

2007-02-28 12:49:31 · answer #4 · answered by Aditi 2 · 0 3

If spots are dominant, then S = spotted, s = no spots.

Parents: spotted x no spots (Ss x ss)
Puppies: spotted and not spotted (Ss and ss)

The parent with spots must be heterozygous, Ss, because there is a puppy that is ss (each parent had to have s) and the parent itself was spotted (had to have S).

The parent without spots had to be ss if that condition is recessive.

Then the puppies can only be Ss and ss.

2007-02-28 12:48:29 · answer #5 · answered by ecolink 7 · 0 1

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