Labrador retrievers may be black, brown (chocolate), or golden (y...

Question

Labrador retrievers may be black, brown (chocolate), or golden (yellow) in color (see chapter-opening photo). While each color may breed true, many different outcomes are seen when numerous litters are examined from a variety of matings where the parents are not necessarily true breeding. Following are just some of the many possibilities.

(a) black x brown → all black
(b) black x brown → 1/2 black
1/2 brown
(c) black x brown → 3/4 black
1/4 golden
(d) black x golden → all black
(e) black x golden → 4/8 golden
3/8 black
1/8 brown
(f) black x golden → 2/4 golden
1/4 black
1/4 brown
(g) brown x brown → 3/4 brown
1/4 golden
(h) black x black → 9/16 black
4/16 golden
3/16 brown

Propose a mode of inheritance that is consistent with these data, and indicate the corresponding genotypes of the parents in each mating. Indicate as well the genotypes of dogs that breed true for each color.

Accepted Answer

Alright everyone, let's look at our next problem. It says pissed. Asus determines, determines the laboratory retrievers coat color. Big B denotes black pigment, Little B denotes brown pigment recessive and the expression of the B. Locus is controlled by the locus. Which of the following is inaccurate. Were given four answer choices that show different Jenna types and what color the coat color will be as a result. So we want to remember that we're gonna be looking for the inaccurate statement. Three of these will be correct and one our answer will be incorrect. So let's recall from our content video what episode Asus is little definitely up here when jeans at two different los I interact to influence the expression of a single trait. So in this case our single trait is coat color and we have the B gene, Bigby black, little B. Brown and the E. Jean. And what our definition says, what our question says here is that the expression of the B locus is controlled by the locus. So that means that we need at least one dominant E. A little for that B. Gene to be expressed. So what does that mean? In practicality? In terms of the phenotype resulting from different Jenna types? Well, it means that if we have a big be combined with any other alil and a big E. Combined with any other alil, we're going to end up with a black coat, we have the dominant biggie gene allowing the expression of the B gene and the dominant black Alil resulting in a black coat. In addition, if we have little B, Little B. And then B. G. With any other alil, we're going to see a brown coat. We have the big E. A little that's needed to allow the B. Gene to be expressed. And then we have a home as I guess recessive little B. Little B. Which results in a brown coat, the recessive trait and then finally any combination of B. Alleles with little E. Little E. Will result in a yellow coat. The recessive recessive. Little E. Little E. Means that that black brown trait that B. Gene cannot be expressed and you'll have a yellow coat. So with this in mind let's evaluate our answer choices, remembering that we're looking for the inaccurate statement. So in answer A. We have big B. Little B. Biggie Biggie gives black. Well here we have our dominant big B. Gene and we have at least one dominant allele. So this is true. So choice A cannot be our answer choice. B says little B. Little B. Biggie. Little E. Gives brown. Well we've got our biggie Aaliyah also R. B. Gene can be expressed and then we have little B. Little B. That recessive homos I guess um homem recessive be trait. So that does give a brown coat. So that's true and can't be our answer. Then in choice C. We have at least one big E. A little at least one big B. A little. So we can express that dominant black trait says that gives black that is true. So that can't be our answer. Finally, let's look our remaining choice D. And we see that it has little B. Little B. Biggie biggie. So we've got at least one dominant allele. We can express the B trait. And then for RB gene we are homos, I guess recessive little B. Little B. So that would give not yellow but brown. Yellow just occurs when you have two recessive genes not allowing the expression of that gene. So this is not correct and therefore this is our answer. So which of the following is inaccurate choice. D. Little B. Little B. Biggie biggie gives. Yellow is an inaccurate statement. See you in the next video.

Key Concepts

Mendelian Inheritance

Genotype and Phenotype

Punnett Squares

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