Cross 2 heterozygous running, heterozygous black mice

A cross between a mouse that is waltzing brown with a mouse that is running brown generates some offspring that waltz. What are the parental genotypes? What Is the offspring phenotype ratio

A cross between a mouse that is running with black fur and a moue that is waltzing brown generates some offspring that are running, with black fur and some that are waltzing, with black. What are the parental genotypes? What is the offspring phenotypic ratio?

The parental genotypes would be:

Running black mouse: BbRr

Waltzing brown mouse: bbrr

The offspring phenotypic ratio would be 1:1, with half of the offspring being running black (BbRr) and the other half being waltzing black (bbRr).

To determine the parental genotypes and offspring phenotypic ratios, we can use Punnett squares.

1. First cross: Two heterozygous running, heterozygous black mice.

Parental genotypes:
Male mouse: RrBb (heterozygous running, heterozygous black)
Female mouse: RrBb (heterozygous running, heterozygous black)

Punnett square:

R r
--------------------
B | RB | RB |
B | RB | RB |
--------------------
B | rb | rb |
B | rb | rb |
--------------------

From the Punnett square, we can see that the possible genotypes of the offspring are RRBB, RRbB, RRBb, RRbb, RrBB, RrBb, RrbB, Rrbb, rRBB, rRbB, rRBb, rRbb, rrBB, rrBb, rrbb.

Offspring phenotypic ratio:
- Running, black fur mice (RRBB, RRBb, RrBB, RrBb): 4/16 or 1/4
- Running, brown fur mice (RRbb, Rrbb): 2/16 or 1/8
- Waltzing, black fur mice (rrBB, rrBb): 2/16 or 1/8
- Waltzing, brown fur mice (rrbb): 2/16 or 1/8

2. Second cross: A mouse that is running with black fur and a mouse that is waltzing brown.

Parental genotypes:
Male mouse: RrBb (running, black fur)
Female mouse: rrBb (waltzing, brown fur)

Punnett square:

R r
--------------------
B | RB | RB |
b | Rb | Rb |
--------------------
B | rB | rB |
b | rb | rb |
--------------------

From the Punnett square, we can see that the possible genotypes of the offspring are:
- Running, black fur mice (RB, rB): 2/4 or 1/2
- Waltzing, black fur mice (Rb, rb): 2/4 or 1/2

Offspring phenotypic ratio:
- Running, black fur mice: 2/4 or 1/2
- Waltzing, black fur mice: 2/4 or 1/2

I hope this helps! Let me know if you have any further questions.

To determine the parental genotypes and the offspring phenotypic ratio, we need to understand the basic principles of genetics. Specifically, we need to know how genes are inherited and expressed.

In mice, the trait for running or waltzing (locomotion) and the trait for black or brown fur color are determined by different genes. We can represent these genes using letters, such as R for running and W for waltzing, and B for black fur color and b for brown fur color.

Now let's analyze each scenario separately:

1. Cross between heterozygous running (Rr) and heterozygous black (Bb) mice:
Since the traits for running and fur color are controlled by different genes, we can separate them and analyze them individually:

Running trait:
The cross between two heterozygous running mice (Rr x Rr) will produce offspring with three possible genotypes: RR, Rr, and rr. The genotype RR represents mice that are homozygous for the running trait (purebred for running), Rr represents mice that are heterozygous for the running trait (carrying both running and non-running alleles), and rr represents mice that are homozygous for the non-running trait (purebred for non-running).

Fur color trait:
Similarly, the cross between two heterozygous black mice (Bb x Bb) will produce offspring with three possible genotypes: BB, Bb, and bb. The genotype BB represents mice that are homozygous for black fur color (purebred for black), Bb represents mice that are heterozygous for the fur color trait (carrying both black and brown alleles), and bb represents mice that are homozygous for brown fur color (purebred for brown).

To determine the parental genotypes, we combine the corresponding genotypes for each trait. Therefore, the parental genotypes for this cross are RrBb.

For the offspring phenotypic ratio, we need to consider the inheritance of both traits simultaneously. To do that, we multiply the probabilities of each trait separately:

- For running: The possible genotypes that can produce mice with a running phenotype are RR and Rr (since rr represents the non-running trait). Therefore, the probability of offspring with a running phenotype is 2/3.

- For black fur color: The possible genotypes that can produce mice with black fur color are BB and Bb (since bb represents the brown fur color trait). Therefore, the probability of offspring with black fur color is 2/3.

By multiplying these probabilities (2/3 x 2/3), we find that approximately 4/9 (or 44%) of the offspring will have both the running trait and black fur color. The remaining 5/9 (or 56%) will have either the running trait or black fur color, or neither.

2. Cross between running with black fur (RrBb) and waltzing brown (rrbb) mice:
Similar to the previous scenario, we need to analyze the inheritance of the running trait and fur color trait separately:

Running trait:
The cross between a running mouse with black fur (RrBb) and a waltzing brown mouse (rrbb) will produce offspring with three possible genotypes for the running trait: RR, Rr, and rr. The genotype RR represents mice that are homozygous for the running trait, Rr represents mice that are heterozygous for the running trait, and rr represents mice that are homozygous for the non-running trait.

Fur color trait:
The cross between a running mouse with black fur (RrBb) and a waltzing brown mouse (rrbb) will produce offspring with three possible genotypes for the fur color trait: BB, Bb, and bb. The genotype BB represents mice that are homozygous for black fur color, Bb represents mice that are heterozygous for the fur color trait, and bb represents mice that are homozygous for brown fur color.

Therefore, the parental genotypes for this cross are RrBb (running with black fur) and rrbb (waltzing brown).

For the offspring phenotypic ratio, we again multiply the probabilities of each trait separately:

- For running: The possible genotypes that can produce offspring with a running phenotype are RR and Rr. Therefore, the probability of offspring with a running phenotype is 2/3.

- For black fur color: The possible genotypes that can produce offspring with black fur color are BB and Bb. Therefore, the probability of offspring with black fur color is 2/3.

By multiplying these probabilities (2/3 x 2/3), we find that approximately 4/9 (or 44%) of the offspring will have both the running trait and black fur color. Additionally, 2/9 (or 22%) of the offspring will have the running trait but brown fur color, 2/9 (or 22%) will have waltzing behavior but black fur color, and 1/9 (or 11%) will have waltzing behavior with brown fur color.

In summary, the phenotypic ratio of the offspring from this cross is approximately 4:2:2:1, representing 4 mice with both running and black fur, 2 mice with running but brown fur, 2 mice with waltzing behavior but black fur, and 1 mouse with waltzing behavior and brown fur.