In guinea pigs, rough coat (R) is dominant over smooth coat...

In guinea pigs, rough coat (R) is dominant over smooth coat (r). For coat color, black coat (B) is dominant over white coat (b). A female guinea pig with a smooth, white coat is crossed with a male guinea pig who is heterozygous for both traits. STEP 1: What is the genotype of the two guinea pigs with respect to coat smoothness AND coat color? Female guinea pig Male guinea pig STEP 2: Draw a Punnett square below showing all the possible combinations of alleles for the offspring of this cross. STEP 3: Answer the following questions: What is the probability that the offspring will have a smooth, white coat? What is the probability that the offspring will have a black coat color?

Transcript

00:01 So you have a guinea pig, you have two different traits.

00:06 One is called roughness, smoothness, and then the other is color.

00:10 Rough is dominant to smooth and black dominant to white.

00:15 So you have two parent, female with smooth white and crossed with male with hatter leggers for both.

00:23 First of all, what is the genotype of the two guinea pig when it comes to the smoothness and color? the female has a phenotype of smooth and white.

00:39 So we know that both phenotypes are recessive when it comes to the trait.

00:44 So only when you have homo zeigers recessive, you will have recessive phenotype.

00:49 So this tells us that it must have homo zeigers lower r and homo zeigers lower b.

00:55 So this is a double recessive and homo zeigers.

00:58 And the male is hatter leggers for both traits.

01:01 Since hatter leggers show dominant, it will be a rough and black.

01:11 And hatter leggers means it's capital r, lower r, capital b and lower b.

01:17 The next step, the question asks you to draw a punnett square below, show all the possible combination of allele for the offspring for this cross.

01:24 So let's look at the female.

01:26 Female only has as a homo zeigers lower r and lower b.

01:31 So this means that it only produces one type of gametes, which is lower r and lower b.

01:37 So this means that it will produce four gametes.

01:41 They're all having the same genotype, lower r and lower b.

01:45 Now the male has hatter leggers genotype.

01:49 So it's a lot more complicated.

01:51 We assume r and b are assorted independently.

01:55 So you have different combinations.

01:58 For example, capital r was capital b, capital r assorted with lower b, lower r assorted with capital b or lower r with lower b.

02:14 So you can see that the male produced four possible gametes and the female only produced one type of gametes...

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