4. In mink (Mustela vison), as in most other mammals, many...

4. In mink (Mustela vison), as in most other mammals, many genes affect the color of the coat. These are of particular interest to breeders since new and different furs command premium prices. At least 13 genes are known to determine coat color in mink. The results of crossing wild-type with platinum (blue-grey) and aleutian are shown in the table below. Parents | F1 | F2 | Genotype of parent 1 | Genotype of parent 2 Wild-type X platinum | Wild-type | 3 wild-type: 1 platinum | | Wild-type X Aleutian | Wild-type | 3 wild-type: 1 aleutian | | Platinum X Aleutian | Wild-type | 133 wild-type: 41 platinum; 46 aleutian; 17 sapphire | | - Are these phenotypes due to one gene with multiple alleles or 2 genes that affect the same phenotype? Explain your logic. Fill in the parental genotypes in the table above. If you show your work, make it clear which cross it goes with. - What results would you expect if the wild-types from the cross between the platinum and aleutian were crossed with the sapphires? Show your work and give the genotypic and phenotypic ratios.

Transcript

00:03 In mink, as most other mammals, most genes affect the color of the coat.

00:09 There are particular interest to breeders since new and different fur command premium prices.

00:15 You have 13 genes known to determine coat color in mink.

00:19 Now you have three different crosses shown on the table.

00:22 So wild type crossed with platinum.

00:25 F1 shows wild type.

00:26 F2 shows 3 to 1 wild type and platinum.

00:30 Wild type crossed with elution apparent f1 wild type.

00:35 Now f2 is again 3 to 1 ratio.

00:39 The platinum crossed with elution f1 show wild type and f2 show 133 wild type, 41 platinum, 46 elution, and 17 sapphire.

00:51 Now these gene phenotype due to one gene or multiple with multiple alleles or two genes that affect the same phenotype explain logic and fill in the parental genotype in a table below.

01:04 If you look at the third cross platinum and elution, while wild type f1 but 9 to 3 to 3 to 1 ratio for the f2, we decide that most likely platinum and elution are two different genes.

01:48 So you can see 133, 41, 46, and 17 is roughly 9 to 3 to 3 to 1 ratio.

02:01 So this is a very classic dihybrid cross where two genes are involved.

02:15 So let's give each of these gene a name.

02:18 Let's say p platinum.

02:21 Let's call it gene p and elution gene a.

02:27 So let's go ahead and look at each of the cross.

02:33 So this is p, this is a.

02:39 Now, so for wild type, it obviously is wild type dominant for every single gene.

02:45 So for the number one cross, wild type cross with platinum.

02:57 As we just mentioned that platinum, we use gene p as a key.

03:02 So wild type is going to have, let's say, homozygous, capital p, and platinum is a recessive gene.

03:12 Let's call it homozygous lower p.

03:17 So that goes into the first two box of the table, genotype of parent number one and genotype of pair number two, number one and number two.

03:30 So now for this cross, as you can see that all f1 is going to have one allele from each of the parents, heterozygous, capital p, lower p.

03:38 Due to have a wild type allele, it's going to show all wild phenotype.

03:43 Now for f2, if you have this cross, capital p, lower p, and f2 is going to show three to one ratio.

03:54 So according to law of segregation, capital p and lower p separate from each other.

03:59 And then same for the other parent.

04:06 So capital p, homozygous, heterozygous, heterozygous, and homozygous lower p.

04:14 So all three with dominant allele will show a wild type, wild type three.

04:24 The last one, homozygous lower p, show platinum.

04:36 Homozygous recessive show recessive phenotype.

04:43 And platinum is one out of four.

04:46 So it's a three to one ratio.

04:48 This is consistent with our first cross.

04:51 Now let's move on to the second cross.

04:53 The second cross is wild type crossed with allusion.

04:58 So basically it's the same cross, but we're going to use a different key a.

05:07 So again, parent number one wild type is homozygous capital a and allusion is recessive homozygous lower a.

05:16 So that goes into the box of the table.

05:23 Now again, it's the same cross with f1, 100 % heterozygous capital a lower a.

05:32 And this is why it shows wild type.

05:35 Now for f2, and then you have two heterozygous parents.

05:39 Again, it is going to show the same punnett square with three of them have at least one dominant a wild type and homozygous lower a, one out of four allusion.

05:55 So this is basically the same punnett square as the first cross.

06:02 I'm just replacing p with a.

06:04 So it's again, wild type to allusion three to one.

06:08 The last cross is interesting because now we have two different gene involved.

06:13 So let's take a look at the genome type.

06:16 So platinum has homozygous recessive for p, but it actually is homozygous dominant for a.

06:26 So the platinum actually has a genotype of homozygous capital a, but with a homozygous lower p, because when it comes to gene a, it's actually wild type.

06:45 Now, then the other parent's allusion is the opposite.

06:53 It has homozygous lower a because you have homozygous recessive show recessive phenotype, but it comes to the p gene, it's homozygous dominant capital p.

07:03 So you can see that now we can fill in the last two box of the table.

07:08 Platinum has homozygous dominant a, homozygous recessive p, and allusion is the opposite, homozygous lower a and homozygous capital p.

07:19 Now for f1, simply just one allele from each of the parent.

07:28 So dominant a, recessive a, lower p, and capital p.

07:35 So heterozygous is actually wild type because for both gene you have a dominant a and dominant p.

07:42 Although it is a heterozygous for both gene, but it shows a wild type phenotype due to the dominant allele.

07:50 Now, let's do this f2.

07:53 So again, you have intercross between f1.

07:58 So both parents are heterozygous.

08:00 So this is another f1.

08:02 So according to our very typical dihybrid cross from mendel's, the hybrid cross, you can see that i'm making a bigger...

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