Question

The spotting gene dictates the migration of pigment cells in cat coats. The recessive ss genotype has complete migration, the Ss genotype has moderate migration but pigment does not make it to feet and chest, and the SS genotype has low pigment migration where the majority of the pigment is on the back, head, and tail. The orange gene, located on the X-chromosome, dictates whether the pigment is orange X?X? or X?Y, black X?X? or X?Y, or both X?X?. See pictures of cats with corresponding genotypes in Figure 2. ss Ss SS SS X?X? X?X? or X?Y Figure 2 The reason that the calico cat on the right is spotted with orange and black rather than just expressing the dominant allele is because of X-inactivation, a phenomenon in mammals where one of the two X-chromosomes in female cells condenses into an inactive form called a Barr body. The X- chromosome encodes a regulatory RNA called Xist that surrounds the X to be inactivated, which is random, and then recruits histone H2A variant macroH2AZ, which leads to heterochromatin formation.

          The spotting gene dictates the migration of pigment cells in cat coats.  The recessive ss genotype
has complete migration, the Ss genotype has moderate migration but pigment does not make it to
feet and chest, and the SS genotype has low pigment migration where the majority of the pigment
is on the back, head, and tail.  The orange gene, located on the X-chromosome, dictates whether
the pigment is orange X?X? or X?Y, black X?X? or X?Y, or both X?X?.  See pictures of cats with
corresponding genotypes in Figure 2.
ss  Ss  SS  SS
X?X?
X?X? or X?Y
Figure 2
The reason that the calico cat on the right is spotted with orange and black rather than just
expressing the dominant allele is because of X-inactivation, a phenomenon in mammals where one
of the two X-chromosomes in female cells condenses into an inactive form called a Barr body.  The X-
chromosome encodes a regulatory RNA called Xist that surrounds the X to be inactivated, which is
random, and then recruits histone H2A variant macroH2AZ, which leads to heterochromatin
formation.

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The spotting gene dictates the migration of pigment cells in cat coats. The recessive ss genotype
has complete migration, the Ss genotype has moderate migration but pigment does not make it to
feet and chest, and the SS genotype has low pigment migration where the majority of the pigment
is on the back, head, and tail. The orange gene, located on the X-chromosome, dictates whether
the pigment is orange X?X? or X?Y, black X?X? or X?Y, or both X?X?. See pictures of cats with
corresponding genotypes in Figure 2.
ss Ss SS SS
X?X?
X?X? or X?Y
Figure 2
The reason that the calico cat on the right is spotted with orange and black rather than just
expressing the dominant allele is because of X-inactivation, a phenomenon in mammals where one
of the two X-chromosomes in female cells condenses into an inactive form called a Barr body. The X-
chromosome encodes a regulatory RNA called Xist that surrounds the X to be inactivated, which is
random, and then recruits histone H2A variant macroH2AZ, which leads to heterochromatin
formation.

Added by Randall D.

Genetics: A Conceptual Approach

Benjamin Pierce 6th Edition

Chapter 4

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Solved by Expert Katlin Koehn

06/08/2023

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Identify the gene that dictates the pigment migration in cats. The spotting gene dictates the migration of pigment cells in cat coats. The recessive ss genotype has complete migration, the Ss genotype has moderate migration but pigment does not make it to feet Show more…

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Transcript

00:02 So here we have a genetics question where lots of different genes are all working together to determine one single trait.

00:09 So a polygenetic trait.

00:12 So the first gene we have is w where the dominant allele codes for an organism being all white, so that's the only color on them, whereas having two recessive w's is colored.

00:24 Now that color, whatever it is, depends on the other genes.

00:28 So first we have the x chromosome has gene with two alleles b and o.

00:36 So b codes for black and o codes for orange or cream depending on some of the other genes.

00:48 Black can also code for gray depending on other genes, right? and if you are a female and can have two x chromosomes and one of them is b, one of them is o, you will end up more of a calico color.

01:06 And then we have gene d.

01:08 So if you have a dominant allele, then you will have full color.

01:14 So meaning you will be either black or orange depending on what alleles you have on your x chromosomes.

01:22 But if you have two recessive d alleles, you will have a diluted color.

01:26 So meaning that you will be either the gray or the cream color, again depending on what alleles you have on your x chromosomes.

01:35 And then finally we have one more allele, or one more gene, which is p.

01:41 So if you have the n allele on your p gene, there will be no pattern, no pattern for your coloring.

01:54 If you have the e allele, then you will have extensive patterning.

02:02 And finally if you have that p gene and you have one n and one e, then you will have some patterning.

02:13 So with all of that information, we are now going to look at the phenotypes of genotypes based on those phenotypes.

02:22 And so it's going to be important for each one, whether we're looking at a male or a female.

02:29 So for the first one, we're looking at a male who is cream colored with extensive patterning.

02:37 So based on this, we know a few different things.

02:39 First off, if they are a male, we know they have one x chromosome and one y.

02:47 So on your x chromosome, because we're cream, right, that comes from this o.

02:52 So he has an o allele on his only x chromosome...

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