Question

Co-dominance, Multiple Alleles, and Sex-linkage

1. Abby is unsure of the father of her daughter, Susie, and wants a quick way to find out which of the men she has dated it could be. Her blood type is AB, and her daughter’s is B. Of the possible men Dalton, has AB type blood, Jordan has O type blood, and Wyatt has A blood. Use the clues here and for each part of this problem to see who the father is. *** Be sure to answer all parts of each question.

• For blood type, A (I^AI^A or I^Ai) and B (I^BI^B or I^Bi) blood types are dominant to O (ii), and AB (I^AI^B) is codominant, meaning that both A and B proteins are expressed.
• The gene for color vision is sex-linked on the X chromosome, and having color vision (Females: X^BX^B or X^BX^b, Males: X^BY) is dominant to being color blind (Males: X^bY, Females: X^bX^b).
  1. Give the genotypes for each individual for blood type and then for color blindness. You may not be able to figure out all parts with the information provided. Put a “?” in the position for any alleles that you cannot determine, but you should be able to put at least part of the genotypes for all individuals based on the information provided above and additional information provided in the problems below.
     1. Abby’s Genotypes
        1. Blood Type:
        2. Vision:
     2. Susie’s Genotypes
        1. Blood Type:
        2. Vision:
     3. Dalton’s Genotypes
        1. Blood Type:
        2. Vision:
     4. Jordan’s Genotypes
        1. Blood Type:
        2. Vision:
     5. Wyatt’s Genotypes
        1. Blood Type:
        2. Vision:

2. Can you tell from the information given in the word problem above who the father is? Can you at least eliminate one man? Why or Why not?

3. Wyatt insists that he cannot be the father. He provides his parents’ blood types – both are AB. Is Wyatt correct that he is not the father? How do you know? *Hint, do a cross for his parents and determine what his actual genotype is.

4. Abby is hoping that Dalton is the father. She argues that because Dalton is the only man who color blind, just like Susie, he must be the father. Who is the father (Can you tell?)? How do you know or why can’t you tell?

Answer 1

Information regarding the inheritance of blood type and colorblindness is given. Blood type inheritance shows codominance and is also an example of multiple gene inheritance. Colorblindness is a sex-linked recessive trait or X-linked trait i.e. expressed only when individual has recessive pair in females and one copy in males.

In the upper half, the information of blood types or groups of each individual is given but no information is given regarding anyone being colorblind.

But question also says, we have to utilize the information given below in the question. So, we will consider both the information and answer the questions.

Ans 1) Abby's Genotype :

Blood group = AB . Genotype = iAiB

Vision = above information says nothing about colorblindness so Accordingly,

Genotype = XBXB

But in Information below in question where Abby is arguing that Dalton is the father. There is given that Susie is colorblind, it is possible only when mother is either colorblind or is carrier for it. As no information for Abby being colorblind is given, so she must be a carrier.

So her genotype is = XBXb

Conclusion = blood= iAiB . Vision = XBXb ( carrier)

Ans 2) Susie's genotypes :

Blood group = B

Genotype = iBiB or iBi

Vision = according to above half question = XBX_ { _ = B or b}

But according to the below half in which Abby is arguing about Dalton being father, she also says that Susie is Colorblind. So, genotype = XbXb.

Conclusion = blood = iBiB or iBi .

Vision = XbXb (Colorblind)

Ans 3) Dalton's genotype :

Blood group = AB

Genotype = iAiB

Vision = According to above half of question = XBY.

But in below in which Abby is arguing about Dalton being father she says Dalton is colorblind as Susie. So,

Genotype = XbY.

Conclusion = Blood= iAiB ; Vision = XbY ( colorblind)

Ans 4) Jordan's genotype :

Blood group = O

Genotype = ii

Vision = No, information given of being his colorblind. So, genotype = XBY

Ans 5) Wyatt's genotype :

Blood group = A

Genotype = iAiA or iAi

But as per the information given in the a2 part of question that his parents are AB. So, he have blood group A as iAiA. Cross is shown in Ans a2.

Vision = No, information of him being colorblind is given so, genotype = XBY.

Conclusion = blood group =iAiA ; vision=XBY

Ans a1) yes, as per the information concluded we can predict DALTON to be the father as per his blood group and colorblindness. Because Abby and Dalton has blood group AB and their is 1/4 or 25% probability of their child to have blood group B ( iBiB).

Their is 1/2 chance also of their daughter being colorblind, as Susie is colorblind and Dalton is also a colorblind that means Abby is also a colorblind. So,

XBXb X XbY

	XB	Xb
Xb	XBXb	XbXb
Y	XBY	XbY

So, we can eliminate Wyatt and Jordan as they are not colorblind.

Ans a2) yes, Wyatt may be correct as both his parents have AB blood group. And their is 1/4 chance of offspring be AA. So, he can be that or AA.

iAiB X iAiB

	iA	iB
iA	iAiA	iAiB
iB	iAiB	iBiB

So, Accordingly he can't be the father as Susie has blood group B. And a Homozygous A can't produce a B blood group chlid with AB.

Ans a3) given that, Dalton is colorblind = XbY.

Just like Susie = XbXb (genotype)

When Susie is colorblind, then Abby must be colorblind or is a carrier but no information of Abby being colorblind is given then she must be a carrier of colorblind trait = XBXb

Yes, we can tell by using the above information that DALTON is the FATHER. As per his blood group and of him being colorblind.

While others Jordan and Wyatt can't be father as

Jordan can produce chlid with Abby who will have blood group B (iBi) but he is not a colorblind as Susie as per no information is given regarding him being colorblind.

Wyatt can't be the father as per his blood group (iAiA) analysed from his parents (AB) he can't produce a child with B blood group and no information of him being colorblind is given. Although he can't be father because he can't produce a child with B blood group so being a colorblind or not does not matter.

Thank you...???