Can somebody tell me how you get the answer ? Thx in advance

[Sara Taboni Miller]

[Lord Antares]

We're not allowed to give straight answers here. You're supposed to give your line of thinking and what you think is the answer and why and people will guide you to the right answer. You're supposed to give it, though.

[Sara Taboni Miller]

10 minutes ago, Lord Antares said:

We're not allowed to give straight answers here. You're supposed to give your line of thinking and what you think is the answer and why and people will guide you to the right answer. You're supposed to give it, though.

Oh gotcha , Well I thought it was the number A, since Rh + is dominant and Rh- recessive, and all the other answers have the rh- .. but it's actually 0 Rh- (E) so I don't understand how it's inherited. 

[Function]

If you consider that the rhesus factor is dominantly inherited, consider the possibility of one parent having genotype Rh +/-, thus he will produce the rhesus factor, and will thus be considered "Rh+", but it is very well possible that he has another allele that "is" Rh-. If he pairs with a person with Rh- (who can only have genotype Rh -/-, else this person would have Rh +/- or Rh +/+ and would undeniably produce the rhesus factor, thus "be" Rh+, which is not the case), the following combinations are possible:

Rh+ / Rh- = Rh +/- = Rh+

Rh- / Rh- = Rh -/- = Rh-

So you're not going to base your answer on rhesus factor.

Do you know something on the inheritance of blood cell antigenes (A, B) and plasma antibodies (anti-A, anti-B) and what role O plays in there? Neglecting the rhesus factor, someone with blood type A can have 2 different genotypes. Do you know which?

Edited August 20, 2017 by Function

[Sara Taboni Miller]

30 minutes ago, Function said:

If you consider that the rhesus factor is dominantly inherited, consider the possibility of one parent having genotype Rh +/-, thus he will produce the rhesus factor, and will thus be considered "Rh+", but it is very well possible that he has another allele that "is" Rh-. If he pairs with a person with Rh- (who can only have genotype Rh -/-, else this person would have Rh +/- or Rh +/+ and would undeniably produce the rhesus factor, thus "be" Rh+, which is not the case), the following combinations are possible:

Rh+ / Rh- = Rh +/- = Rh+

Rh- / Rh- = Rh -/- = Rh-

So you're not going to base your answer on rhesus factor.

Do you know something on the inheritance of blood cell antigenes (A, B) and plasma antibodies (anti-A, anti-B) and what role O plays in there? Neglecting the rhesus factor, someone with blood type A can have 2 different genotypes. Do you know which?

I know that a person  with A blood type will have A anitigens and anti-B antibodies, and a person with B blood type will have anti-A antibodies but B antigens . With that been said , I also know that the two parents have AA and BA, so the only blood type that should be inherit it's either A or AB , but even B shouldn't be right then.. that's what I don't get of this question .. as well as 0, which is the right answer .. 

[Function]

Why do you think that the person with blood type A has genotype AA?

Hint: O (genotypically commonly denoted as "i") is inherited recessively, A and B are inherited dominantly.

See it as follows: the "O-gene" does not allow the person to produce any antigenes on the cell surface of the red blood cell. But, if that person has any other gene (A or B), they will create the respective antigenes and will thus be considered to be of that blood type. Do you get this? The person may have both O and A antigenes, but will be considered of blood type A since he makes A antigenes on the red blood cell surface.

 

Sidenote considering antibodies: in development of the immune system, all potential anti-A antibodies will be eliminated (so that his immune system won't attack his own blood cells), and only anti-B antibodies remain in the blood plasma. (Analogous: a person with blood type AB has both antigenes A and B and in the development of the immune system, antibodies anti-A and anti-B will be eliminated very early in the development of immune cells, leaving no antibodies in the blood plasma, making persons with blood type AB the ideal blood plasma donors, but the less appropriate blood pack (cells) donors)

Edited August 20, 2017 by Function

[Sara Taboni Miller]

4 minutes ago, Function said:

Why do you think that the person with blood type A has genotype AA?

Hint: O (genotypically commonly denoted as "i") is inherited recessively, A and B are inherited dominantly.

Isn't A and B equal to AA and BB respectively ?  

         AB 

A     AA AB  this is the column that I thought was the right one .. A and AB get AA and AB .. no? So for sure they won't get O ( answer E right ) but then why B (answer C)?

[Function]

No, A and B are AA or Ai, and BB or Bi, respectively, "i" representing an allele lacking of genes coding for antigenes A or B, thus resulting in O (people with blood type O have red blood cells that do not express antigenes A or B; it is important to know that O antigenes do not exist, it simply represents the lack of antigenes A or B).

So you must consider the possibility of the parent with blood type A being of genotype Ai, or AA.

Ai + AB = AA (= A), AB (= AB), Ai (= A), or Bi (= B)

AA + AB = AA (= A), or AB (= AB)

Do you get this?

Edited August 20, 2017 by Function

[Sara Taboni Miller]

1 minute ago, Function said:

No, A and B are AA or Ai, and BB or Bi, respectively, "i" representing the lack of genes coding for antigenes A or B, thus resulting in O (people with blood type O have red blood cells that do not express antigenes A or B; it is important to know that O antigenes do not exist, it simply represents the lack of antigenes A or B).

So you must consider the possibility of the parent with blood type A being of genotype Ai, or AA.

Ai + AB = AA (= A), AB (= AB), Ai (= A), or Bi (= B)

AA + AB = AA (= A), or AB (= AB)

Do you get this?

Oh yes I got it know, and therefore the only type of blood which could never been inherited from A and AB is indeed O . Right ? 

[Function]

That's right.

As per exercise, could you give me all possible combinations that 2 parents could have, if you'd want a child with blood type O (ii)?

EDIT: OP felt the need to solve exercise in PM; answer is given:

• ii (O) + ii (O)
• Ai (A) + ii (O)
• Bi (B) + ii (O)
• Ai (A) + Bi (B)
• Ai (A) + Ai (A)
• Bi (B) + Bi (B)

Edited August 20, 2017 by Function