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Inheritance of blood groups, Rh inheritance

Source: Senior Airman Philip Bryant, domena publiczna.

Link to the lesson

Before you start you should know
  • genes exist in varieties called alleles that can be dominant or recessive;

  • the A and B antigens present on the surface of erythrocytes determine the group of human blood;

  • serological conflict can occur when the mother has a blood group Rh- and the child Rh+.

You will learn
  • describe the inheritance of selected traits in humans;

  • analyze inheritance schemes for determining the phenotype and genotype of offspring (blood groups in the ABO, Rh system);

  • analyze the inheritance of the blood group in example families.

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Nagranie dźwiękowe abstraktu

Inheritance of blood groups

Quite often, one gene has more than two alleles. Alleles present in more than two forms are called multiple allelesmultiple allelesmultiple alleles. A good example of a gene having several varieties is a gene that determines blood groups in humans. It occurs in three alleles: IIndeks górny A, IIndeks górny B, i. The first two, as indicated by the record, are the dominant alleles, and the third - the recessive allele. In addition, alleles IIndeks górny A, IIndeks górny B they are equal to each other, which means that one does not dominate the other. Each man inherits only two alleles conditioning a specific blood group: one after father and the other after mother.

In ABOABOABO system four blood types occur: A, B, AB and O.

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Genotypes conditioning blood groups
Source: Dariusz Adryan, licencja: CC BY 3.0.

Blood group O is conditioned by genotype ii and group AB by genotype IIndeks górny AIIndeks górny B. Groups A and B can be determined by two genotypes. A person with blood group B may have a genotype IIndeks górny BIIndeks górny Bor IIndeks górny Bi. Another, with group A, may have a genotype IIndeks górny A IIndeks górny A or IIndeks górny A i . To predict blood groups of the offspring, genetic crosses should be written.

Task 1

Determine which blood group the children of the marriage in which the woman has blood type 0 and the male AB will have. Save and explain the genetic cross.

Inheritance of the Rh factor

Rh factorRh factorRh factor is a substance, also called D antigen, appearing on the surface of erythrocytes in 85% of people. In humans, the gene in two variants corresponds to the inheritance of the Rh factor: Rh+Rh-. The Rh+ allele is the dominant allele and the Rh- allele is the recessive allele. Accordingly, people who have the Rh+ Rh+ or Rh+ Rh- genotype have Rh factor (D antigen) on the surface of the erythrocytes and people who have the Rh‑Rh- genotype don't have Rh factor.

The offspring of a man who is heterozygous with the Rh + blood group and a woman with the Rh- blood group may have Rh+ or Rh- blood groups. If the Rh factor is incompatible between the mother and her unborn child, i.e. when the Rh‑mother's child, inherits the Rh+ from the father, it results in a serological conflictserological conflictserological conflict.

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Inheritance of Rh in humans
Source: Anita Mowczan, licencja: CC BY 3.0.

It only happens when the mother is a Rh‑recessive homozygote. When a father gives Rh+ to his child, their child will be heterozygous, which means that a Rh factor will appear in his blood.

Task 2

Determine which genotypes and phenotypes can the children have of a marriage, in which both parents have a Rh+ blood group. Consider all possibilities.

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Table for the compatibility of blood groups including the Rh factor. It's good to see your blood group and Rh factor in case of urgent blood transfusions or organ transplants
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.

It is worth noting your blood group. Adults who know theirs can respond to calls for specific blood groups, especially rare ones. On the basis of the knowledge of the principles of inheritance of blood groups, paternity can be excluded in some cases.

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A person with blood group O can be a donor for other groups, people with groups A and B can be donors for people with blood group AB
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.
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Exercise 1
Wysłuchaj nagrania abstraktu i zastanów się, czego jeszcze chciałbyś się dowiedzieć w związku z tematem lekcji.
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.
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Exercise 2
Ćwiczenie Wyjaśnij kluczowe pojęcia związane z tematem abstraktu.
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Exercise 3
A woman with blood type AB is expecting a baby with a man who also has an AB blood group. What kind of blood group will their child not have? Możliwe odpowiedzi: 1. O, 2. A, 3. B, 4. AB
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Exercise 4
Determine by means of appropriate genetic crosses what the blood group of the children will be if the parents have, one of whom has blood group O and the other - blood group A, with both parents on the surface of erythrocytes D antigen. Indicate all the correct answers. Możliwe odpowiedzi: 1. O Rh-, 2. O Rh+, 3. A Rh-, 4. A Rh+, 5. AB Rh+, 6. AB Rh-

Summary

  • Most human traits are conditioned by a set of many genes that occur in the form of two or more alleles.

  • Few human traits inherit monogenes (they are conditioned by one gene that can exist in two or more alleles); belong to them, among others blood group and Rh factor.

  • Blood groups in the ABO system are conditioned by the presence of two of the three alleles: I Indeks górny A  Indeks górny koniec, I Indeks górny B  Indeks górny koniec and i.

  • The presence of the Rh factor in human blood depends on two alleles: the dominant allele – Rh+ and the recessive allele – Rh-.

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Grafika przedstawiająca tablicę szkolną, na której znajdują się zdania do dokończenia. Finish selected sentences. 1 It was easy for me (uzupełnij). 2 It was difficult for me (uzupełnij). 3 Today I learned (uzupełnij). 4 I understood that (uzupełnij). 5 It surprised me (uzupełnij).
How was this lesson? Did you like it? Finish selected sentences.
Homework
Task 3.1
Czy rodzice z grupami krwi A i B mogą mieć dzieci z grupą krwi O?
Czy rodzice z grupami krwi A i B mogą mieć dzieci z grupą krwi O?

Keywords

blood group, Rh factor, alleles

Glossary

multiple alleles
multiple alleles
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Nagranie dźwiękowe słówka

allele wielokrotne – allele genu występujące w populacji w więcej niż dwóch postaciach, np. allele warunkujące grupę krwi u człowieka (IIndeks górny A, IIndeks górny B, i )

Rh factor
Rh factor
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Nagranie dźwiękowe słówka

czynnik Rh – gen, który występuje na powierzchni czerwonych krwinek u 85% ludzkiej populacji

serological conflict
serological conflict
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Nagranie dźwiękowe słówka

konflikt serologiczny – może wystąpić w okresie ciąży między matką Rh- uczuloną na czynnik Rh i dzieckiem Rh+; jego skutkiem jest niszczenie erytrocytów dziecka, co może doprowadzić do obumarcia płodu i jego poronienia

ABO
ABO
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Nagranie dźwiękowe słówka

układ ABO – jeden z głównych układów grupowych krwi człowieka, oparty na obecności na powierzchni erytrocytów antygenów A i B