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Lineage and family tree

Source: licencja: CC 0.

Link to 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.

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Nagranie abstraktu

Lineage and family tree

The inheritance of selected traits, e.g. blood groups, can be represented in subsequent generations using a family tree. It is a schematic record of the way inheritance of a given feature within a related group of people. In order to create such a tree, it is necessary to determine who showed the trait we were interested in in particular generations and who inherited it. After saving the tree, we can determine the phenotypesphenotypephenotypes and genotypesgenotypegenotypes of individual family members and the probability of the appearance of the examined feature in subsequent generations.

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Ilustracja interaktywna przedstawia trzy schematy dziedziczenie chorób uwarunkowanych genetycznie. 1. Diagram of inheritance of genetic diseases conditioned by the presence of the dominant allele, 2. Diagram of inheritance of the carrier of the recessive allele determining the occurrence of a genetic disease, 3. Diagram of inheritance of genetic diseases conditioned by the presence of the recessive allele in the case where both parents are heterozygous
Inheritance of genetically determined diseases
Source: ABO_system_codominance.svg, GroMar Sp. z o.o., licencja: CC BY-SA 3.0.

Huntington's disease is caused by mutation of a single gene in chromosomechromosomechromosome 4. The mutant gene is dominant. It creates a protein with toxic properties that is deposited in nerve cells and causes them to die. The disease consists of progressive dementia and is usually manifested after the age of 35. Usually, the holders of the defective gene already have offspring. Statistically, half of the offspring of a person with a defective allelealleleallele will inherit this disease.

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Inheritance of Huntington's Disease in an example family
Source: Anita Mowczan, licencja: CC BY 3.0.
Task 1

Was the mother of the line shown in Figure 5 homo- or heterozygous for the gene that causes Huntington's disease? Based on what fact can this be determined?

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Exercise 1
Wersja alternatywna ćwiczenia: What is a family tree? Indicate the correct answer. Możliwe odpowiedzi: 1. one of the terms denoting a genetic cross, 2. a method of a schematic record of the inheritance of a given feature within a family, 3. the way in which the genotype of future offspring can definitely be determined, 4. one of the terms denoting a genetically determined disease
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Exercise 2
Wymyśl pytanie na kartkówkę związane z tematem abstraktu.
Diagram of inheritance of the carrier of the recessive allele determining the occurrence of a genetic disease
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.

Summary

  • The inheritance of selected traits, e.g. blood groups, can be represented in subsequent generations using a family tree.

Keywords

inherited diseases, lineage, family tree

Glossary

allele
allele
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Nagranie słówka: allele

allel – jedna z dwóch lub więcej odmian danego genu, odpowiedzialnego za wytworzenie konkretnej cechy organizmu; allele danego genu są położone w określonym miejscu na chromosomie

chromosome
chromosome
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Nagranie słówka: chromosome

chromosomy – podziałowa postać DNA; wydłużone, pałeczkowate struktury powstające z nici DNA w jądrze tuż przed podziałem komórki i widoczne w czasie podziału jądra

phenotype
phenotype
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Nagranie słówka: phenotype

fenotyp – zespół wszystkich cech budowy i fizjologii organizmu wyznaczanych przez genotyp i środowisko

genotype
genotype
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Nagranie słówka: genotype

genotyp – zespół wszystkich genów danego osobnika warunkujący jego cechy; pojęcie czasem (w krzyżówkach genetycznych) używane w odniesieniu do jednej lub kilku par alleli