Title: Inheritance of gender linked features

Target Group

A student of the 8th grade of elementary school.

Core Curriculum

The general aim of education

Students discuss the inheritance of gender‑related features.

Criteria for success:

• explain what gender‑related features are;

• provide examples of gender linked diseases;

• on the selected example, you will discuss the phenomenon of inheritance of gender‑related traits;

• you will examine an example family tree to find a pattern of inheritance of gender‑related features.

Key Competences

• Communication in the mother tongue;

• Communication in foreign languages;

• Mathematical competence and basic competences in science and technology;

• Digital competence;

• Learning to learn;

• Social and civic competences.

Methods / techniques

Lecture, presentation, lectures, didactic discussion, subject exercises.

Individual work, work in pairs, work in groups and collective work.

Teaching aids

• abstract;

• tablets / computers;

• interactive or traditional board.

Lesson phases

Introduction

1. The teacher gives the subject and the purpose of the lesson in a language that the student understands as well as the criteria for success.

2. The teacher gives the topic of the lesson, the students write it in their notebooks.

Realization

1. The teacher defines the concept of gender‑related traits and explains that they include diseases caused by the presence of a defective gene copy conditioning a feature and located within the X chromosome.

2. The teacher presents an interactive illustration and discusses the pattern of inheritance of gender related traits by offspring of a healthy man and woman who is the carrier of a faulty allele.

3. The teacher divides the class into groups. The students' task is to trace the inheritance of a selected feature or traits by the offspring of a specific pair. Instructors are assigned to each team for one of the following cases:

• a sick man and woman who is not a carrier of a defective gene;

• a sick man and a woman who is the carrier of a defective gene;

• healthy man and sick woman;

• a man suffering from one disease and a woman who is the carrier of a gene that determines the occurrence of another disease.

4. Each group reports the obtained results. The other students and the teacher complete the statements of colleagues, correct any mistakes.

5. The students together with the teacher analyze the family trees of the royal families of Europe and discuss the scheme of inheriting hemophilia.

6. Students, working in pairs, perform „exercise 1” and „exercise 2”. The teacher monitors the work of the pupils, helps them in case of difficulties.

7. Students independently solve interactive exercises checking the level of mastery of knowledge learned during the lesson.

Summary

Students ask questions, ask for additional explanations and complete the notes.

Homework

Imagine that you have the opportunity to interview an academic - a specialist in the field of today's lesson. What questions would you like to ask him? Write them down.

Explain why women are less likely to suffer from sex‑linked diseases than men.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Sex linked traits, inheritance of gender sex traits

Sex linked traits determined by genes located on the X chromosome are determined (in the case of a determinate sex, as in a human, by the XY system). These traits are inherited in the same way as sex. They are not passed on to the offspring independently, but along with other genes located on the X chromosome.

The most famous traits of a sex‑linked disorder are the inability to properly distinguish colours (colour‑blindness) and hemophilia – a disease, manifested by congenital abnormalities in blood coagulation. The appearance of these traits is conditioned by the recessive allele, which is why they occur relatively rarely in the population. In addition, these characteristics are less likely to occur in women than in men. Men can get a recessive allele from their mothers along with their X chromosome. This is enough to reveal the characteristic, because on the Y chromosome there is no corresponding dominant allele. In order for a woman to show a sex linked traits, she would have to inherit two recessive alleles, one for each parent. Women who are heterozygous for sex linked traits and have a dominant allele and a recessive allele in their genotype, are referred to as carriers. In their phenotype, the recessive allele usually does not reveal itself, but they can pass it on to their children.

Daltonism is one of the kinds of colour blindness, characterized by incorrect perception of green colour and frequent confusion with red. The cause of colour blindness is the recessive allele of a gene located on the X chromosome. The dominant D‑element of the same gene determines the correct perception of colours. Men mainly suffer from colour blindness (8% of the population) who received a recessive allele from their carrier mothers. Among women, only 0.5% are colour‑blind. There are two recessive alleles in their genotype, one inherited from the mother and the other from the father.

Hemophilia it is a very rare genetic defect that does not result in selected blood coagulation factors in the body. It occurs in 1 in 10 thousand people. Their bodies are often bruised and they bleed from the noses. Even minor injuries cause inflammation and pain in the muscles and joints. Treatment of hemophilia patients involves the administration of synthetic blood coagulation factors throughout their lives.

Hemophilia is inherited in the same way as colour blindness. It is conditioned by the recessive h gene located on the X chromosome.

• Sex linked traits, such as colour blindness and hemophilia, are conditioned by recessive alleles of genes located on the X chromosome.

• Sex linked traits are much more common in men than in women.