Topic: Mutations and their causes

Target group

8th‑grade students of elementary school

Core curriculum

General requirements

I. Knowledge of biological diversity and basic biological phenomena and processes. Student:

2. explains biological phenomena and processes occurring in selected organisms and in the environment.

Specific requirements

V. Genetics. Student:

10. provides a general definition of mutations and lists the reasons for their occurrence (spontaneous and mutagenic mutations); gives examples of mutagenic agents (UV radiation, X‑rays, components of tobacco smoke, mold fungus toxins, HPV virus);

11. gives examples of human genetic diseases determined by mutations (cystic fibrosis, phenylketonuria, Down's syndrome).

General aim of education

The student will learn what mutations are and what they are called

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• to explain the difference between the inherited genetic variation and non‑inherited variation and give examples;

• to explain what mutations are and what their connection with genetic variation is;

• to give examples of mutagens.

Methods/techniques

• expository

  • talk.

• activating

  • discussion.

• exposing

  • exposition.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers.

Lesson plan overview

Before classes

• Students get acquainted with the content of the abstract. They prepare to work on the lesson in such a way to be able to summarize the material read in their own words and solve the tasks themselves.

Introduction

• The teacher explains the aim of the lesson and together with students determines the success criteria to be achieved.

Realization

• The teacher explains that these mutations can be divided into structural mutations (causing the change of genetic material in chromosomes) or numerical (causing a change in the number of chromosomes in the cell).

• Participants familiarize themselves with the content presented in the interactive illustration. Then the teacher discusses the issues with the students.

• The teacher explains that chromosomal mutations rely on changing the structure of chromosomes, while genomic mutations on changing the number of chromosomes.

• The lecturer discusses the main factors affecting the possibility of mutations. It also informs that a healthy organism has mechanisms to protect against DNA damage or errors when copying it. Usually, these mechanisms fail only with a significant increase in mutagenic factors (eg cancers caused by frequent and long‑term exposure to solar radiation or cigarette smoke are the result of the development and division of mutated somatic cells).

• Students perform exercises and commands. The teacher checks and supplements the answers, providing students with the necessary information. Provides feedback..

Summary

• The teacher briefly presents the most important issues discussed in class. He answers the additional questions of the proteges and explains all their doubts. Students complete notes.

• The teacher asks a willing student to summarize the lesson from his point of view. He asks other students if they would like to add anything to their colleague's statements.

Homework

• Listen to the abstract recording at home. Pay attention to pronunciation, accent and intonation. Learn to pronounce the words learned during the lesson.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Mutations and their causes

During copying of the DNA strand errors happen. As a result of those errors, genetic information changes. Those sudden changes to the genetic material of the cell, which are lasting ones (they become permanent), are called mutations. Most often, permanent changes in the DNA take place not as a result of an error in copying of the strand, but as a result of external factors, called mutagens. They can not only cause changes in the sequence of nucleotides (gene mutations), but also in the build and number of chromosomes (chromosome and genome mutations. Mutagens are physical factors, e.g. UV radiation; chemical factors, e.g. some chemical compounds in exhaust fumes (dioxines) and cigarette smoke; and biological factors, such as some viruses and products of the metabolism of mould.

Mutations that take place in individual genes are called gene mutation. Those are the changes in the sequence of individual nucleotides in the DNA. Those can appear in any given DNA section.

Other types of mutations are chromosome and mutations which are based on the change of the structure of chromosomes, caused mainly by mutagenic agents. As a result of e.g. ionizing radiation, chromosomes can break into pieces, which can rearrange themselves in a different configuration. Changes in number of chromosomes (genome mutations) occurs when an individual either is missing a chromosome from a pair or has more than two chromosomes of a pair (e.g. Down syndrome).

Majority of small changes in the genetic material is neutral. Some of them are beneficial and give the organisms an upper hand over those, which did not undergo that particular mutation. Very few mutations are dangerous. Sometimes a change in one nucleotide in the DNA sequence can cause an incorrect function of an entire gene, and, as a result, the creation of an incorrect protein (or lack of a protein) and, in consequence, a genetic disease.

Organism has many ways of protecting itself from DNA damage. However, sometimes those mechanisms fail. Mutations can spread to offspring cells during the next reproduction. Mutagens appearing in somatic cells are not inherited by the offspring that is created as a result of sexual reproduction, but they can e.g. cause cancer in organisms where they took place. If a mutation is in the DNA of reproductive cells, it will be transferred to the offspring.

• Mutations change the genetic information; they can happen spontaneously, as a result of an error in the process of copying DNA, or can be caused by mutagenic agents.

• Gene mutations take place in individual genes and are based on changes in the sequence of nucleotides in the DNA.

• Chromosome and genome mutations are based on changes in the build and number of chromosomes, respectively.