Topic: How genetic information is written

Author: Leokadia Stalewicz

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:

1. presents the structure and role of DNA.

General aim of education

The student acquires knowledge and skills about the topics discussed in the classes

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• explain how proteins are formed on the basis of DNA, and then specific features of the organism;

• distinguish the concepts of genetic code and genetic information;

• show how to store genetic information in DNA;

• describe the genetic code.

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 gives the topic, the goals of the lesson in a language understandable for the student, and the criteria of success.

• The teacher reminds the participants of the classes what subject area the lesson will concern.

Realization

• The lecturer explains what the genetic code is and how the genetic information is recorded using the nucleotide sequence. The teacher explains that changing one nucleotide can change the information stored in the DNA molecule (possibly in the RNA molecule - for some viruses).

• Participants familiarize themselves with the content presented in the interactive illustration „Differences in the genetic code”. Then the teacher discusses the issues with the students.

• The teacher explains that homozygous organisms that have two copies of a defective gene do not produce melanin at all in somatic cells. The teacher also informs that in some cases the differences in information transmitted by a given gene are not important from the point of view of health and life (eg eye or hair color), in others - lead to serious disorders of tissues and organs.

• The teacher displays the illustration from the abstract, and explains how the genes, through the proteins they encode (including enzymes and hormones) condition the occurrence of specific features of the organism.

• Students, working individually or in pairs, carry out interactive exercises to check and consolidate knowledge learned during the lesson. Selected people discuss the correct solutions for interactive exercises. The teacher completes or corrects the statements of the proteges.

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.

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.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

How genetic information is written

Features of an organism depend on the type of its proteins. The instruction of protein construction, i.e. genetic information, is written in the DNA. A DNA molecule is made up of billions of nucleotide pairs. Nucleotide sequence is not random. It is a special code. The alphabet of this code is made up of just 4 characters that are actually 4 nitrogenous bases, which form 4 types of nucleotides. Depending on the number and sequence of the nucleotide arrangement, the genes that they make up contain instructions for the formation of different proteins. The rules of the code writing are called genetic code.

Human DNA contains more than 20 thousand genes, and almost each of them controls production of a different protein. These include proteins that build structures of the organism, enzymes that enable various chemical reactions in cells, some hormones that regulate the function of tissues and organs and those that control growth and development. For example, eye colour to be created needs a special protein – an enzyme – that can transform colourless substrate into brown melanin. This enzyme is produced based on the instructions contained in the particular gene. The people in whom the gene coding for this enzyme is inactive will have no melanin in their irises. Their eyes will usually be red. This is because blood vessels are visible through colourless iris tissue with no melanin.

In fact, people have eyes of various colours. This diversity is due to the presence of various genes. Each of them contains information regarding how much melanin should be produced in irises. The more melanin, the darker the colour of the eyes. Since the colour of the human iris is determined by several genes, it has an infinite number of variants. Coloured irises are a common trait of all people (with few exceptions), but eye colour is an individual personal feature.

• The genetic code is a way of writing information about the structure of proteins.

• The genetic code is a triplet code, i.e. one amino acid is coded by three nucleotides called a codon.

• The gene contains information about the structure of a specific protein, while the sequence of codons in the gene determines the sequence of amino acids in the protein.

• The genetic code is universal; the genetic information is written identically in all organisms.