Title: Production of proteins in the cell

Target group

8th‑grade students of elementary school (new core curriculum).

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.

Lesson aim

Students explain how the order of nucleotides in a strand of DNA affects the synthesis of protein in a cell.

Criteria for success

• explain what a codon is and how it's built;

• discuss the process of protein synthesis in a cell;

• give a sample nucleotide sequence in the codon and find in the table the name of the amino acid coded with this sequence.

Key competences

• communicating in the mother tongue;

• communicating in a foreign language;

• digital competence; 

• mathematical competence and basic competences in science and technology;

• learning to learn;

Methods/forms of work:

Work with text, mini‑lecture, case study, presentation, exercises concerned.

Individual work, work in groups and collective work.

Teaching aids:

• abstract;

• interactive whiteboard or traditional blackboard;

• tablets/computers.

Lesson phases

Introduction

1. The teacher determines the purpose of the lesson and informs the students about its planned course. Presents the criteria for success.

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

Realization

1. The lecturer explains that the length and type of protein synthesized in a cell depends on the amount of amino acids and the order in which they are arranged in the DNA strand; draws attention to the structure of the protein, its phenotypic properties. This information is stored in the genetic code by means of codons, ie triples of successive nitrogen bases.

2. The teacher displays the illustration „DNA sequence and the corresponding protein sequence”. The teacher discusses the structure of the code fragment on the basis of which protein is synthesized (at the beginning a codon denotes the start of synthesis of a new protein, then codons denoting successively attached amino acids and finally - a codon denoting termination of synthesis).

3. The teacher divides the class into groups of three or four. Students analyze the illustration of „Selected codons and their meaning” and then complete „exercise 1”

4. The groups subsequently present the effects of the work, writing on the array of nucleotide sequences they designed and naming the codons coded for by the individual codons. The other students check whether there are no errors in the nucleotide sequence, in particular whether there are no codons in the middle of the sequence coding for an additional „START” or „STOP” signal.

5. The lecturer displays an interactive illustration „What amino acids code the following codons?”. Then draws students' attention to the fact that the majority of amino acids are coded by several codons. Often the same amino acid is encoded by several codons that differ only in the last nucleotide. This largely prevents situations where, by random error during the replication or reading of the DNA, one of the amino acids is replaced with another, which may result in a change in the properties of the synthesized protein.

6. Students independently solve interactive exercises, the aim of which is to repeat and solidify knowledge learned during the lesson.

Summary

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

The student explain the relationship between the gene, protein and body traits.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Production of proteins in the cell

Proteins are made of amino acids that combine with each other in very long chains. Each protein is characterized by a specific number of amino acids and the order in which they are arranged. The function of protein in the body depends on the aminoacid composition. The type and order of amino acids is determined by the sequence of nucleotides in the gene.

The nucleotides that make up the gene are read in threes. One of the three nucleotides corresponds to one amino acid. The three nucleotides are the basic coding unit in the genetic code, called codon.

The genetic code consists of 64 codons. 61 of them encode amino acids. One of them is a START codon. It determines the amino acid called methionine, from which the synthesis of each protein begins. Three other codons, are called STOP codons, they do not correspond to any amino acid. Their presence is a signal to stop protein production. Such a signal in the form of a codon is necessary because the genetic code contains no gaps or separating characters. If STOP codons did not exist, protein synthesis could go on forever.

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

• The genetic code is in threes, meaning that one amino acid is coded by three nucleotides called codons.

• The gene contains information about the structure of a specific protein; the order of codons in the gene determines the order of amino acids in the protein.

• The genetic code is universal; Genetic information is recorded in all organisms in the same way.