Topic: Structure and biological functions of fats

Target group

Elementary school student (grades 7. and 8.)

Core curriculum:

Primary school. Chemistry.

X. Chemical substances of biological importance. Pupil:

3) describes the structure of a fat molecule as an ester of glycerol and fatty acids; classifies fats in terms of origin, physical state and chemical nature; describes selected physical properties of fats; designs and conducts experiments to distinguish between unsaturated fat and saturated fat.

General aim of education

The student explains the structure and functions of fats.

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.

Criteria for success
The student will learn:

• to classify fats in terms of origin and physical state, giving examples;

• to indicate food products that are a source of fats;

• to indicate the elements included in the composition of fats;

• to classify fat into esters and provide justification;

• to create semi‑structural examples of exemplary fats;

• to call fat based on a semi‑structural formula;

• to analyse the functions of fats.

Methods/techniques

• expository

  • talk.

• activating

  • discussion.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers;

• sheets of gray paper;

• colored markers.

Lesson plan overview

Introduction

1. The teacher hands out Methodology Guide or green, yellow and red sheets of paper to the students to be used during the work based on a traffic light technique. He presents the aims of the lesson in the student's language on a multimedia presentation and discusses the criteria of success (aims of the lesson and success criteria can be send to students via e‑mail or posted on Facebook, so that students will be able to manage their portfolio).

2. The teacher together with the students determines the topic – based on the previously presented lesson aims – and then writes it on the interactive whiteboard/blackboard. Students write the topic in the notebook.

Realization

1. The teacher initiates a conversation introducing the topic. He asks students to think of possible uses of fats apart from food and cosmetics industry. He asks question: „In which products can you find them?”.

2. Students define the concept of fats and discuss tables presenting classification of fat .

3. The teacher presents on the multimedia board the general formula of fats, placed in the abstract. He discusses it, paying special attention to the elements involved in the construction of fats, types of chemical bonds, ester groups and hydrocarbon radicals of fatty acids.

4. The teacher asks students to look at the the semi‑structural formula of glycerol tripalmitate and read the fragment titled „How to name fatty compounds”. Then he writes the name of any fat and its semi‑structural formula on the board. He asks willing students to approach the board and write fat formulas and create their names.

5. The teacher divides the class into groups, distributes sheets of gray paper and colored pens. Students, using abstract, the Internet, textbook and electronic book, create infographics about the occurrence of fats and their biological functions. After completion of activities, the group leaders present the effects of work.

6. 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 straightens the statements of the proteges.

Summary

1. The teacher plays the recording of the abstract. Every now and then he stops it, asking the students to tell in their own words what they have just heard. In this way, students consolidate information learned during the lesson and practice listening comprehension.

2. The teacher asks the students questions:

   • What did you find important and interesting in class?

   • What was easy and what was difficult?

   • How can you use the knowledge and skills you have gained today?

   Willing/selected students summarize the lesson.

Homework

1. Develop a lap book containing issues learned during the lesson and bring your work to the next class.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Structure and biological functions of fats

Esters are compounds that are responsible for lovely fragrance of flowers or fruits. Also fats are classified as esters, although they do not smell lovely. These essential components of our daily diet are naturally found – in meat, fish and oil plants. They are chemically obtained in estrification of glycerol and higher carboxylic acids.

Fats are esters of glycerol and higher carboxylic acids. Fat molecules may contain acid radicals of various fatty acids.

Rules for creating names of fat molecules

A fat molecule is formed in a chemical reaction from glycerol and three fatty acid molecules. Names of fat molecules are derived from common names of alcohol and fatty acids, e.g. glycerol tristearate.

Names consists of two parts or may be more complex, depending on the quantity of various fatty acids that made up given fat molecule.

The first part of the name is derived from the alcohol’s name, namely glycerol and the second is always derived from the name of fatty acid.

If there are three acid radicals of one acid, prefix tri (three) should be added the to acid’s name. It denotes the quantity of fatty acid radicals, for example glycerol tristearate.

If there is more than one type of fatty acid in the fat molecule, we start forming the name from the fatty acid with the shortest carbon chain. Analogously, we add prefix di (two) to the acid’s name from which there are two acid radicals, for example glycerol dioleate palmitate, glycerol dipalmitate stearate, glycerol palmitate oleate stearate.

Which food products contain fats?

In the store you can easily find sunflower, rapeseed, soy, coconut, nut, linseed, grape seed or avocado oil as well as olive oil obtained in various ways. These fats commonly used in the kitchen are found in seeds of plants such as: rapeseed, sunflower, soy, olives, or less frequently nuts, coconut, grapes and avocado. Oils and olive oils are obtained in various processes.

Animal fats are found in meat and milk. Lard is obtained as a result of melting fatty parts of pig, while butter – is churned.

What is the significance of fats for living organisms?

Fats have a very important function in living organisms. Have you wondered why we eat more fats in winter? First of all, fats provide energy to organisms. Fat layer under the skin prevents heat loss and protects internal organs from damage. Fats also transport vitamins soluble in fats: A, D, E and K.

In times of fast foods it is important that we know the rules of rational diet. Obesity is affecting more and more people and is the cause of many diseases. So – what is the matter with fats? Eat them or not to eat them?

As you already know, fats are essential element of our diet. However, it is not advisable to eat too much solid fats, such as lard and butter. Why? Solid fats are mainly esters of saturated fatty acids that increase concentration of cholesterol in blood. It is recommended to provide the body with vegetable fats, which are mostly esters of unsaturated acids named as essential fatty acids (EFA). Have a look at an interactive illustration and check what products contain large amounts of these compounds.

• Fats are esters of glycerol and higher carboxylic acids.

• Fats can be divided – due to their state of aggregation – into solid and liquid ones.

• Fats are classified – due to their origin – into vegetable and animal fats.

• Names of fat molecules are derived from common names of alcohol and fatty acids.

• The first part of the name is from the alcohol’s name, namely glycerol and the second is always derived from the name of fatty acid.

• Fats are essential for proper functioning of the body.

• Fats give us energy and protect internal organs. They also transport vitamins soluble in fats: A, D, E and K.

• Fats are found in seeds of plants such as: rapeseed, sunflower, soy, olives, or less frequently nuts, coconut, grapes and avocado.

• Animal fats are found in animal fat tissues and milk.