1.3.1 Function of Food Why do we need food?

Need to know The Function of Food Three reasons for requiring food 2

Food is needed for: 1.Energy 2.Growth of new cells and Repair of existing cells, tissues, organs, etc. 3

Food also supplies: the materials and energy for the processes of: 1.Metabolism and 2.Continuity 4

Learning check Why do we need food? Energy Growth of new cells and Repair of existing cells, tissues, organs, etc. What is metabolism? Metabolism is the chemical reactions that occur in the cells of living organisms What is continuity? Continuity of life is the ability of an organism to exist from generation to the next 5

1.3.2 Chemical Elements Elements in Food

Need to know Chemical elements Six common elements in food Five elements in dissolved salts Three trace elements 7

What is Food made up of? Food is made up of: Six chemical elements C, H, O, N, P, S Salts of Na, Mg, Cl, K, Ca Three trace elements Fe, Cu, Zn 8

Chemical Elements and their Symbols CalciumCaNitrogenN CarbonCOxygenO ChlorineClPhosphorusP CopperCuPotassiumK HydrogenHSodiumNa IronFeSulphurS MagnesiumMgZincZn 9

1.3.3 Biomolecular Structures

Need to know Define Biomolecular Structures State that simple biomolecular units are composed of a combination of elements in different ratios e.g. carbohydrates C x (H 2 O) y 11

Types of Food The elements combine in different ratios to form different food components (biomolecular units) Food is made up of six different components WaterProteins Lipids Carbohydrates Vitamins Minerals 12

Humans are mainly made up of Water! 13

Carbohydrates Carbohydrates contain the elements CarbonHydrogenOxygen The general formula for a carbohydrate is C x (H 2 O) y There are twice as many hydrogen molecules as oxygen molecules 14

Learning check What are the six different food components? WaterProteins Lipids Carbohydrates Vitamins Minerals 15

A common carbohydrate General formula = C x (H 2 O) y When x = y = 6 We fet the formula C 6 H 12 O 6 What is the name of this monosaccharide carbohydrate? Glucose 16

Another common carbohydrate General formula = C x (H 2 O) y When x = 12 and y = 11 We get the formula C 12 H 22 O 11 What is the name of this disaccharide carbohydrate? Sucrose 17

Learning check Name the three elements that make up carbohydrates CarbonHydrogenOxygen What is the general formula for a carbohydrate? C x (H 2 O) y 18

1.3.4 Biomolecular Sources and the Components of Food

Need to know State that simple bio molecular units are composed of a combination of elements in different ratios e.g. carbohydrates C x (H 2 O) y Name the element components, bio molecular components and sources of: carbohydrates, lipids and proteins. State that carbohydrates are composed of indivisible units and give examples of these e.g. –Monosaccharides – glucose; –Disaccharides – maltose; & –Polysaccharides – starch/cellulose. 20

Need to know What is a vitamin? Name one water soluble vitamin. Name one water in-soluble vitamin (fat- soluble) List the sources of these vitamins 21

Carbohydrates Carbohydrates contain the elements Carbon Hydrogen Oxygen Usually in the ratio of 1C:2H:1O They have twice as many hydrogen molecules as oxygen molecules 22

3 Types of Carbohydrate Monosaccharides Disaccharides Polysaccharides 23

Monosaccharides These are single sugar molecules simple sugars soluble in water sweet to taste smallest carbohydrate unit Examples:glucose, fructose Found in:fruit 24 O CC C C C C

Learning check What are the elements that make up all carbohydrates? Carbon Hydrogen Oxygen Can you remember the general formula for a carbohydrate? C x (H 2 O) y 25

Disaccharides These are two monosaccharide sugar units joined together – known as double sugar molecules soluble in water sweet to taste Examples: sucrose, lactose, maltose Found in:table sugar, milk 26

Polysaccharides These are Many monosaccharide sugar molecules joined together Not soluble in water Do not taste sweet Example:starch, cellulose Found in:bread, pasta, cereals 27

Learning check Name the three types of carbohydrate Monosaccharides Disaccharides Polysaccharides 28

Lipids Lipids are a diverse group of substances which include fats (solid at room temp.) oils (liquid at room temp.) steroids which include cholesterol and some of the sex hormones waxes which cover insect bodies and plant leaves. 29

Structure of Lipids They are made up of the elements carbon hydrogen oxygen But not have the same ratios as carbohydrates. They are made up of two main types of molecules Fatty acids and Glycerol 30

Learning check Give examples and sources of: 31 ExamplesSources Monosaccharides Disaccharides Polysaccharides Glucose Fructose fruit Sucrose Lactose Table sugar Milk Starch Cellulose Bread, Pasta, Cereals

Types of Lipid Two of the main types of lipids are Triglycerides Phospholipids 32

Triglyceride It is made up of 3 fatty acid molecules and 1 glycerol molecule 33 This is the smallest lipid

Phospholipids If one fatty acid of a lipid molecule is replaced by a phosphate group then a phospholipid is formed 34

Sources of Lipids Fat – in and on meat Butter (80% fat) Cooking oils 35

Learning check The two main types of molecules that make up lipids are: Fatty acids and Glycerol The two main types of lipids are: Triglycerides Phospholipids 36

Proteins Proteins contain the elements Carbon Hydrogen Oxygen Nitrogen Some may also contain sulphur, phosphorous or iron Proteins are found in lean meat, fish, pulses, soya and eggs 37

Structure of Proteins Proteins are made up of long chains of amino acids There are 20 common and several rare amino acids found in proteins More amino acids are found in cells and tissues but are not in proteins Amino acids are joined together by peptide bonds This results in the formation of polypeptide chains 38

Amino Acids All amino acids contain four distinct chemical groups connected to a central carbon atom: a single hydrogen atom an amino group a carboxyl group a side chain 39

Learning check Proteins contain the elements Carbon Hydrogen Oxygen Nitrogen Sometimes they contain sulphur, phosphorous or iron Proteins are made up of long chains of amino acids 40

Vitamins Vitamins are essential organic catalysts of metabolism Needed in small amounts, cannot be produced in the body Must be supplied continuously and in sufficient quantities Differ from each other chemically 41

Vitamins We need Vitamins A, B, C, D, E and K in our diets to keep us healthy Vitamins can be water soluble or fat soluble Vitamins B and C are water soluble Vitamins A, D, E and K are fat soluble 42

Sources of Vitamins VitaminSource A Green leafy vegetables, Eggs, Cheese, Carrots B Lean Meat, Cereals, Nuts C Citrus Fruits, Green vegetables, Turnips D Milk and Milk products, Sunlight E Vegetable oils, fish, nuts K Green leafy vegetables 43

Learning check What is a vitamin? A vitamin is an essential organic catalyst of metabolism What vitamins dissolve in water? B & C What vitamins are fat-soluble? A, D, E and K 44

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