1.3.1 Function of Food Why do we need food?

What you will learn Why we need food Chemical elements in food Biomolecules – carbohydrates, proteins, fats, minerals, vitamins Structure and function of biomolecules Metabolism – anabolism and catabolism Water and its properties

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

Food also supplies: the materials and energy for the processes of: Metabolism and Continuity

Learning check Why do we need food? What is metabolism? 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

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

1.3.2 Chemical Elements Elements in Food

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

Chemical Elements and their Symbols Calcium Ca Nitrogen N Carbon C Oxygen O Chlorine Cl Phosphorus P Copper Cu Potassium K Hydrogen H Sodium Na Iron Fe Sulphur S Magnesium Mg Zinc Zn

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

Types of food (biomolecular structures)

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

Humans are mainly made up of Water! 13

Carbon Hydrogen Oxygen Carbohydrates Carbohydrates contain the elements Carbon Hydrogen Oxygen The general formula for a carbohydrate is Cx(H2O)y There are twice as many hydrogen molecules as oxygen molecules 14

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

A common carbohydrate General formula = Cx(H2O)y When x = y = 6 We fet the formula C6H12O6 What is the name of this monosaccharide carbohydrate? Glucose 16

Another common carbohydrate General formula = Cx(H2O)y When x = 12 and y = 11 We get the formula C12H22O11 What is the name of this disaccharide carbohydrate? Sucrose 17

Carbon Hydrogen Oxygen Learning check Name the three elements that make up carbohydrates Carbon Hydrogen Oxygen What is the general formula for a carbohydrate? Cx(H2O)y 18

Need to know Define Biomolecular Structures State that simple biomolecular units are composed of a combination of elements in different ratios e.g. carbohydrates Cx(H2O)y 19

1.3.4 Biomolecular Sources and the Components of Food

Carbohydrates Carbohydrates contain the elements Hydrogen Oxygen Carbon Hydrogen Oxygen Usually in the ratio of 1C:2H:1O They have twice as many hydrogen molecules as oxygen molecules 21

Monosaccharides Disaccharides Polysaccharides 3 Types of Carbohydrate 22

Monosaccharides These are single sugar molecules simple sugars soluble in water sweet to taste smallest carbohydrate unit Examples: glucose, fructose Found in: fruit 23

Carbon Hydrogen Oxygen Learning check What are the elements that make up all carbohydrates? Carbon Hydrogen Oxygen Can you remember the general formula for a carbohydrate? Cx(H2O)y 24

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 25

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 26

Learning check Name the three types of carbohydrate Monosaccharides Disaccharides Polysaccharides 27

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. 28

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 29

Learning check Give examples and sources of: Examples Sources Monosaccharides Disaccharides Polysaccharides Glucose Fructose fruit Sucrose Lactose Table sugar Milk Starch Cellulose Bread, Pasta, Cereals 30

Types of Lipid Two of the main types of lipids are Triglycerides Phospholipids 31

Triglyceride This is the smallest lipid It is made up of 3 fatty acid molecules and 1 glycerol molecule 32

Phospholipids If one fatty acid of a lipid molecule is replaced by a phosphate group then a phospholipid is formed 33

Sources of Lipids Fat – in and on meat Butter (80% fat) Cooking oils 34

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 35

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 36

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 37

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 38

sulphur, phosphorous or iron 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 39

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 40

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 41

Sources of Vitamins Green leafy vegetables, Eggs, Cheese, Carrots 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 42

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 43

Need to know State that simple bio molecular units are composed of a combination of elements in different ratios e.g. carbohydrates Cx(H2O)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. 44

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 45

1.3.5 Energy Transfer Reactions Anabolic & Catabolic Or Anabolism & Catabolism

Anabolic Reactions This is where energy is used to make large molecules (e.g. C6H12O6) from smaller ones (e.g. CO2 and H2O) using enzymes e.g. Photosynthesis – glucose molecules are formed from carbon dioxide and water using enzymes and the energy from the sun. This is anabolism. Energy is absorbed.

An Anabolic Reaction ENERGY Small molecule Larger molecule Energy being used to join two small molecules to make a larger molecule ENERGY Small molecule Larger molecule

Catabolic Reactions This is where energy is released when large molecules (e.g. C6H12O6) are broken down to form smaller ones (e.g. CO2 and H2O) using enzymes e.g. Respiration – glucose molecules are broken down by enzymes to form carbon dioxide and water and energy is released. This is catabolism. Energy is released.

Learning check Explain Anabolism Energy absorbed. Small  large molecules Give an example of an anabolic reaction Photosynthesis Explain Catabolism Energy released. Large  small molecules Give an example of a catabolic reaction Respiration

Is catabolism the opposite of anabolism? In the examples just given the chemical processes (pathways*) involved in each of them are different, therefore catabolism is not the opposite of anabolism. * e.g. if you travel from A to B – you followed a certain pathway. On the return journey you may come home through C – you followed a different pathway.

Energy Transfer Reactions Respiration – Catabolic reaction C6H12O6 + Oxygen  Energy + CO2 + H2O release Photosynthesis – Anabolic reaction CO2 + H2O + Energy  C6H12O6 + Oxygen absorbed

Learning check Is anabolism the opposite of catabolism ? No Why? Different chemical pathways involved in both.

Need to know Definition of the terms: Anabolic Catabolic Give an example of each

1.3.6 Structural Role of Biomolecules

What does the ‘Structural Role of Biomolecules’ mean? Structure = the way in which something is built e.g. timber structure, steel structure Role = function/job or position Biomolecules = carbohydrates, fats, proteins Structural Role of Biomolecules = the function/job of carbohydrates, fats, proteins in making various parts of living things

Structural role of Carbohydrate Cell Structure Cellulose (polysaccharide) found in plant cell walls Chitin (polysaccharide) found in fungal cell walls and insect exoskeletons

Structural role of Proteins Cell structure Proteins are fibrous (threadlike) in nature. They combine with phospholipids to from cell membranes (lipoproteins) Keratin is the structural protein in skin, hair and nails Myosin is the structural protein in muscle

Learning check What does the ‘Structural Role of Biomolecules’ mean? Structural Role of Biomolecules = the function / job of carbohydrates, fats, proteins in making various parts of living things

Structural role of Lipids Cell Structure Important storage molecules in organisms Heat insulation – e.g. under the skin Waterproof the body Protection around body organs e.g. kidney, heart Phospholipids and lipoproteins are major components in cell membranes Myelin helps transmit messages in nerve cells

Learning check What is the structural role of proteins? Proteins are fibrous (threadlike) in nature. They combine with phospholipids to from cell membranes (lipoproteins) Keratin is the structural protein in skin, hair and nails Myosin is the structural protein in muscle

Need to know Structural Role of Biomolecules State carbohydrates role as cellulose in cell walls State proteins role as fibrous protein e.g. keratin or as myosin State the role of lipids as Phospholipids in cell membranes

1.3.8 Minerals

Minerals What are minerals? They are salts formed from the earth’s rocks. These mineral salts then dissolve in water and are absorbed by plants. Animals get their minerals by eating plants or other animals that contain them. NB Minerals are required by organisms in very small amounts.

Minerals and Plants Plants absorb minerals through their roots. They use: Calcium (Ca) to make cell walls Magnesium (Mg) to make the pigment chlorophyll Nitrates (N) to make proteins Phosphates (P) to make ATP, DNA

Minerals and Animals Animals get their minerals in the food they eat. They use Calcium (Ca) to make bones and teeth Iron (Fe) to make the pigment haemoglobin Sodium (Na) for the regulation of the osmotic balance (water content) of cells and the blood.

Learning check How do plants get their minerals? _________________________________ Plants use: Calcium (Ca) to make ________ Magnesium (Mg) to make _________ _________ Nitrates (N) to make ______ Phosphates (P) to make _________ Plants absorb minerals through their roots cell walls the pigment chlorophyll proteins ATP, DNA

Learning check How do animals get their minerals? ________________ Animals use: Calcium (Ca) to make ____________ Iron (Fe) to make the pigment __________ Sodium (Na) for the regulation of the _____________ (___________) of cells and the blood. In the food they eat bones and teeth haemoglobin osmotic balance water content

Minerals Summary They are required to: Form part of rigid body tissues Calcium in bones and cell walls Form certain pigments Iron is needed to make haemoglobin – the red pigment of blood Magnesium is needed to make chlorophyll – the green pigment in plants Regulate body fluids Sodium balances water content in cells

Need to know Minerals required in small amounts Minerals used in three ways Form part of rigid body structures Form soft body tissues Function in cellular and body fluids State the requirements & use of any 2 minerals in plants. State the requirements & use of any 2 minerals in animals.

Importance of Water to Organisms

The three states of water

Water Cells and body fluids are made up of 70% to 95% Water Water has physical and chemical properties that have important effects on organisms.

Physical properties of water It is slow to heat up and cool down – kept at a fairly steady temperature – helps to keep a constant rate of metabolism. A good absorber of energy. It absorbs a lot of heat as it evaporates, so sweating and transpiration cools animals and plants. This helps to keep temperature steady. Participates in the movement of material in and out of cells. Controls cell shape.

Chemical properties of water It is a universal solvent for transporting substances in blood or in plants The medium for metabolism i.e. chemical reactions take place in it within cells It is a reactant/product in chemical reactions e.g. photosynthesis, respiration and digestion

Learning check What are the physical properties of water? It is slow to heat up and cool down … A good absorber of energy … Movement of material … Cell shape …

Learning check What are the chemical properties of water? Universal solvent … Medium for metabolism … Reactant in chemical reactions …

Need to know Five good reasons why water is important for organisms.

1.3.7 Metabolic Role of Biomolecules

What does the ‘Metabolic Role of Biomolecules’ mean? Metabolic = metabolism = all the chemical reactions in a cell Role = function/job or position/involvement Biomolecules = carbohydrates, fats, proteins Metabolic Role of Biomolecules = the function / job / involvement of carbohydrates, fats, proteins in the chemical reactions in cells making various substances for living things 80

Metabolic Role of Carbohydrates and Lipids These are the primary sources of energy for metabolism – e.g. glucose (carbohydrate) is an immediate source of energy lipids are a long-term energy storage 81

Metabolic Role of Carbohydrates and Lipids They are important in the following processes: Respiration – energy is released when glucose is broken down to form carbon dioxide and water – catabolism Photosynthesis – glucose molecules are made from carbon dioxide and water using the sun’s energy – anabolism 82

Metabolic Role of Proteins All enzymes are proteins and have a folded shape. Enzymes control the chemical reactions in cells. e.g. enzymes control the processes of photosynthesis and respiration Chlorophyll is a protein that traps the sun’s energy during photosynthesis 83

Learning check Give examples of the primary sources of energy for metabolism Glucose & Lipids Name two important metabolic pathways and state whether they are anabolic or catabolic Photosynthesis – anabolic Respiration – catabolic 84

Metabolic Role of Hormones Hormones regulate body functions e.g. the hormone insulin controls the amount of glucose in the blood Oestrogen, progesterone and testosterone are other hormones controlling human sexual development 85

Learning check What is the metabolic role of protein? Enzymes are proteins. Enzymes control the processes of photosynthesis and respiration Chlorophyll is a protein that traps the sun’s energy during photosynthesis 86

Metabolic Role of Vitamins Definition: can you remember it Vitamins are essential organic catalysts of metabolism They are needed in small amounts for the correct functioning of the body They cannot be made by the body They must be in the diet 87

Vitamin C Chemical name: ascorbic acid Solubility: water soluble Function: for building connective tissue i.e. tissue used for attaching organs together or for protection, e.g. skin, blood vessels, bone, tendons, cartilage, ligaments Source: Citrus Fruits, Green vegetables 88

Vitamin D Chemical name: calciferol Solubility: fat soluble Function: needed to absorb calcium from food. Calcium needed for healthy teeth and bone formation and their maintenance Source: Dairy products, fish liver oils, egg yolk, made by skin in sunlight 89

Learning check For the vitamins C & D give the following The chemical name - Solubility - Function - Source in the diet - Vit C Vit D Ascorbic acid Calciferol Water soluble Fat soluble Connective tissue formation Absorb calcium One source One source 90

Vitamin deficiency disorders Lack of Vitamin C causes scurvy Symptoms: soft bleeding gums, bad and loose teeth Lack of Vitamin D causes rickets in young children Symptoms: softening of the bones of the spinal column and bowlegs osteomalacia in adults Symptoms: the bones lose calcium and become weak – common in vegans 91

Need to know State that carbohydrates & lipids act as a primary source of energy State that proteins act as enzymes and are made of amino acids State that hormones (protein) act as regulators of metabolic activity State that vitamin C & D are used for tissue growth, cell production and health maintenance Name disorders associated with deficiency of a water soluble and a fat-soluble vitamin 92

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