1.3.1 Function of Food

1. Why do we need food? 1.3.1 Function of Food

2. 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

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

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

5. 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

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

7. Elements in Food 1.3.2 Chemical Elements

8. 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 traceelements Fe, Cu, Zn

9. Chemical Elements and their Symbols

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

11. Types of food (biomolecular structures)

12. 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

13. Humans are mainly made up of Water! 13

14. 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

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

16. 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

17. 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

18. 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

19. 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

20. 1.3.4 Biomolecular Sources and the Components of Food

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 21

22. 3 Types of Carbohydrate Monosaccharides Disaccharides Polysaccharides 22

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

24. 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

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 25

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 26

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

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. 28

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 29

30. Learning check Give examples and sources of: Glucose Fructose fruit Sucrose Lactose Table sugar Milk Starch Cellulose Bread, Pasta, Cereals 30

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

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

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

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

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 35

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 36

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 37

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 38

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 39

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 40

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 41

42. Sources of Vitamins 42

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 43

44. 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

45. 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

46. Anabolic & Catabolic Or Anabolism & Catabolism 1.3.5 Energy Transfer Reactions

47. 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.

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

49. 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.

50. 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