1. 1.3.1 Function of Food
Why do we need 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? 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

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

7. 1.3.2 Chemical Elements
Elements in Food

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 trace elements
Fe, Cu, Zn

9. 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

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. 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

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. 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

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

22. Monosaccharides Disaccharides Polysaccharides 3 Types of Carbohydrate22

23. 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. 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

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: Examples Sources
Monosaccharides
Disaccharides
Polysaccharides
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 oils34

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. 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

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 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

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

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. 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

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

51. 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.

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

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

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

55. 1.3.6 Structural Role of Biomolecules

56. 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

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

58. 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

59. 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

60. 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

61. 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

62. 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

63. 1.3.8 Minerals

64. 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.

65. 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

66. 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.

67. 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

68. 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

69. 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

70. 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.

71. Importance of Water to Organisms

72. The three states of water

73. 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.

74. 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.

75. 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

76. 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 …

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

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

79. 1.3.7 Metabolic Role of Biomolecules

80. 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

81. 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

82. 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

83. 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

84. 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

85. 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

86. 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

87. 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

88. 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

89. 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

90. 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

91. 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

92. 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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