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Published byOscar Allen Modified over 5 years ago
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1.3.4 Biomolecular Sources and the Components of Food
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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
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3 Types of Carbohydrate Monosaccharides Disaccharides Polysaccharides
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Monosaccharides These are single sugar molecules simple sugars
soluble in water sweet to taste smallest carbohydrate unit Examples: glucose, fructose Found in: fruit
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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
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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
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Lipids Lipids are a diverse group of substances which include
fats (solid at room temp.) oils (liquid at room temp.)
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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
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Types of Lipid Two of the main types of lipids are Triglycerides
Phospholipids
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Triglyceride This is the smallest lipid It is made up of
3 fatty acid molecules and 1 glycerol molecule
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Phospholipids If one fatty acid of a lipid molecule is replaced by a phosphate group then a phospholipid is formed
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Sources of Lipids Fat – in and on meat Butter (80% fat) Cooking oils
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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
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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 Amino acids are joined together by peptide bonds This results in the formation of polypeptide chains
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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
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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
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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
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1.3.6 Structural Role of Biomolecules
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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
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Structural role of Carbohydrate
Cell Structure Cellulose (polysaccharide) found in plant cell walls Chitin (polysaccharide) found in fungal cell walls and insect exoskeletons
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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
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Structural role of Lipids
Cell Structure Important storage molecules in organisms Heat insulation – e.g. under the skin Protection around body organs e.g. kidney, heart Phospholipids and lipoproteins are major components in cell membranes
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