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

3 Types of Carbohydrate Monosaccharides Disaccharides Polysaccharides

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

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

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

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

Learning check Name the three types of carbohydrate Monosaccharides Disaccharides Polysaccharides

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.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

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

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