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Carbohydrates Carbohydrates contain the elements carbon, hydrogen and oxygen. Come from plants in the form of sugar (glucose) and starch (how plants store glucose). Carbohydrates provide the main source of energy for respiration in living organisms. Sources: • Sugars: honey, jam, molasses, candy, table sugar • Starch: breads, cereals, pasta, potatoes Glucose C6H12O6 C HO C HO C H C HO C H C C C H C OH H C OH C H2OH A glucose molecule as a straight chain O C 5 of the carbon atoms may be arranged in a ring This molecule is often represented simply as a hexagon Other carbohydrates Glucose is a ‘simple’ sugar. Fructose (fruit sugar), maltose and sucrose are more ‘complex’ sugars. 2 molecules of glucose can join together to form a molecule of maltose maltose Starch and cellulose are formed from hundreds of glucose molecules joined to form a long chain one sugar molecule (glucose) carbohydrate molecule The body breaks down long chains of carbohydrates into the smaller sugar molecules. These small sugar molecules are used by the body to release energy and make the body work. PROTEIN Proteins Proteins are made up of carbon, hydrogen and oxygen molecules but with the addition of nitrogen Most proteins are very large molecules, made up of hundreds of amino acids. Enzymes are proteins which carry out specific reactions in cells. What are proteins? Proteins, like carbohydrates, are made of long chains of small molecules. In proteins, these small molecules are not identical. one amino acid protein molecule Proteins are made up of chains of small molecules called amino acids. There are over 20 different kinds of amino acid. Proteins are used by the body for growth and repair. • • • Builds and repairs muscles and cell tissues Helps the body make important substances Regulates body processes & supplies energy Complete proteins: • dairy products, eggs, fish, meat and poultry. Incomplete proteins: • beans, grains and nuts. Lipids Lipids are fats and oils They are made up from glycerol and fatty acids Examples of fatty acids are stearic acid, oleic acid and palmitic acid H2 C O stearic acid H C O oleic acid H2 C O palmitic acid glycerol fatty acids A simple lipid What are fats? Fats are made up of fat molecules, which contain fatty acids and glycerol. fatty acids glycerol fat molecule Fat molecules have to be broken down by the body so that they can be used for energy storage. Fats are also used by the body to keep heat in and to make cell membranes. Function • • • • • Supply energy Carry fat-soluble vitamins Insulate the body Protect organs Provide essential fatty acids Sources Types of Fats • Saturated: dairy products, meats, lard, coconut and palm oils • Unsaturated: fish, nuts, vegetable oils Matching exercise- Connect the statements correctly! Carbon Hydrogen oxygen Protein Carbon Hydrogen oxygen nitrogen Simple sugars e.g. glucose Fat Amino acid Carbon Hydrogen oxygen Carbohydrate e.g. Starch/cellulolse Glycerol and fatty acid 9 Salts and water In addition to proteins, carbohydrates and lipids, cytoplasm contains salts and water Water makes up the bulk of cytoplasm All the chemical reactions in cytoplasm take place in solution, i.e. in water Water itself takes part in many of these chemical reactions Salts of sodium, potassium and calcium and many others play an important part in these reactions Vitamins and minerals boost the immune system, support normal growth and development, and help cells and organs do their jobs. Nutrient Functions Sources Vitamin D Builds strong bones and teeth Vitamin C (ascorbic acid) Helps wounds heal Oranges, grapefruits, tangerines (citrus fruits), cantaloupe, broccoli, Helps fight infection Helps promote healthy gums and tissues, tomatoes and raw cabbage Promote absorption of iron Nutrient Functions Egg yolk; fortified butter, margarine, and milk; the sun Sources Calcium Builds bones and teeth Helps muscles and nerves work Milk, yogurt, cheese, broccoli, salmon, dark veggies, esp. leafy greens Iron Combines with protein to make hemoglobin. Helps cells use oxygen Liver, spinach, raisins and molasses Water Function • • • • Aids digestion and cell growth and maintenance Facilitates chemical reactions Lubricates joints and cells Regulates body temperature Fibre (roughage) • Complex carbohydrates that the body cannot break down. These help clean out the digestive system. Most plants are high in fibre eg fruits, vegetables, whole grains Write each of the following nutrients in the appropriate space below: carbohydrate, fat (lipid), fibre, minerals, protein, vitamins, water. Nutrient Use Fat (Lipids) To store and provide energy. Insulates the body. Protein To grow new tissue, repair damage and provide energy Carbohydrates Water Minerals Vitamins Fibre To provide a supply of energy. The two main forms are sugar and starch To carry things round the body and replace lost water (hydrate) To make healthy blood, bones and other tissues To take part in important chemical reactions in your body To keep the digestive system healthy 10 Enzymes Review Enzymes are special proteins They are present in the cytoplasm of all cells They help to speed up the chemical reactions in the cell There are hundreds of different enzymes but each enzyme speeds up only one kind of reaction For example, glucose and fructose might join up slowly to form sucrose glucose--fructose With the right enzyme present, the reaction happens faster glucose--fructose 24 ENZYME ACTION 1 glucose molecules E 1. A glucose molecule combines with the active site on an enzyme 25 E 2 A region of the active site is still available 26 3 One end of a growing starch molecule combines with the glucose molecule at the active site E part of starch molecule 27 4 The growing starch molecule breaks free from the enzyme which is now free to repeat the reaction E 28 Enzyme action 11 glucose molecules E E 2 E E 3 E E part of starch molecule 4 29 Question 1 The correct formula for glucose is (a) C12H22O11 (b) C5H10O5 (c) C4H8O4 (d) C6H12O6 30 Question 2 Which is the most accurate description of a carbohydrate? A carbohydrate contains (a) carbon and oxygen (b) carbon, oxygen and nitrogen (c) carbon, hydrogen and oxygen (d) carbon and hydrogen 31 Question 3 When two molecules of glucose combine, they form (a) maltose (b) sucrose (c) fructose (d) ribose 32 Question 4 Which is the most accurate description of a protein Proteins contain (a) carbon, hydrogen and oxygen (b) carbon, hydrogen, oxygen and nitrogen (c) carbon, hydrogen and nitrogen (d) carbon, nitrogen and oxygen 33 Question 5 Which statements are correct? Proteins are present in (a) cell membranes (b) cell walls (c) cytoplasm (d) nucleus 34 Question 6 High temperatures damage proteins by (a) decomposing them (b) changing their chemical composition (c) changing their shape (d) making them soluble 35 Question 7 A protein is made up of a series of (a) glucose units (b) fatty acids (c) amino acids (d) carbohydrates 36 Question 8 Lipids are made up of (a) glycerol and amino acids (b) glycerol and fatty acids (c) protein and fatty acids (d) starch and fatty acids 37 Question 9 Enzymes are (a) proteins (b) lipids (c) carbohydrates (d) a combination of these 38 Question 10 An enzyme can (a) change a reaction (b) prevent a reaction (c) slow down a reaction (d) speed up a reaction 39 Question 11 A substrate is a substance which (a) an enzyme acts on (b) is produced by an enzyme reaction (c) is a particular kind of enzyme (d) is any chemical substance in a cell 40 Question 12 An enzyme can (a) combine with different substrates (b) form different kinds of end-product (c) function at temperatures above 90oC (d) speed up a reaction in the cytoplasm 41 Question 13 The part of an enzyme which combines with the substrate is called (a) the reaction centre (b) the active site (c) the action centre (d) the reaction site 42 Question 14 After being exposed to a high temperature an enzyme cannot function because (a) it has been broken down (b) its shape has been changed (c) its composition has been changed (d) it cannot separate from its substrate 43 ANSWER Correct 44 ANSWER Incorrect