1.3.1 Function of Food Why do we need food?

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

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

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

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

1.3.2 Chemical Elements Elements in Food

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

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

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

1.3.3 Biomolecular Structures

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

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

Humans are mainly made up of Water!

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

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

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

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

Learning check Name the three elements that make up carbohydrates Carbon Hydrogen Oxygen What is the general formula for a carbohydrate? Cx(H2O)y

1.3.4 Biomolecular Sources and the Components of Food

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

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 Photo Credit fruit image by Edvin selimovic from Fotolia.com These are single sugar molecules simple sugars soluble in water sweet to taste smallest carbohydrate unit Examples: glucose, fructose Found in: fruit

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 Fatty Acid 1 Fatty Acid 2 Fatty Acid 3 Glycerol 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 Fatty Acid 1 Fatty Acid 2 Glycerol Phosphate

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

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

1.3.5 Energy Transfer Reactions Anabolic & Catabolic Or Anabolism & Catabolism

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

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.

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

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.

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

Catabolic Respiration Anabolic Photosynthesis CRAP Catabolic Respiration Anabolic Photosynthesis

Is catabolism the opposite of anabolism? – NO 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.

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

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