Enzymes
I. What is an enzyme?
Thousands of chemical reactions take place in our cells. We need these reactions to occur rapidly in order to keep us alive. Enzymes are the chemicals (biological catalysts) within our cells that speed up these reactions. II. Types of enzymes
1. BREAKERS
These enzymes speed up the reaction that breaks down large molecules into smaller ones. This is important in food digestion so that we can break down food molecules into their various components to enable us to use them. 2. BUILDERS
Some reactions require small molecules to be joined together to make larger ones. Builder enzymes speed up these reactions and build important molecules inside our cells. 1 III. How an enzyme works
Enzymes are proteins and are made up of long chains of amino acids. They are folded in a specific way to produce a special shape called the active site. Specific molecules (substrates) fit into the active site and the reaction takes place. Diagram cited from: https://www.xtremepapers.com IV. Enzymes have five important properties
1. Enzymes are all proteins; made up of amino acids. 2. Each enzyme controls a specific reaction; enzymes are specific so in general, each enzyme is only able to work on a specific substrate, which has to fit into its active site. If the enzyme denatures, its active site loses its shape. 3. They can be used again and again; enzymes work on a substrate and once that is done they will move on to the next bit of substrate until all is used up. 4. They are affected by temperature; changing the temperature changes the rate of an enzyme-­‐catalysed reaction. The higher the temperature, the faster the reaction – to a certain level. Once the temperature gets too high, the enzyme will denature. Optimum temperature is around 37 degrees. 2 5. They are affected by pH; if the pH is too low or high the enzyme will denature and stop working. Optimum pH in general is neutral pH 7 however some specific enzymes will be different, for example the pepsin enzyme in the stomach needs acidic conditions of pH 2. V. Enzymes and digestion
Digestive enzymes are builders. They break down big molecules into smaller ones. Sugars, amino acids, glycerol and fatty acids are small molecules that easily pass through the walls of the digestive system. Starch, proteins and fats are too big to pass through the walls of the digestive system and require digestive enzymes to break them down into smaller parts. Amylase enzyme breaks starch down into sugars and is produced in the salivary glands, pancreas and the small intestine. Protease enzyme breaks proteins down into amino acids and is produced in the stomach (pepsin), pancreas and the small intestine. Lipase enzyme breaks lipids down into glycerol and fatty acids and is produced in the pancreas and small intestine. Diagram cited from: http://www.abpischools.org.uk/ 3 VI. Enzymes and respiration
Enzymes control many chemical reactions inside cells, including those in respiration. These reactions are very important as respiration releases energy, which the cells need for just about everything. Respiration is the breakdown of glucose and it occurs in every cell in our body and in plants too. All living things respire; it is how they release energy from their food. Diagram cited from: http://study.com/academy VII. Enzymes in the home
Enzymes are used in the home in biological detergents to remove stains such as grass, sweat and food from clothing. These biological detergents contain lipases and proteins, which break down both the fats and proteins in stains giving you a cleaner wash. Biological detergents need to be used at lower temperatures as they work best at lower temperatures and will be denatured if the water is too hot. VIII. Enzymes in the industry
Enzymes, such as proteases, are used to make baby foods. They predigest some of the protein in the food, as at first, babies are not very good at digesting protein. This helps the baby to absorb the amino acids they need from the food. 4 Carbohydrases are used to convert starch into sugar (glucose) syrup, which we use large amounts of in food production. Starch is made by plants; such as corn. It is very cheap. Using enzymes to convert plant starch into sugar provides a cheap source of sweetness for food manufacturers. IX. Advantages and disadvantages of using
enzymes
ADVANTAGES DISADVANTAGES Energy saving Denature at high temperatures Time saving Require a specific pH to function Cost saving Can be expensive to produce Eco friendly Specific 5 MCQ
1. The best description of a denatured enzyme is one that: a) Will work on various substrates b) Will only work on one substrate c) Has a disfigured active site d) Catalyses a reaction 2. All enzymes are: a) Carbohydrates b) Sugars c) Proteins d) Fats 3. What is the component part of enzymes? a) Glucose b) Starch c) Amino acids d) Lipids 4. What is the area of an enzyme that the substrate fits into? a) Active site b) Activation site c) Activity site d) Initiation site 6 5. Which of the following does not affect the initial rate of an enzyme controlled reaction? a) A change in pH b) A decrease in the concentration of substrate c) An increase in temperature d) An increase in the duration of the reaction 6. Amylase is produced in the: a) Stomach b) Salivary glands c) Large intestine d) Liver 7. Protease is not produced in the: a) Stomach b) Pancreas c) Small intestine d) Gall bladder 8. Biological washing powders contain enzymes. This means the powder: a) Allows washing to occur effectively at higher temperatures b) Allows washing to occur effectively at lower temperatures c) Allows washing to occur equally effectively as with non-­‐biological powders d) Can only be used to remove food stains 9. What is another name for enzymes? a) Biological catalysts b) Mutations 7 c) Stem cells d) Active sites 10. What is the name of the mechanism of enzyme activity? a) Knife and fork b) Hammer and nail c) Lock and key d) Substrate and active site 8