Arif Ullah - ITHS

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1 INTERNATIONAL TURKISH HOPE SCHOOL ACADEMIC YEAR CHITTAGONG SENIOR SECTION BIOLOGY HANDOUT BIOLOGICAL MOLECULES (ENZYMES) CLASS 9 Name :... Date:... c) Biological molecules Students will be assessed on their ability to: 2.5 identify the chemical elements present in carbohydrates, proteins and lipids (fats and oils) 2.6 describe the structure of carbohydrates, proteins and lipids as large molecules made up from smaller basic units: starch and glycogen from simple sugar; protein from amino acids; lipid from fatty acids and glycerol 2.7 describe the tests for glucose and starch 2.8 understand the role of enzymes as biological catalysts in metabolic reactions 2.9 understand how the functioning of enzymes can be affected by changes in temperature, including changes due to change in active site 2.10 understand how the functioning of enzymes can be affected by changes in active site caused by changes in ph 2.11 describe experiments to investigate how enzyme activity can be affected by changes in temperature. Human Biology Students will be assessed on their ability to: a) Recall the chemical elements present in carbohydrates, proteins and lipids (fats and oils). b) Understand the structure of carbohydrates, proteins and lipids as large molecules made up from smaller basic units: starch and glycogen from simple sugars; protein from amino acids; lipid from fatty acids and glycerol. c) Describe the tests for glucose, starch, lipid and protein. d) Explain the role of enzymes as biological catalysts in metabolic reactions. e) Explain the functioning of enzymes: how this can be affected by changes in temperature and ph. f) Describe how to carry out simple controlled experiments to illustrate how enzyme activity can be affected by changes in temperature. Teacher in Charge: ARIF ULLAH Page 1

(b) define enzymes as proteins that function as biological catalysts; (c) explain enzyme action in terms of the lock and key hypothesis; (d) investigate and describe the

2 Note: Details about the Carbohydrates, Protein and Fat will be taught in the ANIMAL NUTRITION Topic. Cambridge 3.1 Enzyme action 3.2 Effects of temperature and ph Candidates should be able to: (a) define catalyst as a substance that speeds up a chemical reaction and is not changed by the reaction; (b) define enzymes as proteins that function as biological catalysts; (c) explain enzyme action in terms of the lock and key hypothesis; (d) investigate and describe the effects of temperature and of ph on enzyme activity. Proteins are long chains of Amino Acids joined by Peptide bonds. Each Circle represents a different Amino Acid. Teacher in Charge: ARIF ULLAH Page 2

PROPERTIES OF ENZYMES * All enzymes are proteins (but all proteins are not enzymes). * They act as biological catalysts, ie they speed up the work without getting used up.

Protease breaks down only Proteins into Amino Acids. Lipase breaks down only Fats into Fatty Acids and Glycerol. * All enzymes have Active Sites where substrates fit.

3 PROPERTIES OF ENZYMES * All enzymes are proteins (but all proteins are not enzymes). * They act as biological catalysts, ie they speed up the work without getting used up. * They act specific in their actions, ie one enzyme can control only one type of reaction. e.g.- Carbohydrase breaks down only Carbohydrates into Glucose. Protease breaks down only Proteins into Amino Acids. Lipase breaks down only Fats into Fatty Acids and Glycerol. * All enzymes have Active Sites where substrates fit. * They are affected by temperature and ph. * They work best at a particular temperature and ph, known as Optimum Condition. WORKING OF ENZYMES Enzyme+substrate forms Enzyme-Substrate complex->enzyme+products Lock and key hypothesis * All enzymes have Active Sites where substrate fit, like a key having a particular shape or ridges. * A specific keyis required for a particular lock. Similarly, a specific enzyme can control a specific reaction. * As key fits into a lock, a substrate also fits into an enzyme. Therefore, key = Substrate & lock = Enzyme. * If the shape of the key changes, the lock does not open. Similarly, if the enzymes get denatured, the shape of the Active Site changes and the reaction stops. Teacher in Charge: ARIF ULLAH Page 3

Catalysts speed up a reaction without getting used up. Enzymes are biological catalysts as they are made up in our body, therefore, an enzyme can be used for a long time.

4 Catalysts speed up a reaction without getting used up. Enzymes are biological catalysts as they are made up in our body, therefore, an enzyme can be used for a long time. Example of catalyst: The nail acts like a catalyst here. In the first reaction, due to the active site (pointed region) the substrate (balloon) bursts and the enzyme (nail) remains unchanged. In the second reaction, due to the change in active site (the blunt side) no change occurs. This is a catabolic reaction as substrate is broken (balloon is broken down into many products). Teacher in Charge: ARIF ULLAH Page 4

5 FACTORS AFFECTING ENZYME ACTIVITY Teacher in Charge: ARIF ULLAH Page 5

EFFECT OF TEMPERATURE ON ph In an enzyme control reaction, * The reaction increases with an increase in temperature. * The reaction becomes double for every 10 0 C rise in temperature.

* The reaction becomes nil around 50 0 C as the enzymes get destroyed.

Thus, more products are formed. Therefore, the reaction becomes double. * At Optimum temperature, the rate of reaction is highest. All the enzymes get used up during the Optimum temperature.

6 EFFECT OF TEMPERATURE ON ph In an enzyme control reaction, * The reaction increases with an increase in temperature. * The reaction becomes double for every 10 0 C rise in temperature. * It reaches the highest point, known as Optimum Temperature, where enzymes work best. * After 40 0 C, the reaction decreases and falls sharply, as the enzymes get denatured. * The reaction becomes nil around 50 0 C as the enzymes get destroyed. EXPLANATION OF TEMPERATURE AFFECTING ENZYME ACTION * With an increase in temperature, the molecules get kinetic energy and collide with one another. Hence the enzyme-substrate complex are formed. Thus, more products are formed. Therefore, the reaction becomes double. * At Optimum temperature, the rate of reaction is highest. All the enzymes get used up during the Optimum temperature. Hence, no more products are formed. * Due to high temperature, the enzymes get denatured. The Active Site changes and the substrate cannot fix into it, to form enzyme-substrate complex. Hence, no products can be formed. Therefore, the reaction becomes nil. EFFECT OF ph ON AN ENZYME ACTIVITY ph= The measure of Hydrogen ions present in a substance. It is measured on a scale of 1 to 14. * 7 is known as Neutral. * Less than 7 is known as Acidic. * More than 7 is known as Alkaline. There are usually three ph types of enzymes. a) Carbohydrase--> 7 Neutral) b) Protease--> 2 or 3 ( Acidic) c) Lipace--> 8 or 9 (Alkaline) Teacher in Charge: ARIF ULLAH Page 6

* In an enzyme- controlled reaction, the enzymes work out best at an optimum ph (usually 7). An increase or decrease in ph values, the activity decreases. At lower ph, enzymes are inactive.

7 * In an enzyme- controlled reaction, the enzymes work out best at an optimum ph (usually 7). An increase or decrease in ph values, the activity decreases. At lower ph, enzymes are inactive. At higher ph, the enzymes get denatured. THREE MAIN CLASSES OF ENZYMES AND THEIR OPTIMUM ph COMPLEX ENZYME SIMPLE OPTIMUM ph Carbohydrates Carbohydrase Glucose 7 Proteins Protease Amino Acids 3 Fats Lipase Fatty acids 9 BIOLOGICAL WASHING POWDER * A biological detergent is a laundry detergent that contains enzymes harvested from micro-organisms such as bacteria adapted to live in hot springs Some detergents like Tide, Wheel and Surf Excel contain biological enzymes to remove stains. Stains are the dried remainings of curry, oil etc. Detergents contain the three type of enzymes, which can digest carbohydrates, proteins and fats from the stains. Therefore, the clothes are soaked in warm water mixed with the detergent. The warm water provides the optimum temperature for enzymes to work out best (37 0 C). We shouldn't use boiling water for washing clothes as high temperature denatures the enzymes present in the detergents. Teacher in Charge: ARIF ULLAH Page 7

FOOD TEST TEST FOR STARCH (IODINE TEST) Add few drops of iodine solution (kt 2 ) to the food sample. If the colour changes to blue-black, starch is present.

8 FOOD TEST TEST FOR STARCH (IODINE TEST) Add few drops of iodine solution (kt 2 ) to the food sample. If the colour changes to blue-black, starch is present. If the colour remains brown/yellow, starch is absent. TEST FOR GLUCOSE (REDUCING SUGAR)- BENEDICT'S TEST Add equal amount of Benedict's solution to the food sample (crush the food sample and add water if the food sample is solid). Heat the solution in a water bath. If the red precipitate is seen, glucose is present. If the colour remains blue, glucose is absent. TEST FOR PROTEINS (BUIRET'S TEST) Add equal amount of Buiret I and II solution to the food sample. If the the colour remains blue, protein is absent. If the colour changes to purple, protein is present. TEST FOR FATS a) Emulsion/Ethanol test. Add the food sample to Alcohol/Ethanol, then add water. If the colour changes to clear, fat is absent. If the colour is milky, fat is present. b) Grease-spot test Rub the food sample on a white paper. If a translucent/semi transparent spot is formed, fat is present. If clear, no fat is present. Teacher in Charge: ARIF ULLAH Page 8

G.T. College G10 Term One Biology Form Test 2

G.T. College G10 Term One Biology Form Test 2 G.T. College 2018 19 G10 Term One Biology Form Test 2 Total marks: 40 marks Time allowed: 35 minutes Date: Name: Class: ( ) Section A: Multiple choice questions (10 marks@ 1 mark each) 1. Given a solution