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Boardworks GCSE Additional Science: Biology

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Presentation on theme: "Boardworks GCSE Additional Science: Biology"— Presentation transcript:

1 Boardworks GCSE Additional Science: Biology
Digestive Enzymes Digestive Enzymes

2 Boardworks GCSE Additional Science: Biology
Digestive Enzymes

3 Boardworks GCSE Additional Science: Biology
Enzymes and cells Boardworks GCSE Additional Science: Biology Digestive Enzymes Enzymes catalyze the thousands of reactions that need to take place in order to maintain life. What are some of these reactions? digestion respiration photosynthesis (plants and some bacteria) protein synthesis.

4 What are digestive enzymes?
Boardworks GCSE Additional Science: Biology Digestive Enzymes Not all enzymes work inside cells. In what process do enzymes work outside cells? Digestive enzymes are produced by specialized cells in the pancreas and digestive tract. These enzymes pass out of the cells and into the stomach and small intestine. Here the enzymes help to break down large food molecules into smaller molecules that are more easily absorbed.

5 Boardworks GCSE Additional Science: Biology
Enzymes of digestion Boardworks GCSE Additional Science: Biology Digestive Enzymes Teacher notes This activity could be used to check students’ understanding of chemical digestion.

6 Digestion in the stomach
Boardworks GCSE Additional Science: Biology Digestive Enzymes When food enters the stomach it stimulates the secretion of hydrochloric (HCl) acid from the stomach wall. Hydrochloric acid increases the acidity of the stomach to about pH2. This is the optimum pH for stomach enzymes. oesophagus mucus cells gastric gland parietal cells (acid-producing) duodenum

7 Digestion in the small intestine
Boardworks GCSE Additional Science: Biology Digestive Enzymes Digestive enzymes found in the small intestine are damaged by a strongly acidic pH. How does the body avoid this problem? The liver produces bile (an alkali), which is stored in the gall bladder and released into the small intestine. hepatic duct Bile neutralizes the acidic contents coming from the stomach, creating the alkaline environment that the intestinal enzymes need to work. gall bladder The information on this slide is higher tier for Edexcel GCSE Additional Science. pancreas bile duct duodenum

8 Boardworks GCSE Additional Science: Biology
Digestive Enzymes

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Enzymes in the home Boardworks GCSE Additional Science: Biology Digestive Enzymes How many items are made using enzymes? Teacher notes This illustration contains several discussion points relating to items made using enzymes, including: Baby food: proteases such as trypsin are used to predigest the protein in baby foods. Baking (bread): fungal enzymes are used to catalyze the breakdown of starch into sugar. The enzymes also produce carbon dioxide gas, which makes the dough rise. Biological detergent (washing powder): proteases, amylases and lipases are used to remove protein, starch and oily stains from clothes. Brewing (beer): proteases in barley are released as it is fermented during beer production. The enzymes break down starch, carbohydrates and proteins, and clarify stored beers. Confectionary (chocolates): enzymes are used to make soft-centred chocolates. Dairy products (cheese): rennet (an enzyme from calves’ stomachs) is used to coagulate milk during cheese production, separating the curd (solids) from the whey (liquid). Lipases are used to enhance the flavour and ripening of blue cheeses, and lactases are used to break down lactose into glucose and galactose. Fruit juice: enzymes that act on cellulose reduce the cloudiness of fruit juices. Paper (penicillin box): proteases and cellulases are used to soften and smooth pulped fibres during paper manufacture Photography: proteases are used to dissolve gelatin from waste film, allowing its silver content to be recovered and recycled. Rubber (place mat in high chair): catalase is used to convert latex into foam rubber.

10 Boardworks GCSE Additional Science: Biology
Bread-making Boardworks GCSE Additional Science: Biology Digestive Enzymes Teacher notes This three-stage animation shows how enzymes are used in bread-making. Suitable prompts could include: What happens to the amylase and invertase during the baking process? What is the name of the gas that the yeast produce during fermentation?

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Making alcohol Boardworks GCSE Additional Science: Biology Digestive Enzymes Teacher notes This activity could be used as a precursor to a wider discussion on drugs use and abuse. See the Boardworks GCSE Science Biology Drug Use and Abuse presentation for more information on alcohol.

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Confectionery Boardworks GCSE Additional Science: Biology Digestive Enzymes A type of enzyme called isomerase converts the sugar glucose into fructose, another type of sugar. Fructose is sweeter than glucose, so a smaller amount is needed. This makes fructose syrup a useful ingredient in slimming foods. Invertase is used to create soft-centered chocolates. The centre initially contains sucrose (cane sugar) and is hard. The invertase breaks down the sucrose into the simpler sugars glucose and sucrose, making the centre soft and runny.

13 How do enzymes help to clean clothes?
Boardworks GCSE Additional Science: Biology Digestive Enzymes Biological washing powders and liquids contain enzymes that help remove stains. The enzymes are coated with a special wax that melts in the wash, releasing the enzymes. Once the stains have been broken down, they are easier for the detergent to remove. Proteases break down proteins in stains such as grass, blood and sweat. Lipases break down stains containing fat and oil. Carbohydrases break down carbohydrate-based stains, such as starch.

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Producing enzymes Boardworks GCSE Additional Science: Biology Digestive Enzymes Many of the enzymes used in the home and in industry are naturally produced by micro-organisms such as bacteria and yeast. These enzymes are very useful in manufacturing processes because they catalyze reactions in a very predictable way and can replace harmful chemical supplements. Bacteria and yeast can be manipulated and/or genetically engineered to produce these enzymes on an industrial scale. This process is called fermentation. bacteria

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Fermentation Boardworks GCSE Additional Science: Biology Digestive Enzymes

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Are enzymes the future? Boardworks GCSE Additional Science: Biology Digestive Enzymes Teacher notes Appropriately coloured voting cards could be used with this classification activity to increase class participation.

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Digestive Enzymes The worksheet ‘Enzymes’ accompanies this presentation.

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Glossary Boardworks GCSE Additional Science: Biology Digestive Enzymes Teacher notes catalyst – A substance that changes the rate of a reaction without being used up. denatured – The state of an enzyme when it has been irreversibly damaged and has changed shape. enzyme – A biological catalyst. fermentation – The conversion of sugar to ethanol and carbon dioxide by enzymes in yeast. optimum – The temperature and pH at which an enzyme-catalyzed reaction proceeds at the fastest rate.

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Match the reactant Boardworks GCSE Additional Science: Biology Digestive Enzymes Teacher notes This matching activity could be used as a plenary or revision exercise on enzymes. Students could be asked to complete the questions in their books and the activity could be concluded by the completion on the IWB.

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Multiple-choice quiz Boardworks GCSE Additional Science: Biology Digestive Enzymes Teacher notes This multiple-choice quiz could be used as a plenary activity to assess students’ understanding of digestive enzymes. The questions can be skipped through without answering by pressing the forward arrow. Students could be asked to complete the questions in their books and the activity could be concluded by the completion on the IWB.


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