enzymes n.
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  1. Enzymes Enzyme Action Factors Affecting Enzyme Action Enzymes

  2. Enzymes (Chemical Digestion) Remember : • Large particles cannot be absorbed in the small intestine Large particles (e.g. starch) are left in the gut and small particles (e.g. glucose) go through into the blood. INSIDE THE BODY (BLOOD) GUT starch starch starch G G G G G G BUT large particles can be broken down into small particles. This is called DIGESTION starch

  3. Digestive enzymes speed up the process of hydrolysis. Enzymes are biological catalysts. All enzymes are protein in nature. They are ORGANIC CATALYSTS that ___________________ and _______________ chemical reactions without being used up in the process. This means they remain unchanged by the reaction and can be used ______ and _________; A small amount of enzyme can catalyse a _________________ many times, processing a lot of substrate. Enzymes SPEED UP CONTROL OVER OVER REACTION

  4. An enzyme is very specific to the substrate upon which it acts, e.g. The enzyme sucrase will only act upon sucrose to form glucose + fructose (the products). It will not act on any other substrate. • Enzyme reactions are ________________ - they work in both directions. • They work very rapidly. Enzymes are sensitive to high ____________ • Enzymes are sensitive to _________ changes. Enzymes REVERSIBLE Extreme changes in these cause _____________ TEMPERATURE pH DENATURATION

  5. The activation energy which is required to hydrolyse sucrose into its monomers during digestion is indicated in the following graph as X. Enzymes LOWER THE AMOUNT OF ACTIVATION ENERGY needed for a chemical reaction to take place and cause a reaction to occur at a rate fast enough to be ___________________________ without having to add heat. BIOLOGICALLY EFFICIENT Which curve represents the activation energy for this reaction to take place when the required enzyme is added? Provide a reason for your answer.______________________ C – LOWERS AMOUNT OF FREE ENERGY NEEDED AND SPEEDS UP THE REACTION

  6. The shape of enzyme is critical - it must fit exactly into the _____________________ shape of the substrate molecule to cause the reaction. This is why denaturing is so harmful. • This shape on the surface of the enzyme is called the ______________________ • When the substrate and enzyme have locked together, this forms an • ___________________________________________________ • After the reaction, it becomes an _______________________________________. and thereafter they separate and the enzyme moves to the next reaction. LOCK AND KEY HYPOTHESIS COMPLIMENTARY ACTIVE SITE TEMPORARY ENZYME-SUBSTRATE COMPLEX ENZYME-PRODUCT COMPLEX

  7. + + E + S ES complex E + P Lock and Key Model CONDENSATION HYDROLYSIS P S S P

  8. Active site: complimentary to the shape of the substrate P + Q = SUBSTRATEENZYME-SUBSTRATE COMPLEX N = ENZYME M = PRODUCT

  9. Which letter represents the enzyme? Give ONE reason for your choice. _______________________________________________________ • Name two factors that can influence the above reaction. • _______________________________________________________ • _______________________________________________________ • Which one of the following (X, Y or Z) can be represented by the above reaction? • X condensation of two glucose molecules to form sucrose. • Y hydrolysis of sucrose to form glucose and fructose • Z condensation of two different amino acids to form a dipeptide. ________________ • Explain why the other two alternatives are not correct. • _______________________________________________________ N – contains complimentary active site for substrates TEMPERATURE pH Z X – THE SUBSTRATE MOLECULES ARE DIFFERENT AND 2 GLUCOSE WILL BE IDENTICAL Y – THIS IS NOT AN HYDROLYSIS WHERE THE SUBSTRATE IS BROKEN DOWN. IT IS A CONDENSATION

  10. The effect of temperaturechange and enzyme activity:

  11. The particular temperature at which an enzyme acts best is known as its __________________________________________. This temperature is ____________ At temperatures lower than the optimum, the enzyme remains ________________ because they lack _________________. As temperature increases up to the optimum temperature, the enzyme activity ___________________ and then stops as the enzyme starts ________________________. A denatured enzyme loses its shape and hence its specifically shaped _________________________________________. OPTIMUM TEMPERATURE 37,5OC INACTIVE ENERGY INCREASES DENATURING ACTIVE SITE

  12. pH- the amount of H+ ions in a solution. Whatchyall lookin at bra ? 1 2 3 4 5 6 7 8 9 10 11 12 ACID extra H+1 ions (protons) BASE fewer H+1 ions. extra OH+1 ions.

  13. The effect of pH change on enzyme activity: RENNIN RESPIRATORY ENZYME LIPASE

  14. Enzymes work: at their best at a specific pH called the ____________________ pH changes in BOTH directions away from the optimum pH cause the enzyme to become _______________________ - the _______________________ is damaged and can no longer fit the substrate, so it cannot function. OPTIMUM pH DENATURE ACTIVE SITE

  15. Some enzymes can only 'work in the presence of a co-factor. A co-enzyme is an organic, non-protein co-factor that works with the enzyme. "They usually transfer chemical groups from one enzyme reaction to the next, such as carrying hydrogen atoms during cell respiration. Vitamin ______ is a co-enzyme during cell respiration, so it is critical for optimal energy release from food that we take in enough of it, or take supplements during times of stress. CO-ENZMYES B3

  16. The enzyme in a potato Catalase enzyme in potato acts on Hydrogen peroxide H2O2 What’s going on? 1. Catalase enzyme in potato H2 + O2 Hydrogen peroxide Hydrogen gas + Oxygen gas Catalase decomposes hydrogen peroxide into …

  17. 3.1 What is the effect of pepsin on egg-white? (2) 3.2 In which test tube/s will there be a result? (2) 3.3 Give a reason for your answer. (3) 3.4 Explain why there will not be result in the other test tube/s (if there are any). 3.5 What result will be observed? (3) DIGESTS PROTEINS INTO POLYPEPTIDES TT3 HCl (ACID), EGG WHITE (SUBSTRATE) AND PEPSIN (ENZYME) 1 – NO HCl; 2 – NO ENZYME, 4 – ENZYME DENATURED BY BOILING IN TT 3 – PIECES OF EGG WHITE DISAPPEAR AND A CLOUDY SOLUTION RESULTS, AS PROTEIN IS DIGESTED

  18. Name the alcohol produced in the making of wine. _____________________(1) In which starchy product is the same alcohol formed, but lost during the baking process? _______________________ (1) 2 Why is it not possible for natural fermentation to increase the alcohol content of a fermented product to 20% or more? (2) 3 Name the enzyme used in making soft-centred chocolates. ____________ (1) 4 Name three dairy products made using enzymes. _________________________ ___________ (3) QUESTIONS ETHANOL BREAD YEAST DIES WHEN IT REACHES 18% SUCRASE CHEESE, MILK, YOGHURT

  19. 5 Why is rennin/rennet used in cheese making?______________________________ (2) 6 Why is it necessary to denature whey proteins when making yoghurt (1) 7 Which enzymes are used to give jeans a “stone-washed” look? (1) Why is it better to use enzymes than real stones in the above case? Give two reasons. (2) 8 State one specific use of the enzyme ‘isomerase’. _________________________ Why does the use of this enzyme make sense here? (2) 9 What is pectin? 10 Suggest why pectinase can make fruit juice clearer. (2) It coagulates/clots milk IT MAKES THEM CREAMIER CELLULASE ECONOMIC: ENZYMES MORE EASILY SOURCED. FASHION: DOES NOT DAMAGE JEANS CHANGES GLUCOSE INTO FRUCTOSE FRUCTOSE SWEETER, LESS NEEDED, USED IN SLMMNG FOODS POLYSACCHARIDE FOUND IN MIDDLE LAMELLA BREAKS DOWN THE PECTIN AND REMOVES THE PULP

  20. 11.2 Name the enzyme, which was effective in this experiment. (2) ______________________________________________ 11.3 What was found to be the most suitable temperature for the action of this enzyme? (2) _______________________________________________ 11.4 What indicator would you have used to show the presence of starch? (2) ___________________________________________________ 11.5 How long would you expect digestion to have taken place in a similar test conducted at 22,5 0C? (Indicate how you found this on the graph) (2) AMYLASE 35OC IODINE 48 SECONDS

  21. 11.6 Name the end-product of the digestion of the cooked starch. (2) _________________________________________ 11.7 Name TWO other factors affecting enzyme efficiency which could be tested by similar experiments. (2) _______________________________________ _______________________________________ GLUCOSE pH AMOUNT OF SUBSTRATE or AMOUNT OF ENZYME