Table of contents

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

19. Enzymes

Factors Affecting Enzyme Activity

GOB Chemistry

19. Enzymes

Factors Affecting Enzyme Activity

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4:18 minutes

Problem 58a

Textbook Question

Fresh pineapple contains the enzyme bromelain that hydrolyzes peptide bonds in proteins.
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a. The directions for a gelatin (protein) dessert say not to add fresh pineapple. However, canned pineapple where pineapple is heated to high temperatures can be added. Why?

Verified step by step guidance

Understand the problem: The question is asking why fresh pineapple cannot be added to a gelatin dessert, but canned pineapple can. This involves understanding the role of the enzyme bromelain and how it interacts with proteins in gelatin.

Step 1: Recall that bromelain is an enzyme found in fresh pineapple. Enzymes are biological catalysts that speed up chemical reactions, and bromelain specifically hydrolyzes (breaks down) peptide bonds in proteins.

Step 2: Gelatin is a protein derived from collagen. When gelatin is dissolved in water and cooled, it forms a gel-like structure due to the interaction of its protein molecules. If bromelain is present, it will hydrolyze the peptide bonds in gelatin, breaking down the protein structure and preventing the gel from forming.

Step 3: Canned pineapple is heated during the canning process. High temperatures denature enzymes, which means the bromelain in canned pineapple is inactivated. Denaturation alters the enzyme's structure, rendering it unable to catalyze the hydrolysis of peptide bonds.

Step 4: Since the bromelain in canned pineapple is denatured, it cannot break down the proteins in gelatin. This is why canned pineapple can be added to a gelatin dessert without affecting its ability to set, while fresh pineapple cannot.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Bromelain

Bromelain is a proteolytic enzyme found in fresh pineapple that breaks down protein molecules by hydrolyzing peptide bonds. This enzymatic activity can prevent gelatin from setting properly, as it disrupts the protein structure necessary for the gelatin to solidify.

Gelatin

Gelatin is a protein derived from collagen, commonly used as a gelling agent in food products. It requires a specific temperature and pH to form a stable gel. The presence of bromelain in fresh pineapple can interfere with this process, leading to a failure in achieving the desired texture in gelatin desserts.

Heat Treatment

Canned pineapple undergoes heat treatment during processing, which denatures the bromelain enzyme, rendering it inactive. This means that when canned pineapple is added to gelatin, it does not affect the gelling process, allowing the dessert to set properly without the interference of the enzyme.

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Related Practice

Textbook Question

Pepsin, a peptidase that hydrolyzes proteins, functions in the stomach at an optimum pH of 1.5 to 2.0. How is the rate of a pepsin-catalyzed reaction affected by each of the following conditions?

a. changing the pH to 5.0

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Textbook Question

The following graph shows the activity versus pH curves for pepsin, sucrase, and trypsin. Estimate the optimum pH for each.

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Textbook Question

Refer to the graph in problem 16.45 to determine if the reaction rate in each condition will be at the optimum rate or not.

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a. trypsin, pH 5.0

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Textbook Question

Adults who are lactose intolerant cannot break down the disaccharide in milk products. To help digest dairy food, a product known as Lactaid can be added to milk and the milk then refrigerated for 24 hours.

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b. What might happen to the enzyme if the Lactaid were stored at 55 °C?

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Textbook Question

Fresh pineapple contains the enzyme bromelain that hydrolyzes peptide bonds in proteins.

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b. Fresh pineapple is used in a marinade to tenderize tough meat. Why?

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Textbook Question

Why do enzymes function only under mild conditions?

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Textbook Question

Trypsin, a peptidase that hydrolyzes polypeptides, functions in the small intestine at an optimum pH of 7.7 to 8.0. How is the rate of a trypsin-catalyzed reaction affected by each of the following conditions?

a. changing the pH to 3.0

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Textbook Question

How would the following changes affect enzyme activity for an enzyme whose optimal conditions are normal body temperature and physiological pH?

a. raising the temperature from 37 °C to 60 °C

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