4318936
Description
Flashcards by Ella-mentary, updated more than 1 year ago
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Created by Ella-mentary
over 8 years ago
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| Question | Answer |
| Enzymes | Large molecules folded to form a 3-dimensional globular structure that act as catalysts. |
| Active site | A specifically shaped site for a substrate to fit into. |
| Factors affecting enzyme action | Substrate concentration pH Temperature |
| Substrate concentration | As [substrate] increases, more collisions occur with the enzymes and so more reactions occur - until all active sites are occupied by substrate. |
| pH | Changing the pH affects the bonds which hold the 3D shape of the enzyme together. If the shape of the active site changes, the reaction rate is reduced. |
| Role of molecular motion in enzyme catalysis | Reactions happen when substrate and enzyme molecules collide with one another. |
| Temperature | Increasing temperature increases the molecular movement, so the molecules in the solution collide with enzymes more often, so more reactions occur. However, high temperatures can denature enzymes. |
| Denaturation | The irreversible, structural change in the active site of an enzyme that makes it unable to catalyse, as the substrate no longer fits the active site. |
| Practical use of enzymes | Production of lactose-free milk by hydrolysis of lactose. |
| Lactose intolerance | Some adults are intolerant to lactose, as the gene producing lactase gets switched off with age. Lactose is a disaccharide and cannot be absorbed in the gut so it is fermented by bacteria in the large intestine resulting in nausea, abdominal pain and diarrhea. |
| Lactose-free milk production | Milk is treated with lactase; this breaks down lactose to the monosaccharides glucose and galactose, which are easily absorbed by the gut. |
| Practical production of lactose-free milk | The lactase is immobilized and the milk is passed over it; this prevents the lactase from being in the product and is more economical, as it can then be reused. |
| Metabolic pathways | Consist of chains and cycles of enzyme-catalysed reactions. |
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