2.5 - Enzymes - Key terms

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Flashcards by Ella-mentary, updated more than 1 year ago
Ella-mentary
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International Baccalaureate Biology (2 - Molecular Biology) Flashcards on 2.5 - Enzymes - Key terms, created by Ella-mentary on 01/17/2016.

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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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