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Enzymes

AQA AS-level BiologyTopic 2 of 1417 lessons

Revision notes for Enzymes in AQA Biology (7401). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

  1. EnzymesEnzymes are biological catalysts.
  2. Enzyme StructureEnzymes have a specific 3D shape (tertiary structure) as a result of their amino-acid sequence.
  3. Induced-fit ModelThe proximity of the substrate leads to a change in the shape of the enzyme which moulds itself around the substrate.
  4. Lock and Key ModelThe previous model of enzyme action was that the substrate fits precisely into the active site like a key fits in a lock.
  5. Measuring Enzyme-Catalysed ReactionsFactors affecting the activity of an enzyme will be factors that influence the ability of the substrate to bind to the active site and form…
  6. Measuring the Rate of ReactionEnzyme activity is the rate of enzyme reaction, generally expressed as units of substrate converted (or product formed) per unit time.
  7. Effect of Temperature on Enzyme ActionAs the temperature is increased the kinetic energy of the molecules increases and the molecules move faster and collide more often and with more…
  8. Effect of pH on Enzyme ActionThe tertiary structure of the active site of the enzyme is determined by hydrogen and ionic bonds between -NH2 and -COOH groups and bonding and…
  9. Effect of Enzyme ConcentrationEnzymes are biological catalysts.
  10. Effect of Substrate ConcentrationAt low substrate concentration not all the active sites of the enzymes are filled as there are relatively few molecules of substrate.
  11. Different EnzymesAs with many chemical reactions, the rate of an enzyme-catalysed reaction increases as the temperature increases.
  12. Competitive InhibitorsInhibitors are substances that interfere with the function of enzymes either directly or indirectly.
  13. Non-Competitive InhibitorsNon-competitive inhibitors bind to a site which is not the active site.
  14. End-Product InhibitionEnd-product inhibition is used to control the level of the final product in a metabolic pathway.
  15. Exam Style Question 1The enzyme maltase catalyses the hydrolysis of maltose to glucose.
  16. Exam Style Question 2A student investigated the effect of temperature on the activity of the enzyme amylase.
  17. Exam-Style Question 3A scientist investigated the effect of an inhibitor on an enzyme-controlled reaction.

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