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Enzymes

Enzymes . Introduction to Enzymes . Chemical reactions all occur at different rates Some are very quick and some are extremely slow . Introduction to Enzymes. We can speed up some chemical reactions by: 1. increasing the temperature

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Enzymes

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  1. Enzymes

  2. Introduction to Enzymes • Chemical reactions all occur at different rates • Some are very quick and some are extremely slow

  3. Introduction to Enzymes • We can speed up some chemical reactions by: 1. increasing the temperature 2. adding a catalyst • Since it is not always appropriate increasing the temperature of a living organism, biological catalysts called ENZYMES are used to increase the rate of reaction.

  4. Enzymes • An enzyme is a substance which can speed up a reaction without itself being altered. • There are 3 important points that are true for all enzymes and catalysts: • When an enzyme is present, the reaction requires less energy to start. • When an enzyme is present, the reaction is quicker • An enzyme remains unchanged during the reaction and can be reused.

  5. Breakdown of Hydrogen Peroxide • Hydrogen Peroxide (H₂O₂) is a harmful by-product of reactions inside cells. • H₂O₂ can be broken down into water (H₂O) and oxygen (O₂). Hydrogen peroxide Water + Oxygen (H2O2) (H2O) (O2)

  6. Enzymes • Enzymes are biological catalysts • Catalase is an enzyme made by living cells, which can breakdown hydrogen peroxide • When a piece of living tissue is added, you can see bubbles of oxygen released • The more bubbles released, the more catalase is present in the tissue.

  7. Questions • What is meant by activation energy? • State 3 properties of a catalyst. • Where are enzymes found in living organisms? • Of what type of organic substance are enzymes composed? • Briefly explain why enzymes are needed for the functioning of all living cells.

  8. Enzymes • Catalase can only speed up the breakdown of hydrogen peroxide, NO OTHER REACTION. • It is said to be specific • Each enzyme can catalyse only one reaction • The substance that the enzyme catalyses is called the substrate

  9. Enzymes • Enzymes have an area on their surface which is a specific shape. • It is here that the substrate attaches. • This area is known as the active site. • The shape of the active site is determined by its chemical structure which results from bonding between amino acids in the enzyme molecule.

  10. Enzymes • The active site and substrate are said to be complementary • The substrate locks onto the enzyme at the active site and the reaction occurs. • This is known as the ‘lock and key’ theory.

  11. Enzymes • The reaction produces the products of the reaction. • Some enzymes are responsible for breaking down large substrates into small products • Some enzymes are responsible for building up small substrates into large products

  12. Questions • What determines the shape of an enzymes active site? • What name is given to the substance on which an enzyme acts? • Why is an enzyme said to be specific? • How is an enzyme thought to act according to the lock and key hypothesis?

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