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| Frage | Antworten |
| What is the role of enzymes? | Speed up chemical reactions by acting as biological catalysts Catalyse metabolic reactions (e.g. respiration and digestion) Affect structures in an organism as well as functions Can be intracellular or extracellular |
| Name examples of intracellular and extracellular enzymes | INTRA = catalase EXTRA = amylase, trypsin |
| Describe the structure and function of catalase | STRUCTURE: Intracellular 4 polypeptide chains and a haem group with iron FUNCTION: Catalyses H₂O₂ → O₂ + H₂O |
| Describe the structure and function of amylase | STRUCTURE: Extracellular Found in saliva Secreted by cells in salivary glands FUNCTION: Catalyses starch → maltose |
| Describe the structure and function of trypsin | STRUCTURE: Extracellular Produced by pancreas Secreted into the small intestine FUNCTION: Hydrolysis of peptide bonds |
| Complete the sentences: Enzymes are _______ proteins. They have an ________ ______ (where the substrates bind to). The active site has a specific _______ (determined by the enzyme's _______ structure). | Enzymes are GLOBULAR proteins. They have an ACTIVE SITE (where the substrates bind to). The active site has a specific SHAPE (determined by the enzyme's TERTIARY structure). |
| Complete the sentences: For enzymes to work, its shape has to be _______________. This means that enzymes are very _________. When a substrate binds to an enzyme, an ______-_____ complex is formed. | For enzymes to work, its shape has to be COMPLEMENTARY. This means that enzymes are very SPECIFIC. When a substrate binds to an enzyme, an ENZYME-SUBSTRATE complex is formed. |
| How do enzymes speed up reactions? |
Enzymes reduce the amount of activation energy, making reactions happen at a lower temperature. This speeds up the rate of reaction.
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| What is activation energy? | The amount of energy needed to be supplied to the chemicals before the reaction will start |
| How does forming an enzyme-substrate complex lower the activation energy? | ANABOLIC Building up molecules Attaching substrates to the enzyme holds them close together, reducing any repulsion so they can bond more easily CATABOLIC Breaks down molecules Fitting into the active site puts a strain on bonds in the substrate; the substrate molecule breaks up more easily |
| What are buffers? | Buffers resist changes in pH and can accept or donate H⁺ ions |
| What are the two models for the mechanism of enzyme action? | Lock and key model Induced fit model |
| What is the lock and key model? |
The substrate fits into the enzyme like a lock and key; the active site and substrate have a complementary shape
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| What is the induced fit model? |
The substrate does not only have to be the right shape to fit the active site, it has to make the active site change shape in the right way as well
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| What is the temperature coefficient? | The Q₁₀ value shows how much the rate of reaction changes when the temperature is raised by 10°C. At temperatures before the optimum, a Q₁₀ value of 2 means the rate doubles when the temperature is raised by 10°C. Most enzyme-controlled reactions have a Q₁₀ value of around 2 |
| What is the reaction for the temperature coefficient? | Q₁₀ = rate of reaction at (T+ 10)°C / rate of reaction at 10°C |
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