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21 Cards in this Set
- Front
- Back
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What is an enzyme? |
Biological catalyst. Speeds up and controls chemical reactions, without itself being changed in the reaction. Enzymes can be reused. |
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What are enzymes made from? |
Protein |
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Where are enzymes made? |
Ribosome |
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Role of enzyme |
To speed up and control chemical reactions without itself being changed in the reaction. |
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What is meant by the specificity of enzymes? |
A particular enzyme can only catalyse one particular chemical reaction ie. The enzyme amylase can break starch down into maltose but cannot break down proteins. |
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What is the active site of an enzyme? |
An area in the protein structure of an enzyme into which the complimentary shaped substrate molecule fits to form the enzyme-substrate-complex. |
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How does an enzyme work? / Mechanism of enzyme action. |
By joining with a substrate to form the enzyme-substrate-complex. In the ESC a chemical reaction takes place. The product is formed and the enzyme is released unchanged. |
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What is a denatured enzyme? |
Enzyme that has undergone a change (usually irreversible) in the shape of its active site. The new shape is no longer complimentary to the substrate molecule and so the ESC cannot be formed. The enzyme has lost its ability as a catalyst. |
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How can an enzyme be denatured? |
1. High temp 2. Vigorous stirring 3. Incorrect pH 4. Radiation |
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What is an enzyme inhibitor? |
A chemical that binds to an enzyme blocking its active site. The enzyme can no longer bind with its substrate. Cyanide is a respiratory enzyme inhibitor. |
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What are the factors that affect enzyme activity? |
1. Temperature 2. pH 3. Volume of enzyme 4. Volume of substrate |
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What is an immobilised enzyme? |
Enzyme that is not free in solution but instead is trapped in a bead or gel. |
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What are the advantages of using immobilised enzymes? |
1. Can be reused -saves money. 2. Product comes out clean -saves time and money on production. 3. Reaction reversal is avoided -enzyme is not present in product. |
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What are the uses of immobilised enzymes? |
1. Glucose Isomerase to convert glucose to fructose -F x2 sweet as G. 2. Convert original penicillin into a semisynthetic antibiotic that is active against bacteria. 3. Can be immobilised into plastic strips which are then used to detect specific substances eg. Clinistix. |
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What is meant by optimum pH? |
pH at which an enzyme works best ie. maximum number of ESC formed and max no. of product made. |
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Enzymes are highly specific - explain. |
•A particular enzyme can only catalyse one specific type of chemical reaction eg. Amylase breaks down starch but will not work on any other substances. •This high specificity is due to the shape of the active site of the enzyme, which will only bind with substrates molecules which have a complementary shape. •Specificity is further shown denaturation ie. When an enzyme undergoes a change in the shape of the active site - it can no longer form the ESC and so loses its ability as a catalyst. |
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Explain the lock and key theory. |
•On the surface of an enzyme are areas called active sites. •The complex 3D shape of the active site will only fit neatly into a substrate, whose shape is complimentary to it. •It was originally thought to be so strictly complimentary a match between the enzyme and substrate that it was referred to as the lock and key theory. |
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Explain the induced fit model. |
•It is now believed that the shape of the active site is not as rigidly fixed as once thought ie. the shape of the active site of the enzyme and the shape of the substrate are closely (not precisely) complimentary. •When the substrate attaches to the active site, the shape of the active site changes slightly, fitting into and enclosing the substrate more tightly and exactly to form a snug ESC. •This change in the active site to accommodate the substrate is called "an induced fit". •Within the ESC a chemical change occurs. The product is formed and is released. •The enzymes active site recoils to its original shape and is free to act again. |
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What is the optimum pH and temp for plants? |
pH 7,8,9. Temp 22-28°C |
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What is the optimum pH and temp of animal enzymes? |
pH 7,8 Temp 37°C |
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What is the optimum pH of protease? |
2 |
