enzymes flashcards

All 25 cards

1. Card 1

   Define the term metabolism.

   Metabolism is the sum of all chemical reactions that take place within an organism. It encompasses both anabolic reactions (building up) and catabolic reactions (breaking down) that control the chemical and energy requirements of a cell.

2. Card 2

   What is an enzyme?

   An enzyme is a protein catalyst found in living organisms that speeds up chemical reactions without being used up in the reaction. Enzymes are crucial for controlling cell metabolism.

3. Card 3

   Describe the protein nature and folded structure of enzymes.

   Enzymes are proteins composed of long chains of amino acids that fold into a very specific three-dimensional globular shape. This precise shape, particularly the active site, is essential for the enzyme to function and attach to its specific substrate.

4. Card 4

   Explain the role of enzymes in metabolism in plants and animals.

   Enzymes play a critical role in metabolism by controlling all chemical reactions within an organism. In both plants and animals, they facilitate reactions that obtain and utilize energy, such as breaking down food (catabolic) or building complex molecules (anabolic).

5. Card 5

   How does an enzyme function according to the active site theory (Lock and Key model)?

   According to the lock and key model, an enzyme functions because its active site has a complementary shape to its specific substrate. The substrate binds to the active site, forming an enzyme-substrate complex, where the reaction occurs, either breaking bonds or encouraging new ones.

6. Card 6

   Explain what is meant by the specificity of an enzyme.

   Enzyme specificity refers to an enzyme's ability to react with only one particular substrate or a very limited range of substrates. This is due to the unique three-dimensional shape of its active site, which only allows molecules with a complementary shape to bind and react.

7. Card 7

   What is the effect of pH on enzyme action?

   pH affects enzyme action by influencing the hydrogen bonds that maintain the enzyme's specific shape. Deviations from the optimum pH can alter the active site's shape, reducing the enzyme's efficiency, and extreme pH changes can cause denaturation, permanently losing its function.

8. Card 8

   What is meant by the 'optimum' pH of an enzyme?

   The optimum pH of an enzyme is the specific pH value at which the enzyme exhibits its maximum activity and efficiency. At this pH, the enzyme's active site has the best fit for its substrate, allowing for the fastest reaction rate.

9. Card 9

   Explain how high temperatures denature enzymes.

   High temperatures cause the molecules to vibrate more vigorously, breaking the hydrogen bonds that maintain the enzyme's specific three-dimensional shape, particularly the active site. This permanent change in shape, known as denaturation, renders the enzyme unable to bind to its substrate and thus unable to function.

10. Card 10

    Describe the process of immobilising enzymes.

    Immobilising enzymes involves attaching biological catalysts to an inert material, either chemically or physically. This process prevents the enzymes from being freely dissolved in the reaction mixture, allowing for their reuse and easier separation from products.

11. Card 11

    What are the advantages of using immobilised enzymes in bioreactors?

    Advantages of immobilised enzymes include their reusability, which leads to cheaper production costs. They remain within the bioreactor, simplifying product separation, and often exhibit increased stability, leading to more efficient processes.

12. Card 12

    Describe the nature and role of ATP in cells.

    ATP (adenosine triphosphate) is a molecule composed of adenine, ribose sugar, and three phosphate groups. Its primary role in cells is to trap and transfer small amounts of energy for various cellular reactions, making it the main energy currency of the cell.

13. Card 13

    Describe the production of ATP from ADP, phosphate, and energy.

    ATP is produced when ADP (adenosine diphosphate) combines with an inorganic phosphate group, requiring the input of energy. This process, called phosphorylation, occurs during cellular respiration and photosynthesis, effectively storing energy in the newly formed phosphate bond.

14. Card 14

    Explain the role of NAD+ in the transfer of electrons and hydrogen ions in catabolic reactions.

    In catabolic reactions, NAD+ acts as a coenzyme that accepts released hydrogen ions and electrons, becoming reduced to NADH. NADH then carries these hydrogen ions and electrons, which can be later oxidized to release energy in small quantities for ATP synthesis.

15. Card 15

    Explain the role of NADP+ in the transfer of electrons and hydrogen ions in anabolic reactions, specifically photosynthesis.

    In anabolic reactions like photosynthesis, NADP+ is present in chloroplasts and accepts light energy to form NADPH. NADPH then donates hydrogen ions to reduce carbon dioxide, facilitating the manufacture of more complex chemicals like sugar.

16. Card 16

    Distinguish between catabolic and anabolic reactions within the context of metabolism.

    Catabolic reactions involve breaking down complex molecules into simpler ones, releasing energy (e.g., respiration). Anabolic reactions, conversely, involve building up complex molecules from simpler ones, requiring an input of energy (e.g., photosynthesis).

17. Card 17

    How do enzymes speed up chemical reactions?

    Enzymes speed up chemical reactions by reducing the activation energy required for the reaction to proceed. They do this by binding to the substrate at the active site, straining bonds in catabolic reactions or bringing molecules together in anabolic reactions.

18. Card 18

    What is the 'Induced Fit Model' of enzyme action?

    The Induced Fit Model suggests that the active site of an enzyme is not a rigid, fixed shape. Instead, when the substrate binds to the enzyme, it induces a slight change in the shape of the active site, allowing for a more precise fit and optimal catalysis.

19. Card 19

    Why are enzymes described as having a '3D globular shape'?

    Enzymes are described as having a 3D globular shape because their long chains of amino acids fold into a complex, compact, spherical structure. This specific three-dimensional conformation is crucial for forming the active site and enabling the enzyme to recognize and bind to its substrate.

20. Card 20

    What is a substrate in an enzyme-controlled reaction?

    A substrate is the specific chemical molecule with which an enzyme reacts. It binds to the enzyme's active site, where it is then converted into one or more products through the enzyme's catalytic action.

21. Card 21

    Give an example of a catabolic enzyme and its function.

    Amylase is a catabolic enzyme that converts starch into maltose. It breaks down the larger starch molecules into smaller maltose molecules, as seen in digestion or seed germination.

22. Card 22

    Give an example of an anabolic enzyme and its function.

    DNA Polymerase is an anabolic enzyme that forms and repairs DNA. It converts simpler molecules into a more complex form, building larger DNA strands from smaller units.

23. Card 23

    What happens to an enzyme if the pH is significantly outside its optimum range?

    If the pH is significantly outside an enzyme's optimum range, the enzyme will denature. This means it loses its specific three-dimensional shape, particularly at the active site, and can no longer bind to its substrate or catalyze reactions effectively.

24. Card 24

    Why is cellular energy, stored in the bonds of biomolecules, important for organisms?

    Cellular energy, stored in the bonds of biomolecules, is vital because organisms break down these energy-rich molecules through processes like respiration. This releases the stored energy, which is then utilized for various metabolic activities and to produce ATP.

25. Card 25

    What is phosphorylation and when does it occur in the context of ATP?

    Phosphorylation is the addition of a phosphate group to a molecule. In the context of ATP, it refers to the process where ADP (adenosine diphosphate) gains a phosphate group and energy to form ATP (adenosine triphosphate), effectively storing energy.

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