Outcomes 1-3 Revision Questions PDF

**Outcomes 1-3** **Revision Questions** 1. Researchers have been studying an enzyme called \'Catalase A\' which is known to break down hydrogen peroxide. They analysed its activity at various substrate concentrations and different pH levels. The resulting data provided the following i...

**Outcomes 1-3** **Revision Questions** 1. Researchers have been studying an enzyme called \'Catalase A\' which is known to break down hydrogen peroxide. They analysed its activity at various substrate concentrations and different pH levels. The resulting data provided the following insights: pH Activity Level Substrate Concentration (mM) ---- ---------------- ------------------------------ 3 Low 10 4 Medium 20 5 High 30 6 High 40 7 Medium 50 8 Low 60 a. Based on the data, what can you infer about Catalase A\'s optimal conditions for activity? 1 mark It has an optimal pH of 5-6 and shows maximum activity at substrate concentrations between 30-40 mM, 1 mark b. Explain what is occurring at pH 3 to the protein 1 mark pH 3 modifies (+) and (-) charged amino acid side chains, affecting their ability to form ionic and polar interactions, 1 mark c. Name the bonds involved in catalase A when binding to Hydrogen bonds, ionic bonds, hydrophobic interactions and Van der Waals, 1 mark 2. Explain why the inclusion of dithiothreitol (DTT) in the sample buffer is helpful in analysis of proteins 2 marks 3. Low temperatures reduce protease enzyme activity, slowing protein degradation. What do high temperatures beyond the optimum do to protein activity? 1 mark 4. State the term used to describe the model of enzyme action where the enzyme can interact with more than one substrate and give an example of an enzyme that uses the model of binding 5 marks 5. Define the term cryoprotectant 1 mark 6. Name a suitable cryoprotectant in the laboratory for storing proteins 1 mark 25-50% glycerol, 1 mark 7. Cocktails of protease inhibitors are used in the laboratory to prevent the protein from proteolysis from a range of protease enzymes 8. Define the term structural analogue 1 mark 9. a. Describe the difference between a structural analogue and a ligand 1 mark b. State the role of a structural analogue 1 mark 10. Name an example of a cofactor 1 mark 11. Describe how X-Ray crystallography works and how it is helpful in protein studies 4 marks 12. When carrying out experimentation in the laboratory and you wish to determine the location of amino acids, there are methods of doing this. a. Particular amino acids that are suspected to be crucial to enzyme function are chemically modified as one method to do this. Particular amino acids that are suspected to be crucial to b. Describe another method of doing this 3 marks 13. a. State what is meant by the term zymogen and give an example 1 mark An inactive precursor of an enzyme, chymotrypsinogen, pepsinogen or any correct example, 1 mark c. Describe how SDS-PAGE can be used to determine if a precursor has undergone protein processing to yield the mature form of the protein 1 mark SDS-PAGE can be used to demonstrate difference in sizes with the precursor being larger than mature version of enzyme, 1 mark 14. Protein Kinase A has two regulatory subunits and two catalytic subunits. a. Explain how these catalytic subunits start a phosphorylation cascade 2 marks b. Describe how these subunits are being released 4 marks 15. a. State the role of cyclin-dependent kinases 1 mark 16. Binding by proteins to regulate other proteins is one mechanism of protein regulation, name two other methods of protein regulation 2 marks 17. Describe **two** of these other methods in detail using named examples A method of allosteric regulation that leads to conformational change that causes conformational change is the binding of ATP at a site different from the active site/allosteric site of phosphofructokinase (PFK) (1 mark). This acts as a 18. Explain how the **consensus sequence is useful in protein regulation** **2 marks** 19. Name the key enzymes involved in protein regulation through phosphorylation including an example target enzyme for each 2 marks Kinases catalyse phosphorylation (1 mark) Phosphatases catalyse dephosphorylation (1 mark) 20. Explain how urea denatures proteins 2 marks Total Marks = 50 Pass Mark = 30