Bio study guide exam 21. How do the laws of thermodynamics relate to our study of metabolisma. We can relate this because even though were doing all of these processes and making energy and stuff were not really making energy were just converting it from different forms2. what is meant by an equilibrium constant – what does this value tell you about thereactiona. an equilibrium constant is concentration balance between the two sides in a reaction – ratio of two begins to be a constant – this value tells you the ratio at which the reaction is the most stable3. how does the equilibrium constant relate to the free energy of the reactiona. it relates because the higher the equilibrium constant the more energy that can be used as it rushes to balance out the reaction4. How do enzymes work? – What is the difference between active sites and allosteric sites? Can the same molecule bind to both active and allosteric sitesa. enzymes work by lowering the energy needed for a reaction to happenb. An active site is the place that substrates bind in order for the enzyme to catalyze the reaction whereas the allosteric site is the place where the activity of that enzyme can be turned on or offc. The same molecule cannot bind both to the active site and allosteric site because the substrate will make the product but having too much substrate would only tell the enzyme to begin catalyzing reactions not turn it off5. How are enzymes activated and inactivated? Why is this important? What are the important allosteric enzymes in the pathways that we’ve covered?a. Enzymes are activated and inactivated though allosteric control, - allosteric activator and repressors, or through the covalent bond attachment of a phosphate group changes the shape of the active site, and enzyme inhibitors (competitive and noncompetitive, reversible and non reversible)b. This is important because the cell doesn’t always want the enzyme to be active and so needs a way to turn it off. The important allosteric enzymes that we have covered are such like phosphofructokinase,6. How does methyltrexate work as a cancer chemotherapy agent?a. methyltrexate works as a cancer chemotherapy agent because it is recognized really easily by the enzymes that promote cell division and use folic acid normally, so when they bind methyltrexate it permanently changes their structure and so cannot continue dividing and die7. What are coenzymes and cofactors and how do they work?a. Coenzymesi. Small organic molecules that attach to enzymes on or near the active site to help form the correct active site to help things bind betterb. Cofactorsi. Prothetic groups –are substances that associate directly with enzyme and are required for reactions to proceed – coenzymes are cofactors8. what are enzyme inhibitors – why are they important – what is the difference a. enzyme inhibitors are artificial or foreign poisons that disable any enzyme that can bind to them – are permanentb. they are important b/c penicillin uses them to block the enzymes of the virus causing the illness and allowing the immune system to then kill off the virusc. are different because can bind to the active site or anywhere on the enzyme and disrupt the active site enough to stop the enzyme from working9. Between competitive and non competitive inhibitors – can the binding of inhibitors be reversible?a. There are reversible inhibitors and non reversible – both competitive and non competitive inhibitors seem to sometimes be reversible10. Why is ATP so important? What are three ways that ATP is generated? – How arethese ways different?a. ATP is so important because without it we wouldn’t be able to do anything or move or have any internal functions operate b. ATP is generated through glycolysis, alcohol fermentation, and lactic fermentationc. These three ways are different because alcohol and lactic fermentation make much less ATP as compared with glycolysis and are also much simpler11. What are oxidation/reduction reactions? Dehydration reactions - hydrolysis reactionsa. oxidation/reduction reactions are the transfer of electrons between two molecules – such as when a NADH gets oxidizedb. dehydration reactions are when an h2o gets taken out of a molecule and a hydrolysis reaction is when it gets added to one12. what are the substrates and products of glycolysis – the citric acid cycle – gluconeogenesis – where do these pathways take place – why is it important for cells to control the activation and inactivation of phosphofructokinase and pyruvate dehydrogenase – how are their enzymes controlleda. substrates and products of glycolysisi. 1 molecule of glucose – 2 ADP – 2 Piii. 2 pyruvate – 2 ATP – 2 NADH b. substrates and products of gluconeogenesisi. 2 pyruvate – 4 ATP – 2 NADH - 2 GTPii. Glucose - 2 NAD+ - 4 ADP – 2 GDP -6 Pic. substrates and products of citric acid cyclei. Acetyl CoA – 2 h2o – 3 NAD+ - CoA – SH – GDP – FAD+ii. H2O –2 CO2 – 2 NADH – ATP – FADH2d. It is important for the cell to control activation and inactivation of phosphofructokinase to control whether resources are being used to startglycolysis. – pyruvate dehydrogenase – because if already too much ATP then not necessary to make more at the moment and so can be stored as fatty acid until times of crisise. The enzymes are allosterically controlled by the product or ATP 13. what are some similarities and differences between respiration and fermentationa. similaritiesi. both make ATPii. both are exergonicb. differencesi. fermentation can take place without oxygenii. can form either lactic acid( in muscles) or alcohol ( in yeast/other grains)14. what is meant to say a reaction is endo- or exo – gonica. if a reaction is endergonic then it needs energy to happen and if its exergonic than it will release energy either as heat or ATP15. what are the basic steps of the respiratory chain – why is o2 required – how is ATP generatedi. 4 protein complexes and one organic molecule embedded in the inner membrane of the mitochondria or plasma membraneii. Electron transport chain with the NADH gets electrons from the oxidation and loses 2 h+iii. ATP is generated by having the electrons go down the electron transport chain and get spit out into the space between the inner and outer membrane this creates a pressurized space and then the H+’s go whizzing through the ATP synthase which makes shitloads of ATPb. O2 is required because it is the final
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