LEAD Cumulative Quiz 1

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Appalachian State University *

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4580

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Chemistry

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Feb 20, 2024

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Name: _____________________ Chemistry 4600 - Fundamentals of Biochemistry LEAD Cumulative Quiz #1 September 25, 2022 Version A This exam is closed book. The use of a non-programmable calculator is allowed. The time for this exam is 50 minutes. Please use only the space provided for your answers and remember to show all work to receive credit. There are a total of 110 points on this test. Your score will be out of 100 points. 10 points will be extra credit 1. 5 pts. My research student treated cells with insulin in the lab. She saw no response. When she looked back over the instructions, she noticed that the instructions call for treating cells with 8 nM insulin. She used 4.5 x 10 -5 mg/mL insulin. Did she use enough? Prove it. The molecular weight of insulin is 5808 g/mol 2. Axitinib is a drug that is used for treatment of kidney cancer. The structure of axitinib is shown below. Absorption of Axitinib in the stomach depends on its charge. Charged molecules absorb better than uncharged molecules. pKa= 4.58 a. 5 pts. Use the Henderson-Hasselbalch equation to determine the ratio of charged to uncharged Axitinib at pH 2.5 b. 4 pts. Proton pump inhibitors are used to treat acid reflux and work by inhibiting stomach acid secretion. They can increase the pH of the stomach to 5. Would more axitinib be absorbed in the presence or absence of proton pump inhibitors?
c. 4 pts.Does axitinib contain an amide functional group? If so, circle on the molecule above. 3. Phosphohexose isomerase is a glycolytic enzyme that reversibly converts glucose 6-phosphate to fructose 6-phosphate. The production of fructose 6-phosphate has a ∆G˚’ of +1.67 kJ/mol at 25 C. Glucose 6-P Fructose 6-P a. 5 pts. Calculate the equilibrium constant for this reaction at 25 C. b. 5 pts. ∆G for this reaction in the body (37 C) is -2.9 kJ/mol. Determine the ratio of fructose 6-P to glucose 6-P under these conditions c. 3 pts. Based on your answers above, which best explains why the reaction is endergonic under standard conditions and exergonic under physiological conditions? - The concentration of fructose 6-P is maintained below its equilibrium concentration. - The concentration of glucose 6-P is maintained above its equilibrium concentration. - The concentration of glucose 6-P is maintained below its equilibrium concentration. - The concentration of fructose 6-P is maintained above its equilibrium concentration. 4. 5 pts. Glycerol Kinase catalyzes the following spontaneous reaction: Glycerol + ATP Glycerol 3-Phosphate +ADP Determine ∆G˚’ of the combined reaction using ∆G˚’ of it’s component reactions - Glycerol 3-Phosphate Glycerol + Pi ∆G˚’ = -9.2 kJ/mol - ATP ADP + Pi ∆G˚’ = -30.5 kJ/mol
5. 6 pts. Identify the following amino acids, include D or L in the name. 6. 5 pts. I am studying two proteins, Protein A and Protein B. Test tubes are prepared of each protein at 2 mg/ml concentrations. Both proteins have 1 tyrosine amino acid in their primary sequences. Protein A has 3 tryptophan amino acids in its primary sequence while Protein B has 2 tryptophan amino acids in its primary sequence. Measuring the A 280 of my samples, which one should have the higher absorbance? Why? 7. 12 pts. At what pH ranges, if any, would the peptides below exist as drawn?
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8. Class II Alcohol Dehydrogenase (pi-ADH) has a pI of 8.6. This enzyme isolated from the human liver facilitates the oxidation of ethanol to acetaldehyde while reducing NAD+ to NADH. a. 5 pts. Will pi-ADH have a net positive or net negative charge at pH 10? What about pH 7? b. 5 pts. At physiological pH, would we want to purify pi-ADH through anion exchange chromatography or cation exchange chromatography? c. 5 pts. I need to run my pi-ADH through dialysis to reduce my Tris buffer concentration from 100mM to 8 mM. I have 25 mL of protein in my dialysis tube, how much dialyzing buffer do I need? d. 5 pts. I need my ADH to be at least 10 mg/mL so I let it run in the speed vac overnight. I ran a Bradford assay and got the following standard curve. I had to dilute my protein 3x to fit within the linear range and got an absorbance value of 0.182. Is my pi-ADH concentrated enough?
e. 5 pts. The ∆G˚’ for the oxidation of ethanol to acetaldehyde is 47.2 kJ/mol. At 37 , what is the ∆G for this reaction given that we have 2.50 mM ethanol and 465 µM of acetaldehyde? 9. 6 pts. What amino acid produced the titration curve shown below? How many pKas are present? How many pI’s? 10. 10 pts. Draw an antiparallel beta-sheet. 11. 5 pts. A given reaction is endothermic and has a positive ∆S. When will this reaction be spontaneous? a. This reaction will always be spontaneous b. Low temperatures c. High temperatures d. This reaction cannot be spontaneous e. Not enough information given
12. 5 pts. We have learned that proteins are made of amino acid building blocks. Which organelle is responsible for building proteins from amino acids? a. Mitochondria b. Golgi complex c. Rough Endoplasmic reticulum d. Smooth Endoplasmic reticulum e. Lysosyme
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