241L Final
For affinity chromatography, the partition coefficient (K) for the analyte of interest is... A. 0 B. 0.5 C. 1 D. Depends on the type of buffer used as the MP.
C. 1
In today's lab experiment you will construct what type of plot to determine the pKa of bromothymol blue? A. Standard calibration plot. B. Standard addition plot C. Derivative Plot D. Second Derivative Plot E. Titration Curve
C. Derivative plot
If a piece of glassware breaks during your experiment, the first thing you should do is: A. Pick up the broken pieces of glass and dispose of the in the glass waste box. B. Sweep up the broken pieces and dispose of them in the glass waste box. C. Inform the TA and ask for assistance. D. Go to Morehead 102 and purchase your replacement glassware.
C. Inform the TA and ask for assistance.
GC: Which of the below is the correct elution order for the compounds you will see in your chromatograms today? A. pentanol --> water --> ethanol B. ethanol --> pentanol --> water C. ethanol --> water --> pentanol D. water --> ethanol --> pentanol
C. ethanol --> water --> pentanol
The spectrophotometric enzyme assay ___________________? A. Involves one enzymatic reaction. B. Is not useful in this experiment. C. Indirectly determines the amount of glucose in the solution. D. Directly determines the amount of glucose in the solution.
C. indirectly determines
The Bradford Assay uses the shift of ________ when the dye binds to protein. A. pH B. fluorescence intensity C. maximum absorbance D. quantum efficiency of the fluorescently labeled protein
C. maximum absorbance
Calculate the molar absorptivity of bromothymol blue at 620 nm if the percent transmittance (% T) is determined to be 15.1% at this wavelength. The pathlength of the cuvet is 10.0 mm and the concentration of bromothymol blue solution is 5.00 x 10-5 M. A. 1.41 x 104 M-1 cm-1 B. 4.10 x 10-5 M-1 cm-1 C. 3.02 x 104 M-1 cm-1 D. 1.65 x 104 M-1 cm-1
D. 1.65 x 104 M-1 cm-1
You take 10.0 mL of your unknown solution and dilute it to 100. mL. You then determine that the concentration of this diluted sample is 0.25 M. What was the concentration of the original (undiluted) sample? A. 0.40 M B. 0.025 M C. 40. M D. 2.5 M
D. 2.5 M
How will you determine when to switch mobile phases during your chromatographic run? (LC) A. When the voltage on the chromatogram in your lab manual is the same as the voltage of your recorded data. B. Go by the time scale on the chromatogram provided in your lab manual. C. The spectrophotometer will prompt you as to when to switch the mobile phases. D. After the appearance of the correct number of peaks as indicated in the chromatogram in your lab manual.
D. After the appearance of the correct number of peaks as indicated in the chromatogram in your lab manual.
In today's experiment (affinity) you will use _________ to construct your calibration plot? A. Bromothymol blue B. None of the above C. Standard solutions of your assigned protein (apple, citrine or green-fluorescent protein). D. Bovine Serum Albumin E. Coomassie Brillian Blue
D. BSA
When setting up the gel run you will do which of the following? A. set the voltage to 200 V and run for 10 min to concentration the sample and then set the voltage to 100 V to run for 40 minutes B. Set the voltage to 100 V and run for 40 minutes C. Set the voltage to 200 V and run for 40 minutes D. Set the voltage to 100 V for 10 min to concentrate the sample and then set the voltage to 300 V and run for 15-20 min.
D. Set the voltage to 100 V for 10 min to concentrate the sample and then set the voltage to 300 V and run for 15-20 min.
When working with the pH probes, which of the following statement is true: A. None of these statements are true B. You should vigorously scrub the end of the electrode to ensure it is clean C. There is no need to clean the electrode today D. You should very carefully dab the end of the electrode when cleaning so it does not get damaged
D. You should very carefully dab the end of the electrode when cleaning so it does not get damaged
bromothymol blue: At the inflection point of your Absorbance vs. pH plot, _____________. A. The isoelectric point (pH) has been reached B. pH = pKa C. [HIn] = [In-] D. All of the above E. B and C F. A and B
E. B and C
You will first lyse your samples in lab and then run the lysed sample on the affinity column to purify the protein. T/F
F
You remember that you left your lab manual in your lab room yesterday after leaving Morehead. You stop by the lab room the next day before labs start and find that your lab room is open and no chemical work is being done. Which of the below statements are true? A. You may enter the lab room and pick up your manual because no chemical work is being done in the lab room. B. You must find someone on the lab staff to accompany you into the lab room to pick up the manual that you left behind. C. You must wait until next weeks lab. D. You may email your TA and ask if they can go to the lab room and pick up your manual or meet you to escort you to the lab room. E. All of the above F. B and D G. A and C
F. B and D
True or False: When calibrating your pH electrode using the Vernier software, you immerse the electrode into the standard buffer solution, wait for the reading on the software screen to reach the pH value of the standard buffer solutions (e.g., 4.00) and then click on KEEP.
FALSE. you don't want for the reading to reach 4, you just enter 4
It is alright to bring a small beaker of pentanol to the GC room in order to clean your GC needle in between injections? True False
False
Since sucrose contains both glucose and fructose, a solution of sucrose can be analyzed using the same method as outlined for this experiment. T/F
False
You are permitted to adjust the flow rate if, after your measurement of the flow rate, it is found to be too high or too low? True False
False
In this experiment an open tubular type column is used within the GC. T/F
False, packed
If you injected a mixture containing heptane (boiling point 98 ˚C), pentane (bp 36 ˚C), hexane (bp 69 ˚C) and octane (126 ˚C) onto a Carbowax 20M column, the compounds would come off in what order (first to last)?Match the order in which each compound will elute from the column. A. Second B. First C. Third D. Fourth
First - pentane second - hexane third - heptane last - octane
Which of the following can be used as carrier gases in GC? A. He B. N2 C. H2 D. Ar E. All of the above F. A, C and D G. A, B and C
G. A, B, C`
In which of the following locations are you required to have your safety goggles covering your eyes at all time? A. In your lab room. B. In Morehead Labs room 408A, where the TA office hours are held C. In the GC room. D. In the UV/Vis spec room. E. All of the above F. A and B G. A, C and D
G. A, C and D
Which of the following statements is/are correct: A. When leaving the lab room, it is acceptable to leave my gloves on if I have just put a pair of clean gloves on my hands. B. When leaving the lab room with chemicals, I must place them on a cart, or in one of the rubber black carriers to prevent chemicals from spilling in the hallways/elevators. C. When exiting the lab room, I must first take my gloves off and dispose of them in the trash D. When leaving the lab room with chemicals it is ok to carry them in my hand throughout the hallways/elevators. E. When exiting the lab room I must first take off my gloves and dispose of them in the glove recycling containers provided on the same lab bench where I got my clean gloves. F. All of the above G. B and E H. A, B D
G. B and E
In today's lab, GC, which salt will you add to your solutions in order to maximize the amount of ethanol extracted?
NaCl
In SDS-PAGE, sodum dodecyl sulfate (SDS) is added to... A. Break any disulfide bonds B. to impart a negative charge to the proteins. C. to linearize the proteins D. Both A and B E. Both B and C
SDS PAGE imparts a negative charge and linearizes the proteins E. Both B and C
Always add the protein sample to water, never the opposite. True False
True
Ethyl acetate is flammable so needs to be handled with caution. True False
True
In this experiment you are trying to determine _____________. A. the wavelength at which the acidic and basic forms of bromothymol blue absorb maximally. B. the concentration of bromothymol blue. C. the partition coefficient of bromothymol blue in a water-ethyl acetate mixture. D. the pKa of bromothymol blue
a, b, d
Which of the following situations should you report to your TA if they occur in lab (select all that apply)? A. You spill dilute acid on your arm. B. You or someone else in lab feels faint and/or has fainted C. Even though you were supposed to leave them on, you removed your goggles for a minute at your lab bench and in the process you think you got something in your eye. D. You burned your finger on a hot piece of glass
all
High concentration of ________ molecules are in the buffer used to elute the protein because they outcompete the His tag in binding to the nickel ions on the resin stationary phase. A. Urea B. Dihydrogen phosphate (H2PO4-) C. imidazole D. NaCl
c. imidazole
What are the main classes of pigments found in plants, like the spinach you will use today? A. Porphyrins B. Phycobilins C. Flavenoids D. Carotenoids E. Melanin F. All of the above G. A, B and C H. A, C and D I. B, C and E
porphyrins, flavenoids, carotenoid H. A, C, and D
Calculate the partition coefficient if the concentration of the ethanol in the organic layer is 0.02M and the concentration of ethanol in the aqueous layer is 0.04M
0.5
Rank the following from strongest acid to weakest acid based on their Ka (1 = strongest, 4 = weakest) A. Ka = 7.9 x 10-7 B. Ka = 8.6 x 10-4 C.Ka = 6.5 x 10-8 D. Ka = 2.4 x 10-7
1. B 2. A 3. D 4. C (biggest to smallest Ka)
Which combination(s) of equal volumes of the below reactants would result in the formation of a buffer? 1. 0.10 M CH3COOH and Water 2. 0.10 M CH3COOH and 0.05 M NaOH 3. 0.1 M CH3COO- and 0.05 M HCl
2 and 3
If a standard addition plot was constructed for a given analysis and the linear regression gave you a slope of 1.25 and a y-intercept of 3, what is the percentage of ethanol in the sample?
2.4% set y = 0 and solve for x
You add 100 mL of 0.10 M HCl to 100 mL of 0.50 M phosphate (H2PO4-; pKa = 2.148). What is the pH of this solution?
2.75
What are the forces that dictate the how the pigments will separate along the column? A. Electrostatic B. Hydrogen bonding C. Friction D. Dipole-Dipole
A and D
What factors affect the separation of compounds in gas chromatography? A. Temperature of the column B. Temperature of the injection port C. flow rate of the carrier gas D. boiling point of compounds E. none of the above will affect separation
A, C, D
You have a solution that you wish to dilute 50 times (50x). Which of the below represents a 50x dilution? A. 1.0 mL of a solution diluted to 50.0 mL B. 50 mL of the solution diluted to 1.0 mL C. 25 mL of a solution diluted to 50 mL D. 25 mL of a solution diluted to 100 mL
A. 1.0 mL
When making your absorbance measurements, you must fill the cuvette _____ full with solution. A. 3/4 B. 1/4 C. to the top D. 1/2
A. 3/4
Affinity: You will wait approximately _____ minutes for the dye to bind the protein. A. 5 B. 10 C. 15 D. 30
A. 5
Affinity lab: You will make absorbance measurements at _________. A. 595 nm B. 465 nm C. 625 nm D. 340 nm
A. 595 nm
How will you dispose of your solutions today? (LC, spinach) A. All solutions go into the liquid waste container. B. Only solutions that contain ferrocyanide/ferricyanide solution are disposed of in the liquid waste container. C. Solutions that contain phosphate buffer and ferrocyanide/ferricyanide solution go into the liquid waste container, all other solutions can be dumped down the sink. D. All the solutions can go down the sink after they have been diluted with large amounts of water.
A. All solutions go into the liquid waste container.
Where should you place your backpack when you come to lab? A. In the cabinets under the white board labeled for backpack storage. B. There is no designated area for backpacks. C. In your lab drawer. D. On the floor next to your lab drawer. E. On the ledge above your lab bench.
A. In the cabinets under the white board labeled for backpack storage.
When you are finished using a disposable glass Pasteur pipette, where should you dispose of it? A. In the designated glass waste container in the lab room. B. In the trash can at the end of the lab benches. C. Clean it for use in another experiment. D. In the solid waste container in the hood.
A. In the designated glass waste container in the lab room.
If your GC syringe needle breaks or is bent during the experiment you should do which of the following? A. Let your TA know. B. Place it in the GC syringe bin labelled "Clogged" and obtain a new syringe from the syringe bin. C. Share a syringe with the group next to your instrument. D. Write "broken needle" on the syringe box, place in the syringe bin and obtain a new syringe from the GC Needle bin.
A. Let your TA know
When obtaining reagents from the main lab hood for your experiment, which of the following indicated the proper technique? A. Pour a small amount into a beaker or flask, cover and bring it back to your lab bench. B. It depends on the instructions that your TA provides during the pre-lab lecture. C. Obtain the stock bottle from the hood and carefully bring it to your bench. When finished, pass it along to the next student/group. D. Go to the main hood, wait your turn and pipette directly out of the stock bottle.
A. Pour a small amount into a beaker or flask, cover and bring it back to your lab bench.
How should the Ferrocyanide and Ferricyanide solutions be disposed of? A. Pour them into the waste bottle in the hood B. Neutralize with base, then flush down the sink C. Put them in a covered flask for next week's lab D. Flush them down the sink with plenty of water
A. Pour them into the waste bottle in the hood
For a solute (S) partitioning between aqueous and organic solvents you can write K = _______. A. [S]organic/[S]aqueous B. ([S]organic/[S]aqueous)n C. ([S]aqueous/[S]organic) x qn D. ([S]organic/[S]aqueous) x qn E. ([S]aqueous/[S]organic)n F. [S]aqueous/[S]organic
A. [S]organic/[S]aqueous
The eyewash in my lab is located: A. At the front sink B. By the entry door C. In the hallway D. At my work station
A. at the front sink
You put a flask containing a solution of benzoic acid and organic solvent on a hot plate at a medium setting in order to evaporate off the organic solvent. Your TA has told you it will take 15 min. After 5 min you realize you have to use the restroom. You should do which of the following? A. Place a watch glass on top of the flask and then quickly go to the restroom. B. Turn the hot plate to LOW and then go to the restroom. C. Ask your TA to watch your experiment so you can go to the restroom. D. Since you have 10 minutes until the solvent completely evaporates, you may quickly go to the restroom.
Ask your TA to watch your experiment so you can go to the restroom.
You are instructed to make a 2% ethanol in pentanol solution using a 10 mL volumetric flask. What are the correct steps to take? A. After adding the ethanol to the 10 mL flask, fill the flask with pentanol to the mark. B. After adding the ethanol to the 10 mL flask, add a small amount of pentanol to the flask and swirl to mix the solution. Then add pentanol to fill up to the mark. C. Measure out 0.2 mL of ethanol and add to the 10 mL volumetric flask. D. Measure out 9.8 mL of pentanol and add to the 10 mL volumetric flask
B and C
Calculate the partition coefficient if 1/3 of a 10% ethanol sample is extracted from the aqueous phase with 1-pentanol. (Hint: K = [CH3CH2OH]org / [CH3CH2OH]aq) A. 0.66 B. 0.5 C. 0.33 D. 1.0
B. 0.5
While taking your pre-lab quiz and listening to your pre-lab lecture, you are not required to wear your safety goggles. A. True B. False
B. False
You are permitted to have a bottle of water outside your book bag in the lab room as long as it is securely capped or has a lid? A. True B. False
B. False
You wish to prepare a buffer with a pH of 4.00. Which of the below combinations would be best to prepare this buffer? A. H3PO4 and H2PO4- (pKa = 2.12) B. HCOOH and HCOO- (pKa = 3.74) C. H2CO3 and HCO3- (pKa = 6.38) D. CH3CO2H and CH3CO2- (pKa = 4.74)
B. HCOOH and HCOO- (pKa = 3.74)
What is the correct way to mix water and acid A. Slowly add water to acid B. Slowly add acid to water C. It does not matter which is added first as long as it is done slowly
B. Slowly add acid to water
After adding the saturated NaCl solution to the spinach extract in the separatory funnel, you should add more of which of the below to help extract more spinach into the organic phase. A. Ethyl Acetate B. Acetone C. Acetonitrile D. Saturated NaCl solution
B. acetone (if after adding 1 mL of acetone, still no separation, then add solid NaCl)
Gas Chromatography is a great technique for the analysis of what types of samples? A. Proteins B. Liquid samples that are volatile. C. High Molecular Weight Polymers D. Liquid samples that are non-volatile.
B. liquid samples that are volatile
In today's experiment, (affinity protein) each group will work with... A. a mixture of two different fluorescencetly-tagged proteins. B. one fluorescently-tagged protein assigned by their TA. C. two separate runs with two different flourescently-tagged proteins in each run D. A mixture containing three fluorescently-tagged proteins
B. one fluorescently-tagged protein assigned by their TA.
The purpose of the "Wash Buffer", that is run through the column, is... A. to elute your bound protein or proteins of interest from the stationary phase (resin). B. to was out "other", non-bound proteins from the column, leaving behind the bound protein or proteins on the resin stationary phase. C. to condition the resin stationary phase before adding sample. D. to rinse the polyacrylamide gel after running the gel electrophoresis on your sample.
B. to wash out "other", non-bound proteins from the column, leaving behind the bound protein or proteins on the resin stationary phase.
In what order should the plant pigments elute from the C-18 column in today's experiment? (LC) A. chlorophylls → carotenes → xanthophylls B. xanthophylls → chlorophylls → carotenes C. carotenes → chlorophylls → xanthophylls D. xanthophylls → carotenes → chlorophylls
B. xanthophylls, chlorophylls, carotenes (most polar to least polar)
