QBM Exam 2

Which of the following gels would be observed if the tetramer shown below was treated in the presence and absence of B-ME? *charts*

4 lines under M, line at 50 for +B-ME, and line at 200 for -B-ME

Which of the following would elute first from an SEC column with G-60 beads? A) 80 kDa protein. B) 60 kDa protein. C) 35 kDa protein. D) 20 kDa protein. E) 10 mM NaCl.

A) 80 kDa protein.

When a protein is SUMOylated, a SUMO protein covalently attaches to the target protein at a lysine. On the SDS-PAGE gel below, which band, 1 or 2, represents the SUMOylated protein? A) Band 1. B) Band 2.

A) Band 1

Why aren't native gels generally used to determine the molecular weight of proteins? A) Proteins separate by both mass and charge on native gels. B) Proteins separate only by charge on native gels. C) Native gels are very expensive due to the need for ampholytes. D) Native gels require special equipment to be made correctly. E) Native gels never show proteins in their monomeric form.

A) Proteins separate by both mass and charge on native gels.

Which of the following secondary antibodies can be used in conjunction with a goat anti-GST primary antibody to successfully perform a Western Blot? A) Rabbit anti-goat. B) Rabbit anti-GST. C) Goat anti-GST. D) Goat anti-rabbit. E)Sheep anti-rabbit.

A) Rabbit anti-goat.

After expressing MBP-actin and purifying the complex with a maltose column, you cleave the tag (MBP) with a protease. You now have a solution of MBP and actin. What would be the next step logical step? A) Rerun the solution over a maltose column to separate the tag from actin. B) The purification is complete. C) Rerun the solution over a maltose column which will bind actin. D) Rerun the solution over a maltose column and digest the eluent with protease

A) Rerun the solution over a maltose column to separate the tag from actin.

You load three proteins with pIs of 3, 7, and 10 onto an anion exchange column that is equilibrated at pH 4. Which proteins will bind? A) The protein with a pI of 3. B) The protein with a pI of 7. C) The protein with a pI of 10. D) The proteins with a pI of 7 and 10. E) All of the proteins will bind.

A) The protein with a pI of 3.

Which of the following is TRUE about the gel in gel electrophoresis? A) it allows the position of a protein to be retained for further analysis. B) It causes a loss of resolution via vibrational and convectional disturbances. C) It provides zero friction or resistance, so proteins move unimpeded. D) It only allows antibodies to bind.

A) it allows the position of a protein to be retained for further analysis.

Ion exchange chromatography is useful for A) separating proteins based on charge. B) separating proteins based on molecular weight. C) a buffer exchange. D) separating proteins based on hydrophobic interactions. E) concentrating proteins.

A) separating proteins based on charge.

When performing a Western Blot, the primary antibody will bind to the __________, and the secondary antibody will bind to the __________. A) target protein ; Fc region of the primary antibody B) Fc region of the secondary antibody ; target protein C) Fc region of the primary antibody ; target protein D) target protein ; Fc region of the target protein E) constant region of the primary antibody ; target protein

A) target protein ; Fc region of the primary antibody

Which of the following can be used to gently concentrate a protein sample? A)Reverse dialysis. B) DTT. C) Western Transfer. D) NaCl precipitation. E) Heat evaporation.

A)Reverse dialysis.

You are studying a hexamer that consists of a 20 kDa homodimer, a 30 kDa homodimer, and a 40 kDa homodimer. You would see _______ band(s) on a native gel and _______ band(s) on an SDS- PAGE. A) 1;2 B) 1;3 C) 1;6 D) 2;3 E) 3;6

B) 1;3

The gel below shows an induced cell lysate, with the pre-induced (lane 1), insoluble (lane 2), and soluble (lane 3) fractions. What is the molecular weight of the induced protein? A) 14 kDa B) 21 kDa C) 38 kDa D) 43 kDa E) 95 kDa

B) 21 kDa

The following gel of various unrelated proteins was used for a western blot. Based on the system discussed in class, what is the minimal number of different antibodies that had to be used to generate this western blot? Add up all primaries (non-conjugated, 100% specific) and secondaries. A) 2 B) 3 C) 4 D) 6 E) 8

B) 3

GST-GFP fusion protein has a theoretical pI of 5.9, at what pH would this protein have a net charge of 0? A) 4.9 B) 5.9 C) 6.9 D) 0 E) 7

B) 5.9

After running SDS-PAGE, you would like to perform a Western Blot to verify the presence of the protein of interest. Which of the following primary antibodies would bind to the protein with the highest specificity? A) A monoclonal antibody that will target a conformational epitope. B) A monoclonal antibody that will target a linear epitope. C) A polyclonal antibody that will target a conformational epitope. D) A polyclonal antibody that will target a linear epitope.

B) A monoclonal antibody that will target a linear epitope.

In the Ptac expression system, A) the lac repressor protein is bound to the T7 promoter. B) E. coli RNA polymerase transcribes the gene of interest into mRNA. C) T7 RNA polymerase is bound to the T7 promoter. D) the lac repressor protein is bound upstream of the T7 RNA polymerase gene. E) IPTG is bound to the promoter.

B) E. coli RNA polymerase transcribes the gene of interest into mRNA.

Which of the following can be used as a protease inhibitor to prevent protein degradation? A) Chaotropic salts. B) EDTA. C) Propylene glycol. D) Ammonium sulfate. E) TCE.

B) EDTA.

Which of the following techniques would be best to identify protein-protein interactions? A) Western blot. B) Far-western blot. C) Southwestern blot. D) Northern blot. E) Southern blot.

B) Far-western blot.

In cation exchange chromatography, the counter ion is _______, and the column contains beads that are _______ -charged. A) Na+ ; positively B) Na+ ; negatively C) Cl- ; positively D) Cl- ; negatively

B) Na+ ; negatively

Which would be a better choice if you were studying protein-protein interactions or protein modifications? A) SDS-PAGE. B) Native gel electrophoresis. C) Agarose gel electrophoresis. D) Ion exchange chromatography. E) Immunoprecipitation.

B) Native gel electrophoresis.

Why was a gradient of 0 to 100% salt used in the anion exchange chromatography that you performed in the QBM lab? A) Adding 100% salt from the start would clog the column. B) Slowly adding salt will separate unwanted proteins that bound to the column from your protein. C) Adding 100% salt from the start would cause your protein to precipitate on the column. D) Slowly adding salt will elute proteins with the most negative charge first, before GST

B) Slowly adding salt will separate unwanted proteins that bound to the column from your protein.

The gel below shows an SDS-PAGE gel run under various conditions (harsh and mild) to study a protein's oligomeric state. Use this gel to determine the protein's structure. A) The protein forms an octamer, consisting of four dimers, each of which is held together by disulfide bonds B) The protein forms a hexameter, consisting of two trimers, each of which is held together by disulfide bonds. C) The protein forms a hexamer, consisting of three dimers, each of which is held together by disulfide bonds D) The protein forms an octamer, consisting of four dimers, each of which is held together by ionic interactions E) The protein forms an octamer, consisting of two dimers, each of which is held together by disulfide bonds

B) The protein forms a hexameter, consisting of two trimers, each of which is held together by disulfide bonds.

A tetramer with subunits connected only by disulfide bridges runs through an SEC column and elutes in Fraction 20. After 100% successful treatment with DTT the protein is rerun over the same column. Which of the following is TRUE? A) The protein will elute in Fraction 20. B) The protein will elute later (i.e. Fraction 30). C) The protein will elute earlier (i.e. Fraction 10). D) The protein will bind irreversibly to the column.

B) The protein will elute later (i.e. Fraction 30).

What type of chromatography would you use to separate the ink from a line you've drawn on a piece of paper, or check the purity of an organic compound? A) Low pressure liquid chromatography. B) Thin layer chromatography. C) High performance liquid chromatography. D) Adsorption chromatography. E) Size exclusion chromatography.

B) Thin layer chromatography.

SDS-PAGE requires the detergent sodium dodecyl sulfate to be added to the sample because it A) neutralizes DNA's negatively-charged backbone which can prevent migration through a gel. B) coats proteins in a negative charge, allowing them to migrate according to size. C) makes the gel more hydrophobic, reducing interactions with proteins and DNA. D) helps molecules to retain their tertiary structure in the harsh electrical current. E) allows proteins to be separated on differences in their charge-to-mass ratios

B) coats proteins in a negative charge, allowing them to migrate according to size.

HaloTag-p53 is cleaved from a column using a His-tagged protease. This collected sample now contains both p53 and the protease. Passing this sample over a nickel column will result in the p53 to be A) bound to the nickel column. B) collected in the flowthrough fractions. C) collected in the elution fractions. D) bound to histidine. E) bound to the HaloTag.

B) collected in the flowthrough fractions.

To search for proteins that bind DNA you would use a(n) A) northwestern blot. B) electrophoretic mobility shift assay. C) far-western blot. D) western blot.

B) electrophoretic mobility shift assay.

In lab, GST was eluted from the affinity column using A) sodium chloride. B) glutathione. C) glutathione-S-transferase. D) CDNB. E) imidazole.

B) glutathione.

Adding proteases to a purified protein can help you to determine A) dissociation constants. B) if the protein has different conformational states under different conditions. C)if the purification was successful. D) whether antibodies can be generated to the protein's peptides. E) the free energy of binding.

B) if the protein has different conformational states under different conditions.

N-terminal sequencing A) can be performed on impure samples. B) is limited to ~50 amino acids. C) involves digesting a protein with proteases and analyzing it via mass spectrometry. D) is also known as mass spectrometry sequencing.

B) is limited to ~50 amino acids.

Cation exchangers bind to _____ -charged proteins, and anion exchangers bind to _____ -charged proteins. A) positively ; positively B) positively ; negatively C) negatively ; positively D) negatively ; negatively

B) positively ; negatively

You express a his-tagged protein in E. coli, lyse the cells, spin them down, and perform a western blot using an anti-his antibody. After seeing the results of the western blot below, you decide that your next step should be to A) purify the protein with metal chelate chromatography. B) refold the insoluble fraction using guanidine. C) give up on using E. coli since the protein was not expressed, and instead switch to a yeast- based expression system. D) purify the protein with immunoprecipitation using the anti-his antibody and agarose capture beads. E) re-express the cells at 42 °C overnight.

B) refold the insoluble fraction using guanidine.

The figure below shows MEF2C-SUMO present in lanes 1 and 3, but not in lanes 2 or 4. This demonstrates that A) the arginine (R) at position 391 is essential to sumoylation. B) the serine (S) at 396 can be mimicked by a glutamate (E). C) the alanine (A) at 396 can be mimicked by a serine (S). D) the alanine (A) at position 396 is essential to sumoylation. E) an alignment of the MEF2 family of proteins would show a conserved arginine at position 396.

B) the serine (S) at 396 can be mimicked by a glutamate (E).

Based on the gel shown below, the protein of interest likely has __________ domains. A) 1 B) 2 C) 3 D) 4 E) 5

C) 3

Which of the following can be used to precipitate a protein of interest in a controlled manner? A) Chaotropic salts. B) Triton X-100. C) Ammonium sulfate. D) EDTA. E) Dialysis.

C) Ammonium sulfate.

Which of the following best characterizes ion exchange chromatography? A) Proteins in a buffer with a pH equal to their pI will bind to an ion exchange column. B) Charged proteins attach to a neutral solid phase and are eluted with a charged counterion. C) Charged proteins attach to an oppositely-charged ion bound to a solid phase and are eluted with a charged counterion. D) Charged proteins attach to an oppositely-charged ion bound to a solid phase and are eluted with an uncharged solvent.

C) Charged proteins attach to an oppositely-charged ion bound to a solid phase and are eluted with a charged counterion.

The image below shows the same proteins run on three different gels for the same length of time with the same current. Which gel contains the highest percentage of acrylamide? A) Gel A. B) Gel B. C) Gel C. D) All three gels are equal.

C) Gel C

Which of the following techniques would be best to separate proteins based on pI? A) Native gel electrophoresis. B) SDS-PAGE. C) Isoelectric focusing. D) Size exclusion chromatography. E) Co-immunoprecipitation.

C) Isoelectric focusing.

What will occur if the blocking step is omitted during the Western Blotting procedure? A) The primary antibody will only bind to the nitrocellulose membrane. B) The primary antibody will bind only to the target protein. C) The primary antibody will bind to the target protein and the nitrocellulose membrane. D) The secondary antibody will only bind to the target protein.

C) The primary antibody will bind to the target protein and the nitrocellulose membrane.

You are using an anti-mouse monoclonal antibody to a nonlinear conformational epitope in an ELISA. Which of the following is TRUE? A) This antibody should work well in a western blot from an SDS-PAGE gel. B) This antibody can't be used in a western blot because it will be denatured by the residualSDS. C) This antibody can be useful in targeting a protein blotted from a native gel. D) This antibody should have higher affinity than a polyclonal antibody. E) This antibody will target only human proteins.

C) This antibody can be useful in targeting a protein blotted from a native gel.

What is the purpose of adding sodium azide (NaN3) to a protein sample? A) To act as a cryoprotectant. B) To reduce carboxyl groups. C) To prevent microorganism growth. D) To inhibit proteases. E) To act as a buffer against changes in pH that fall outside of the range of Tris.

C) To prevent microorganism growth.

Prior to running your sample in isoelectric focusing, you must add A) SDS. B) amphipathics. C) ampholytes. D) glycogen. E) All of the answer choices are correct.

C) ampholytes.

The diagram below shows A) size exclusion chromatography. B) anion exchange chromatography. C) cation exchange chromatography. D) hydrophobic interaction chromatography. E) affinity chromatography.

C) cation exchange chromatography.

2D gel electrophoresis is ___________ in the first dimension and ____________ in the second dimension. A) SDS-PAGE ; isoelectric focusing B) native gel electrophoresis ; isoelectric focusing C) isoelectric focusing ; SDS-PAGE D) isoelectric focusing ; native gel electrophoresis E) SDS-PAGE ; Western Blotting

C) isoelectric focusing ; SDS-PAGE

Size exclusion chromatography is useful for all of the following EXCEPT A) separating aggregates or oligomers from monomers. B) separating molecules based on molecular weight. C) separating molecules based on affinity to the beads. D) a buffer exchange.

C) separating molecules based on affinity to the beads.

A technique that allows you to determine the thermodynamics of protein binding is A) the yeast two-hybrid assay. B) southwestern blotting. C) surface plasmon resonance. D) far-western blot. E) EMSA.

C) surface plasmon resonance.

You place a 20 kDa protein and a 50 kDa protein in a dialysis tubing that has a 30 kDa cutoff, and place it in a beaker with buffer. If these proteins do not interact, A) both proteins will remain inside of the dialysis tube. B) the 50 kDa protein will equilibrate with the buffer. C) the 20 kDa protein will equilibrate with the buffer. D) both proteins will equilibrate with the buffer.

C) the 20 kDa protein will equilibrate with the buffer.

You load a lysate sample containing a 20 kDa protein and a 70 kDa protein onto a size exclusion chromatography column which produces the chromatogram shown below. Based on the chromatogram, you would expect A) the 70 kDa protein to be found primarily in the second peak. B) the 20 kDa protein to be found primarily in the first peak. C) the 70 kDa protein to be found primarily in the first peak. D) the 20 kDa protein to be evenly distributed in both peaks. E) the 70 kDa protein to be evenly distributed in both peaks.

C) the 70 kDa protein to be found primarily in the first peak.

In western blotting, the blocking step is essential to ensure A) the antibody binds to the membrane. B) the primary and secondary antibody interact correctly. C) the antibody binds only to the protein of interest. D) the conjugated enzyme functions correctly. E) the TBS-T will not pull the antibody off of the protein of interest.

C) the antibody binds only to the protein of interest.

61. Based on the gel below, you can conclude that A) the tyrosine (Y) at position 37 is essential for ubiquitination. B) the alanine (A) at position 200 is essential for ubiquitination. C) the lysine (K) at position 200 is essential for ubiquitination. D) the L504A mutation causes an increase in ubiquitination.

C) the lysine (K) at position 200 is essential for ubiquitination.

You wish to use dialysis to determine if a 30 kDa and 40 kDa protein interact. You should mix both proteins and place them into dialysis tubing with a ________ kDa cutoff, and test to see if a dimer remains inside the tubing. A) 25 B) 30 C) 35 D) 50 E) 75

D) 50

Which of the following CANNOT be used to identify which fractions from a column contain protein? A) Bradford assay. B) SDS-PAGE. C) A chromatogram. D) A260. E) Enzyme assay.

D) A260.

The newest systems for protein production involve a ribosome and RNA. What are some current limitations to this technique? A) The kits are expensive. B) The protocols are not widely standardized or mastered. C) The yield is low compared to bacterial expression systems. D) All answer choices are correct.

D) All answer choices are correct.

The tracking dye can be used to A) allow gels with different band migrations to be compared via relative mobility. B) allow you to visibly see your sample as you pipette it into the well. C) prevent proteins from running off the bottom of the gel by letting you know when the gel should be stopped. D) All answer choices are correct.

D) All answer choices are correct.

Which of the following can be used to refold inclusion bodies? A) Guanidine-HCl. B) Urea. C) Chaotropic salts. D) All of the answer choices are correct

D) All of the answer choices are correct

The yeast two-hybrid assay is advantageous because entire gene libraries can be screened to seek out new binding partners to a protein. To accomplish this, A) yeast cells are screened for color changes upon bait/prey interaction. B) genes of the library are inserted into special plasmids that contain activating or binding domains. C) the bait and prey must interact, which allows RNA polymerase to initiate transcription of the reporter. D) All of the answer choices are correct.

D) All of the answer choices are correct.

Which of the following will affect the migration of a protein on a SDS-PAGE gel? A) The ability of SDS to bind to the protein. B) The proline content of the protein. C) Proteins with a large number of positively-charged amino acids. D) All of the answer choices are correct.

D) All of the answer choices are correct.

Freezing/thawing cycles may denature proteins in a sample. This can be mitigated by the use of all of the following EXCEPT A) glycerol. B) ethylene glycol. C) propylene glycol. D) EDTA

D) EDTA

Which of the following chromatography techniques would be best to purify a protein from a lysate sample? A) Thin layer chromatography. B) Gas chromatography. C) High performance liquid chromatography. D) Low pressure liquid chromatography. E) Ammonium sulfate precipitation.

D) Low pressure liquid chromatography.

Which of the following can be used as a membrane to bind proteins in western blotting? A) PVDF. B) Nitrocellulose. C) Blotting paper. D) PVDF or nitrocellulose. E) Nitrocellulose or blotting paper.

D) PVDF or nitrocellulose.

Why are certain lines of E. coli (like BL21) used for protein expression? A) They express lon and ompT proteases. B) They contain the β-galactosidase gene on their genome. C) They contain an ampicillin resistance gene on their genome. D) They contain the T7 RNA polymerase gene on their genome. E) They can outcompete wild-type E. coli.

D) They contain the T7 RNA polymerase gene on their genome.

Which of the following is TRUE regarding the ammonium sulfate cut? A) The technique is too expensive compared to newer techniques. B) You can use it to tag proteins for purification. C) It is frequently used to obtain large amounts of human proteins. D) You can isolate new proteins in their native form.

D) You can isolate new proteins in their native form.

In the picture below, A) the FLAG domain is responsible for protein dimerization. B) an alanine at position 571 is required for protein dimerization. C) the monomer is the wild-type conformation of the protein. D) a native gel is shown. E) BchE's FLAG domain was mutated at position 571.

D) a native gel is shown.

A protein that can be acetylated has five domains (A through E, shown below). A study of these domains is shown in the western blot of an SDS-PAGE below. From this data you can conclude that A) domain E is essential to acetylation by process of elimination. B) domains C and D are essential to acetylation. C) β-actin is essential to acetylation. D) domains A and B are essential to acetylation. E) the data is not usable due to variability in the loading control between lanes.

D) domains A and B are essential to acetylation.

Proteins can be located in fractions from a column using A) the chromatogram. B) SDS-PAGE. C) its biological activity. D) the Bradford Assay. E) All of the answer choices are correct.

E) All of the answer choices are correct.

Which of the following techniques can be used to study DNA-protein interactions? A) DNA footprinting. B) Chromatin immunoprecipitation. C) Electrophoretic mobility shift assay. D)Southwestern Blot. E) All of the answer choices are correct.

E) All of the answer choices are correct.

Which of the following CANNOT be used to lyse cells to yield stable protein? A) Detergents B) Enzymes C) Pressure D) Sonication E) Heat

E) Heat

A his-tagged protein can be purified using magnetic beads. How does this compare to chromatography? A) Magnetic beads are faster than chromatography and produce more pure protein. B) Magnetic beads are slower and more expensive than chromatography, but produce more pure protein. C) Magnetic beads are slower than chromatography and produce less pure protein. D) Magnetic beads are too complicated for day-to-day use in the laboratory. E) Magnetic beads are faster than chromatography, but produce less pure protein.

E) Magnetic beads are faster than chromatography, but produce less pure protein.

Which of the following CANNOT be used to produce a 500 amino acid protein? A) In vitro systems. B) E. coli. C) insect cells. D) Plant cells. E) Organic synthesis.

E) Organic synthesis.

Which of the following ways could NOT be used to concentrate 100 ml of a his-tagged protein to 5 ml? A) Running it on a nickel column and eluting the protein in 5 ml. B) Nitrogen pressure and a stirred cell concentration down to 5 ml. C) Spin down to 5 ml on spin columns in a centrifuge. D) Dialysis tubing surrounded by PEG to dehydrate the sample down to 5 ml. E) Precipitating the protein in high salt (NaCl) and redissolving it in 5 ml.

E) Precipitating the protein in high salt (NaCl) and redissolving it in 5 ml.

You analyze a protein of interest (below) for expression in E. coli and use β-actin as a loading control to compare samples. What can you conclude from this gel? A) The same amount of protein was loaded into every lane. B) Sample 5 has much higher expression than Sample 2. C) You missed the well when loading Sample 3 and it all went into the buffer. D) Sample 1 has higher expression than Sample 5. E) There were pipetting errors when loading these samples on this gel.

E) There were pipetting errors when loading these samples on this gel.

After performing column chromatography, you run the fractions on a gel as shown below. If you wanted to maximize the amount of your target protein, which fractions should you keep? A) 1,2,and3. B) 2,3,and4. C) 1and2. D) 3. E) 6,7,and8.

NOT A

Which of the following techniques can be used to identify the specific DNA sequence with which a protein interacts? A) Western blot. B) Edman degradation. C) Yeast two-hybrid assay. D) Far western blot. E) DNA footprinting.

NOT A

Which of the following would travel the furthest down a native gel? A) A large protein with a low negative charge. B) A large protein with a high negative charge. C) A small protein with a low negative charge. D) A small protein with a high negative charge.

NOT A

A major disadvantage to the enzyme-linked immunosorbent assay is that A) it is a very time consuming to perform. B) it is not practical in the medical field. C) it can only be used to screen one sample at a time. D) it gives no information on the molecular weight of the antigen.

NOT A or B

What conclusions can be drawn based on the EMSA results shown below? A) Protein 2 interacts with the DNA fragment. B) Protein 2 does not interact with the DNA fragment. C) Protein 1 interacts with the DNA fragment. D) Protein 1 and 2 interact with the DNA fragment. E) Protein 1 and 2 do not interact with the DNA fragment.

NOT B

You are studying a heterotrimer that is held together by disulfide bonds. In the absence of -ME (in either the native or SDS-PAGE), you would see __________ band(s) on a native gel and __________ band(s) on SDS-PAGE. A) 1;1 B) 1;3 C) 3;1 D) 3;3

NOT B

The image below best represents A) a direct ELISA. B) an indirect ELISA. C) a pregnancy test. D) a Western Blot. E) an EMSA.

NOT B or A (try EMSA)

Based on the native gel shown below, what is the oligomeric state of the protein? A) Monomer. B)Dimer. C) Trimer. D) Tetramer. E) Pentamer.

NOT B or C

When analyzing a protein that forms an octamer, the addition of heat will disrupt which of the following? A) Weak interactions. B) Disulfide bridges. C) Peptide bonds. D) Covalent bonds. E) Partial double bonds

NOT B or C

Protein X is a multimer. You make a fusion protein X-GST to study this interaction (as shown below). You mix protein X and X-GST and run the samples on a native gel and see 5 bands. From this you can conclude that protein X forms A) monomers. B) dimers. C) trimers. D) tetramers. E) pentamers.

NOT C

The image below shows a native gel with various oligomers. How many bands would appear if the same homodimer shown was loaded onto an SDS-PAGE gel? A) 1 B) 2 C) 3 D) 4 E) 5

NOT C

Sodium dodecyl sulfate is used to A) disrupt the disulfide bridges that exist in the tertiary structure. B) coat proteins with a negative charge. C) maintain proteins in their native state. D) break covalent bonds that are present between amino acids. E) weigh the sample down in the gel well

NOT D

In order to increase resolution, researchers may use 3D gel electrophoresis where proteins are first run on __________, followed by __________, and then __________. A) SDS-PAGE ; isoelectric focusing ; native gel electrophoresis B) native gel electrophoresis ; isoelectric focusing ; SDS-PAGE C) native gel electrophoresis ; SDS-PAGE ; isoelectric focusing D) affinity chromatography ; SDS-PAGE ; western blotting E) affinity chromatography ; isoelectric focusing ; SDS-PAGE

NOT D or A

In the gel below, the protein of interest is shown in bold. Which of the following statements best describes this protein? A) The protein of interest is positively charged in the IEX elution. B) The protein of interest can be found in the soluble fraction. C) Chaotropic salts were used to solubilize the protein prior to IEX chromatography. D) The protein of interest is approximately 26 kDa. E) The final product after chromatography is 100% pure

NOT E

GST can be purified from a lysate sample using either anion or cation exchange chromatography. true/false

TRUE

Why might a researcher opt to use native gel electrophoresis? A) To separate proteins based solely on molecular weight. B) To determine the oligomeric state of a protein. C) To allow for the separation of proteins based on charge alone. D) To analyze proteins in their linear conformations. E) To run a sample under denaturing conditions

not C or A

Which of the following can be concluded from the gel shown below? A) The unglycosylated protein has a mass of approximately 53 kDa. B) The molecular weight of one sugar is approximately 2 kDa. C) The molecular weight of two sugars is approximately 56 kDa. (NOT RIGHT) D) The protein with four sugars would have a mass of approximately 62 kDa. E) The sugars are causing the protein to denature, and thus run slower on the gel.

not c