Title: Final Exam Form B
Course: BTEC-2020-301-302-303-F21 > Section: Final Project and Exam

Q: Which level of protein structure includes alpha helices and beta sheets?
- Primary structure
- Secondary structure
- Tertiary structure
- Quaternary structure
A: Secondary structure

Q: Which type of interaction is responsible for formation of alpha helices?
- Interactions among atoms on the polypeptide backbone
- Interactions among atoms on the amino acid R groups
- Hydrophobic interactions
- Ionic interactions
A: Interactions among atoms on the polypeptide backbone

Q: What type of strong bond can only be formed between two cysteine R groups?
- Disulfide bond
- Hydrogen bond
- Ionic bond
- Peptide bond
A: Disulfide bond

Q: Which type of chromatography uses beads with strong negative or positive charges?
- Size exclusion
- SDS-PAGE
- Affinity
- Ion exchange
A: Ion exchange

Q: If a reaction using 2 mM of enzyme has a V_max
of 30 mM/sec, what is k_cat?
- 15/sec
- 60/sec
- 15 mM/sec
- 60 mM/sec
A: 15/sec

Q: You are using size exclusion chromatography to separate the following molecules.

Which will come off the column last?
- A protein of 85 kD that is strongly negatively charged
- A protein of 57 kD that is slightly positively charged
- A protein of 42 kD that is slightly negatively charged
- A protein of 19 kD that is strongly positively charged
A: A protein of 19 kD that is strongly positively charged

Q: You are performing ion exchange chromatography with positively charged beads in the column.

Which protein would elute last?
- A protein of 85 kD that is strongly negatively charged
- A protein of 57 kD that is slightly positively charged
- A protein of 42 kD that is slightly negatively charged
- A protein of 19 kD that is strongly positively charged
A: A protein of 85 kD that is strongly negatively charged

Q: Which statement accurately describes separation of proteins in a non-denaturing gel?
- Protein migration is unpredictable.
- Smaller proteins migrate fastest.
- Proteins with negative charges migrate slowest.
- Protein migration is determined by voltage.
A: Protein migration is unpredictable.

Q: Under what conditions would V_max
theoretically be achieved?
- Infinite substrate
- Infinite enzyme
- At the optimal temperature
- At the optimal pH
A: Infinite substrate

Q: What indicates that an enzyme inhibitor binds at an allosteric site?
- The inhibitor has no effect on k_cat.
- The inhibitor increases k_cat.
- The inhibitor decreases k_cat.
A: The inhibitor decreases k_cat.

Q: What is the approximate mass of the protein in lane 4?
- 65 kDa
- 65 bp
- 4 kDa
- 4 bp
A: 65 kDa

Q: Which layer of the SDS-PAGE gel usually has 10-15% acrylamide?
- Stacking gel
- Separating gel
- Agarose gel
- Analytical gel
A: Separating gel

Q: You are performing affinity chromatography with nickel beads.

When would selective elution of a his-tagged protein occur?
- After application of a buffer with imidazole
- After application of a buffer with IPTG
- After application of a buffer with high pH
- After application of a buffer with proteases
A: After application of a buffer with imidazole

Q: You are using a nickel column to purify a his-tagged protein.

On the graph below, which peak represents the his-tagged protein?
- A
- B
- C
A: B

Q: What does SDS do to proteins?
- It adds positive charges.
- It breaks disulfide bonds.
- It makes proteins rod-shaped.
- It neutralizes charge.
A: It makes proteins rod-shaped.

Q: What is the purpose of boiling proteins before SDS-PAGE?
- It denatures proteins.
- It neutralizes protein charges.
- It makes proteins more compact.
- It makes proteins negatively charged.
A: It denatures proteins.

Q: Which level of protein structure arises when multiple protein subunits come together?
- Primary structure
- Secondary structure
- Tertiary structure
- Quaternary structure
A: Quaternary structure

Q: What is denaturation?
- Loss of functional shape
- Change in amino acid sequence
- Change in DNA sequence
- Formation of multi-subunit complexes
A: Loss of functional shape

Q: In a globular protein, where are hydrophobic side chains most likely to be found?
- In the core of the protein
- On the surface of the protein
- Forming bonds with hydrophilic side chains
- Forming bonds with cysteine side chains
A: In the core of the protein

Q: Why does denaturation alter protein function?
- Protein function is dependent on protein shape.
- Peptide bonds required for function are broken.
- The release of chaperones disrupts function.
- Disulfide bonds disrupt function.
A: Protein function is dependent on protein shape.

Q: What chemical is used in the lab to induce expression from the lac operon?
- IPTG
- arabinose
- X-gal
- lactase
A: IPTG

Q: The modern biotechnology industry got its start with the expression and purification of what molecule?
- insulin
- human growth factor
- green fluorescent protein
- BglA
A: insulin

Q: Which method of cell lysis uses high pressure?
- Sonication
- Lysozyme
- French press
- Bead beating
A: French press

Q: What is the general definition of chromatography?
- Separation of molecules based on affinities for mobile and stationary phases.
- Separation of molecules based whether the fit inside tiny pores.
- Separation of molecules based on whether they bind to negative charges.
- Separation of molecules based on whether they bind to antibodies.
A: Separation of molecules based on affinities for mobile and stationary phases.

Q: What would happen in SDS-PAGE if both layers of the gel were made with the same pH?
- Stacking would not occur properly.
- The gel would run more slowly.
- The proteins would migrate up rather than down.
- The gel would melt at high voltage.
A: Stacking would not occur properly.

Q: Which type of chromatography uses beads with pores of varying sizes?
- Size exclusion
- SDS-PAGE
- Affinity
- Ion exchange
A: Size exclusion

Q: What question might be answered using enzyme kinetic studies?
- Does an inhibitor bind at the enzyme active site?
- What is the affinity of an antibody for the enzyme?
- Was a recombinant enzyme expressed after induction?
- Is the enzyme positively or negatively charged?
A: Does an inhibitor bind at the enzyme active site?

Q: What indicates that an enzyme inhibitor binds at the active site?
- The inhibitor has no effect on k_cat.
- The inhibitor increases k_cat.
- The inhibitor decreases k_cat.
A: The inhibitor has no effect on k_cat.

Q: The image below shows an ion exchange profile with the peaks labeled. The column contains beads that are negatively charged.

Which peak represents the purified protein with the most positive charges?
- A
- B
- C
- D
- E
- F
A: D

Q: What is the approximate V_max for the enzyme that produced the data below?
- 12.5 uM/sec
- 12.5 uM
- 10 uM/sec
- 10 uM
A: 12.5 uM/sec

Q: You obtained the standard curve below in a Bradford Assay. A two-fold dilution of your sample had an A595 value of 0.7.

What is the concentration of the original unknown sample?
- 0.88 mg/mL
- 0.44 mg/mL
- 0.22 mg/mL
- 1.1 mg/mL
- 2.2 mg/mL
A: 0.88 mg/mL

Q: A new employee at your company is running a Bradford Assay to determine the concentration of a protein sample. The standard curve she obtained is below. The unknown sample had an A595 value of 0.6.

What is the approximate concentration of the unknown sample?
- 0.38 mg/mL
- 0.94 mg/mL
- 1.5 mg/mL
- 0.03 mg/mL
A: 0.38 mg/mL