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

Q: Why do we treat proteins with DTT (or BME) prior to SDS-PAGE?
- To disrupt primary structure
- To break disulfide bonds
- To make the proteins negative
- To enhance stacking
A: To break disulfide bonds

Q: What induces expression of BglA from the pLATE31 plasmid?
- arabinose
- ampicillin
- IPTG
- X-gal
A: arabinose

Q: What is the purpose of chromatography?
- To separate molecules based on affinities to a stationary and mobile phase
- To separate molecules based on molecular weight and three-dimensional shape
- To separate molecules based on negative or positive charges
- To separate molecules based on hydrophobicity of amino acids
A: To separate molecules based on affinities to a stationary and mobile phase

Q: What is the approximate V_max for the enzyme that produced the data below?
- 4.3 uM/sec
- 2 uM
- 4.3 uM
- 2 uM/sec
A: 4.3 uM/sec

Q: What is achieved when enzyme is saturated with substrate?
- V_max
- k_cat
- K_m
- pKa
A: V_max

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: Jesse ran a Bradford assay to determine the concentration of protein in a sample. His standard curve is below. A two-fold dilution of the unknown protein had an absorbance value of 0.80 at 595 nm.

What was the concentration of the original undiluted unknown sample?
- 1533 ug/mL
- 767 ug/mL
- 383 ug/mL
- 0.0343 ug/mL
A: 1533 ug/mL

Q: What does SDS do to proteins?
- It adds negative charges.
- It breaks disulfide bonds.
- It reinforces tertiary structure.
- It neutralizes charge.
A: It adds negative charges.

Q: Which level of protein structure is defined by the order of amino acids?
- Primary structure
- Secondary structure
- Tertiary structure
- Quaternary structure
A: Primary structure

Q: Which level of protein structure includes the overall three-dimensional structure?
- Primary structure
- Secondary structure
- Tertiary structure
- Quaternary structure
A: Tertiary structure

Q: Which type of interaction is responsible for tertiary structure?
- Interactions among atoms on the polypeptide backbone
- Interactions among atoms on the amino acid R groups
- Peptide bonds
- Hydrogen bonds
A: Interactions among atoms on the amino acid R groups

Q: Why don’t all proteins have quaternary structure?
- Some proteins only have one polypeptide chain.
- Some proteins don’t contain cysteines.
- Some proteins have more charged residues than uncharged.
- Some proteins don’t have enough amino acids.
A: Some proteins only have one polypeptide chain.

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

Q: How do charged R groups affect protein structure?
- Their interactions help create tertiary structure.
- Their interactions help create secondary structure.
- They promote binding by chaperones.
- They reinforce peptide bonds in primary structure.
A: Their interactions help create tertiary structure.

Q: Why does denaturation alter protein function?
- Because protein function is dependent on protein shape
- Because proteins function in a narrow range of pH values
- Because proteins function in a narrow range of temperatures
- Because protein function requires the presence of substrate
A: Because protein function is dependent on protein shape

Q: BglA could be used in the production of what biotech product?
- Biofuel
- Laundry detergent
- Soybeans
- Pharmaceuticals
A: Biofuel

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

Q: Which type of chromatography might use beads that are bound to antibodies?
- Size exclusion
- SDS-PAGE
- Affinity
- Ion exchange
A: Affinity

Q: Which type of chromatography might use beads bound to an enzyme’s ligand?
- Size exclusion
- SDS-PAGE
- Affinity
- Ion exchange
A: Affinity

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

Which will come off the column first?
- 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: You are performing ion exchange chromatography with negatively 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 19 kD that is strongly positively charged

Q: You are performing affinity chromatography with beads that are bound to anti-FLAG antibodies.

Which protein will bind to the beads?
- A protein with a FLAG-tag
- A protein without FLAG tags
- The flagellin protein
- Signaling proteins
A: A protein with a FLAG-tag

Q: Which protein would migrate through a non-denaturing gel most rapidly? (The gel is set up with the standard positive-negative polarity.)
- A low MW protein with compact shape and negative charge
- A high MW protein with compact shape and negative charge
- A low MW protein with compact shape and positive charge
- A high MW protein with compact shape and positive charge
A: A low MW protein with compact shape and negative charge

Q: What role do glycine ions play in SDS-PAGE?
- They promote protein stacking.
- They coat the proteins with negative charges.
- They initiate polymerization of the gel.
- They are in the gel to help maintain pH.
A: They promote protein stacking.

Q: Which layer of the SDS-PAGE gel has approximately 4-5% acrylamide?
- Stacking gel
- Separating gel
- Agarose gel
- Analytical gel
A: Stacking gel

Q: What question might be answered using enzyme kinetic studies?
- Under what conditions does my enzyme work most efficiently?
- What is the molecular weight of my enzyme?
- What is the charge of my enzyme?
- Under what conditions does my enzyme replicate?
A: Under what conditions does my enzyme work most efficiently?

Q: If a reaction using 5 mM of enzyme has a V_max
of 25 mM/sec, what is k_cat?
- 5/sec
- 125/sec
- 5 mM/sec
- 125 mM/sec
A: 5/sec

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: You obtained the standard curve below in a Bradford Assay. A two-fold dilution of your sample had a A595 value of 0.8.

What is the concentration of the original unknown sample?
- 17.8 ug/mL
- 8.9 ug/mL
- 4.5 ug/mL
- 0.13 ug/mL
- 0.26 ug/mL
A: 17.8 ug/mL

Q: What is the approximate mass of the target protein on this SDS-PAGE?
- 70 kDa
- 70 bp
- 5 kDa
- 5 bp
A: 70 kDa

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: 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