BIOL 2083 Tophat questions Quiz 1
The yield parameter increases with each purification step. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
F
You have the following mixture of proteins:a. 40 kDa protein, pI 6.3b. a dimer of 20 kDa subunits, pI 8.2c. a tetramer of 10 kDa subunits, pI 4.1d. 40 kDa protein, pI 6.3, binds to nickel ionsWhich of the following techniques is most useful for separating protein B?
ION EXCHANGE CHROMATOGRPHY
electrostatic
NaCl
What is the charge on the side chain of the amino acid isoleucine at neutral pH? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a positive b negative c neutral
c
What reagent is used to reduce disulfide bonds? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a urea b SDS c beta-mercaptoethanol d none of the above
c
When a protein with a pI of 4.5 is in a buffer with pH 7.4, what is the overall charge on the protein? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a positive b neutral c negative d there is not enough information to determine the charge
c
Which amino acid is found every third residue in the collagen amino acid sequence? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a alanine b tryptophan c glycine d hydroxyglycine
c
Which amino acid is most likely to be buried in the interior of a protein? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a aspartate b lysine c valine d glutamate
c
Which of the following amino acids has a side chain with a basic pKa value? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a alanine b asparagine c lysine d serine
c
Which of the following amino acids has a thioether in its side chain? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a cysteine b isoleucine c methionine d tyrosine
c
All cysteine residues in proteins must participate in disulfide bonds. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
f
Which amino acid can form disulfide bonds?
cystein
Salting out with ammonium sulfate will separate proteins based on their native molecular weight. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
f
During the Anfinsen experiment, ribonuclease structure was directly observed. T or F
false
What is the only achiral amino acid?
glycine
SIDS-PAGE
denatured size
western blot
detection by a specific antibody
What technique allows proteins to be separated from small molecules and ions through a semipermeable membrane?
dialysis
A western blot allows for the specific detection of small amounts of a protein as well as the ability to determine the denatured size of the protein. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
T
In differential centrifugation, if a mixture is spun relatively longer and faster, then smaller components end up in the pellet. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
T
T or F: Water is a polar molecule with a negatively charged oxygen and positively charged hydrogens.
T
The folded state of the protein is its lowest energy state. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
a
Water molecules can be both a hydrogen bond donor and acceptor. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
a
What is the molecular basis of scurvy? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a A deficiency in vitamin C that prevents conversion of proline to hydroxyproline in collagen. b A deficiency in vitamin D that prevents conversion of proline to hydroxyproline in collagen. c A deficiency in vitamin C that prevents conversion of proline to hydroxyproline in keratin. d A deficiency in vitamin C that prevents conversion of glycine to hydroxyglycine in keratin.
a
Which of the following amino acids has a carboxyl group in its side chain? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a glutamate b glutamine c asparagine d threonine
a
A large magnitude of electrostatic energy must mean an attractive force exists between the two ions. a True b False
b
Both alpha helices and beta sheets are stabilized by regular hydrogen bonding between side chain residues in the peptide. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
b
Due to steric clashes between side chain atoms, the peptide bond is normally found in which conformation? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a cis b trans
b
For van der Waals interactions, the energy of the interaction, always increases as the distance between them decreases. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
b
HEPES buffer has a pK of 7.5. Which of the following is true of HEPES at pH 5.5? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a It is completely deprotonated. b It is completely protonated. c It is a mixture of protonated and deprotonated forms.
b
If an ionizable group is protonated, it must also be positively charged. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
b
If two oppositely charged ions are moved further away from one another, what is the effect on the energy of the electrostatic interaction between them? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a It will be a larger negative value b It will be a smaller negative value c The electrostatic energy value changes sign from negative to positive d There is no effect on the electrostatic energy
b
MES buffer has a pKa of 6.1. Which of the following is true of MES at pH 7.5? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a It is completely protonated. b It is completely deprotonated. c It is a mixture of protonated and deprotonated forms.
b
Ramachandran diagrams show all possible rotation angles about the peptide bond. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
b
This technique can be used to track enzyme activity during a purification procedure. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a ELISA b Assay c Western blot d protein concentration
b
What is the charge on the side chain of aspartate at pH 7? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a positive b negative c neutral
b
What is the ratio of enzyme activity relative to total protein? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a yield b specific activity c fold purification d initial velocity
b
What is the role of SDS in SDS-PAGE? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a SDS reduces the disulfide bonds b SDS gives all of the proteins a uniform negative charge c SDS stains proteins for visualization d SDS gives all of the proteins a uniform positive charge
b
affinity chromatography
binding to a specific molecule
Cysteine residue 22 from chain A and cysteine residue 14 from chain B form a disulfide bond in bovine insulin
quaaternary
hydrophobic effect
protein folding
x-ray crystallography
3D structure
Rank the following proteins by their order of elution (first to last) from a gel filtration column.
A trimer of 40 kDa subunits with pI = 5.4 A tetramer of 20 kDa subunits with pI = 8.6 A 60 kDa monomer with pI = 7.6 A dimer of 25 kDa subunits with pI = 8.3 A tetramer of 10 kDa subunits with pI = 4.4 A 20kDa monomer with pI = 9.1
The molecular movement driven by environmental energy is...
Brownian motion
a. 40 kDa protein, pI 6.3b. a dimer of 20 kDa subunits, pI 8.2c. a tetramer of 10 kDa subunits, pI 4.1d. 40 kDa protein, pI 6.3, binds to nickel ionsWhich of the following techniques is most useful for separating protein D? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a Gel filtration chromatography b Ion exchange chromatography c Affnity chromatography d Dialysis
C
Hydrogen bonding
DNA base-pairing
-The buffer Tris (pKa = 8.1) is a good buffer to maintain the pH of a solution at pH 7.5 Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
a
For an Asp to Asn mutation within a protein, which best describes the physical property that has changed? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a A negatively charged amino acid has been substituted with a hydrophilic amino acid. b A positively charged amino acid has been substituted with a hydrophilic amino acid. c A negatively charged amino acid has been substituted with a hydrophobic amino acid. d A hydrophilic amino acid has been substituted with a negatively charged amino acid.
a
If two oppositely charged ions are moved from an aqueous solution to an isopropanol solution (D = 20), what will be the effect on the electrostatic energy between the two ions? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a It will be a larger negative value b It will be a smaller negative value c The electrostatic energy will become positive d There will be no effect on the electrostatic energy value
a
In beta sheets, the side chains of residues stick out perpendicular to the peptide backbone. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
a
Keratin and myoglobin both have alpha-helical secondary structure. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
a
The amino acid sequence of a protein determines its 3D structure. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b
a
The amino terminus of a protein is always positively charged at pH 7. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
a
Which of the following is an aromatic amino acid? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a tryptophan b histidine c proline d glycine
a
Serine, threonine and tyrosine all have what common functional group in their side chain?
alcohol
For a gly to trp mutation in a protein, which of the following best describes the change in physical properties? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a A hydrophilic amino acid has been substituted with a hydrophobic amino acid. b A hydrophobic amino acid has been substituted with a charged amino acid. c A small amino acid has been substituted with a large amino acid. d A charged amino acid has been substituted with a hydrophobic amino acid.
c
This parameter of a protein is the pH at which its net charge is zero. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a denatured molecular weight b Km c pI d native molecular weight
c
Which of the following best describes the energetic basis for the hydrophobic effect when lipids form membrane bilayers in aqueous solution? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a Entropy increases because the lipids are more organized upon bilayer formation. b Entropy decreases because the lipids are more organized upon bilayer formation. c Entropy increases because water molecules are released upon bilayer formation. d Entropy decreases because the water molecules are more ordered around the lipid bilayer.
c
Which of the following best describes the hydrogen bonding pattern for alpha helices? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a i, i+2 b i, i+3 c i, i+4 d i, i+5
c
Which of the following would be the best technique for separating nuclei from cytosolic proteins? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a SDS-PAGE b Gel filtration c Differential centrifugation d Salting out
c
What is the molecular basis of epidermiolysis bullosa simplex (EBS)? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a A mutation in a critical glycine residue in collagen. b A mutation in a critical glycine residue in keratin. c A mutation that disrupts the polyproline cable in keratin. d A mutation that disrupts the coiled coil of keratin.
d
What is the three-letter abbreviation for phenylalanine? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a phy b phn c phl d phe
d
Which amino acid would interact in an electrostatic interaction with the side chain of arginine? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a histidine b proline c glutamine d glutamate
d
Which of the following amino acids has a positively charged side chain at neutral pH? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a threonine b serine c glutamine d lysine
d
Which of the following amino acids is considered hydrophobic? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a phenylalanine b alanine c leucine d all of the above
d
Which of the following is a characteristic of water? a Only in its solid form do molecules participate in H-bonds. b For it's low molecular weight, it's boiling point is also very low. c It's high heat capacity means that it will change temperature rapidly because of the many H-bonds formed between molecules. d None of the above
d
Which of the following is the most conservative mutation? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a Lys to Asp b Trp to Ala c Gly to Pro d Ser to Thr
d
Which of the following is true of anti-parallel beta sheets? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a The strands must come from different polypeptide chains. b The strands are oriented in the same direction with respect to their N and C termini c The strands are more extended relative to parallel beta sheets. d None of the above
d
van der Waals
gecko feet nano hairs and any surface
ion exchange chromatography
native charge
gel filtration chromatography
native size
Which of the following is typically a H-bond acceptor? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. carbon nitrogen calcium hydrogen
nitrogen
western blot
presence of a particular protein
Proline is residue 16 of collagen. primary
primary
mass spectrometry
primary structure
Which amino acid has a side chain that covalently bonds back to the nitrogen of the amino group in the peptide bond?
proline
Residues 12 - 24 of the K channel form a transmembrane alpha helix
secondary
At neutral pH, all amino acids are zwitterionic. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
t
Molecules can have multiple ionizable groups, each with distinct pKa values. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False Submitted:
t
Not all proteins contain quaternary structure. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True Your answer b False
t
Proline is not found in alpha helices because its side chain eliminates the necessary hydrogen bond donor. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
t
The electrostatic energy for two ions of the same charge must be a positive value. Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a True b False
t
Aspartate residue 54 and lysine residue 93 form a salt bridge within the protein myoglobin
tertiary
Cysteine residues 15 and 57 form a disulfide bond in the protein lysozyme
tertiary
Rank the following weak interactions from strongest to weakest in terms of energy (kcal/mol).
two oppositely charged ions in a vacuum -a hydrogen bond between a water molecule and a carbon oxygen - van der Waals interactions between two carbons of adjacent lipid tail groups
During the Anfinsen experiment, what reagent was used to denature ribonuclease?
urea