Exam 1 Flashcards
(Exam 1) Which of the following is true regarding a reaction that has a ΔG° = 0.
-The concentrations of the reactants and products are equal.
-The reaction will eventually arrive at an equilibrium.
-The reacton will go forward quickly.
-The reacton will go forward slowly.
-The concentration of the product is unchanging.
-The concentration of the product is unchanging.
(Exam 1) The enthalpy of water hydrogen bonding is the driving force behind the hydrophobic effect.
-True
-False
-False
(Exam 1) A protein shows an ability to change its structure between pH 6 and pH 8. A single amino acid is mutated from this protein and the pH sensitivity is no longer present. Which amino acid was
likely replaced by the mutation?
-Threonine
-Proline
-Glycine
-Arginine
-Cysteine
-Histidine
-Histidine
(Exam 1) A polypeptide is found to have a net charge of -3 at pH 7.4. Which of the following sequences is likely the polypeptide?
-DNRPKWLVLWTREED
-DEREVSDYFYSLAGGH
-NEREVSDYFVSLAGAH
-DEREVSDYFYSLAGGH
(Exam 1) Which of the following amino acids is least likely to be found on the outside of a protein?
-Serine
-Threonine
-Glutamate
-Isoleucine
-Tyrosine
-Tryptophan
-Isoleucine
(Exam 1) Due to partial double bond character, the bond between the carbonyl carbon and amide nitrogen does not rotate freely.
-True
-False
-True
(Exam 1) The amide hydrogen of every other peptide bond in an ⍺-helix is hydrogen bonded.
-True
-False
-False
(Exam 1) The structures of a right-handed ⍺-helix and a β-sheet are similar in the following way:
-They both rely on a pattern of n+4 hydrogen bonding along the axis of the structure.
-Their carbonyl oxygens typically only hydrogen-bond with residues that are within five residues in the primary sequence.
-They are both capable of being amphipathic.
-They can both tolerate one proline, but not two prolines as a part of their structure.
-They are both capable of being amphipathic
(Exam 1) The following two amino acid sequences are part of a large protein structure. Which of the following is most likely to be true for each of these sequences?
Sequence 1
FPNPGSIELDRPNPT
Sequence 2
VTFFGAGVISTGSFLT
-Sequence 1 is more likely to form part of the hydrophobic core of the protein.
-Sequence 2 is more likely to form part of an ⍺-helix.
-If they were produced as separate polypep2des, they would have the same net charge.
-If they were produced as separate polypeptides, only Sequence 1 could be detected by monitoring absorbance at 280 nm
-Sequence 2 is more likely to form a part of an ⍺-helix.
(Exam 1) The following amino acid sequence is composed entirely of an α-helix: LISSMIKMLQTLIR
Which of the following is true at pH 7?
-The α-helix is hydrophobic
-The α-helix is hydrophilic
-The α-helix is amphipathic
-The α-helix has a net charge of 0
-The α-helix is amphipathic
(Exam 1) Formation of internal hydrogen bonds is the single largest force that drives protein folding.
-True
-False
-False
(Exam 1) The overall △G for folding a certain protein is – 65 kJ/mol. One amino acid is mutated and the new △G for the protein is now determined to be – 27 kJ/mol. Which of the following most likely represents the mutation that was made?
-A Leucine in the core of the protein was mutated to an isoleucine.
-A threonine at the surface of the protein was mutated into a serine.
-A valine in the core of the protein was mutated into a cysteine.
-A tyrosine near the surface was mutated into a tryptophan
-A valine in the core of the protein was mutated into a cysteine.
(Exam 1)You used a chromatography column to try to purify a protein that is 10 kDa in size. You made sure to avoid using a buffer that matched the predicted isoelectric point of the protein. Some of the elution fractions were run on SDS-PAGE and are shown below, with the lower numbered fractions eluting first. Based only on this information, what can you conclude from this experiment?
-This was a size exclusion column, but ion exchange chromatography is now needed to complete the purification.
-This was a size exclusion column, and the purification is complete.
-This was a nickel affinity column, and the purification is complete.
-This was an ion exchange column, and the purification is complete.
-This was an ion exchange column, but size exclusion chromatography is now needed to complete the purification.
-This was a size exclusion column, and the purification is complete.
(Exam 1) Which of the following pairs of amino acids are capable of forming salt bridges at pH 7?
-Glutamate and leucine
-Glutamate and aspartate
-Aspartate and lysine
-Aspartate and glutamine
-Histidine and arginine
-Aspartate and lysine
(Exam 1) The purpose of hydroxyproline in tropocollagen is to force the left-handed helices to terminate, since hydroxyproline cannot form backbone hydrogen bonding interactions.
-True
-False
-False
