BCH 261 Study Guide - Midterm Guide: Rossmann Fold, N-Terminus, C-Terminus

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6 Mar 2017
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BCH 261 Mock Exam:
Part A: Multiple Choice (33 questions, 66 total marks)
Answer EACH of the following questions by filling in the corresponding answer on the bubble sheet.
There is only ONE correct answer per question. Each question is worth 2 marks. Any answers indicated
on this question sheet will not be graded; only the bubble sheet will be graded for this section. You will
not be given additional time to copy your answers from this sheet to the bubble sheet.
1. Which of the following statements about water is TRUE?
(A) Pure liquid water has an average of 4.0 hydrogen bonds between molecules. (B) Water is a polar
molecule due to the partial positive charge on the oxygen atom and the partial negative charge on the
hydrogen atom. (C) Adding salt to water increases the number of hydrogen bonds between water
molecules. (D) One water molecule cannot form a hydrogen bond with a second water molecule if that
second water molecule is also part of a hydrogen bond with a third molecule. (E) None of the above.
. I a polpeptide, the Ψ od
A is etee the N ad Cα alpha C atos. B is etee the Cα alpha C ad C arol C atos.
(C) is between the N and C (carbonyl C) atoms. (D) is always rigid with limited rotation. (E) has partial
double bond characteristics.
3. Lysine has 3 ionizable groups, with the following pKa values: 2.1, 9.2 and 10.6. What is the isoelectric
point of this amino acid?
(A) 4.4 (B) 9.9 (C) 12.1 (D) 3.2 (E) 7.0
4. The reference compound for naming D and L isomers of amino acids is
(A) 3-phosphoglycerate (B) glyceraldehyde. (C) 2,3-isphosphoglerate D β-hydroxybutyrate (E)
amantinin
. Whih of the folloig does NOT otai at least oe β-strad? A a Rossa fold otif B a β-
propeller motif (C) a zinc finger motif (D) fibroin (E) none of the above
6. The three-dimensional conformation of a protein may be strongly influenced by amino acid residues
that are very far apart in sequence. This relationship is in contrast to secondary structure, where the
amino acid residues are:
(A) usually near the polypeptide hai’s aio terius or arol terius. B alas side  side i
primary sequence. (C) invariably restricted to about 7 of the 20 standard amino acids. (D) generally near
each other in the primary sequence. (E) often on different polypeptide strands.
. Whih of the folloig peptides ould e ost faoured to adopt a α-helix secondary structure?
(A) LASPLIAVIPLELSLPKAL (B) AKALKLISRRLTIRKYHRT (C) GGGGALGGAGGTHGGGEGG (D)
LADLADSGEALDELASEDAL (E) IALSLIAKLVLASCSLASIAL
8. What is the concentration of OH- in an aqueous solution of 125 mM HCl? (A) 1.2 x 10 -12 M (B) 3.7 x
10 -13 M (C) 3.2 x 10 -11 M (D) 8.0 x 10 -14 M (E) 6.4 x 10 -11 M
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9. In a conjugated protein, a prosthetic group is:
(A) a molecule that binds non-covalently and reversibly to the ligand binding site of a polypeptide. (C) a
permanently associated part of the protein that is not composed of amino acids. (B) a nonidentical
subunit of a protein with many identical subunits. (D) a part of the primary structure of a protein. (E) a
part of the secondary structure of a protein.
11. Which of the following about oxygen binding to hemoglobin is TRUE?
(A) When [O2] is low, hemoglobin is in the R-state and has low binding affinity for O2. (B) When [O2] is
low, hemoglobin is in the T-state and has high binding affinity for O2. (C) When one molecule of O2
binds to one of the binding sites within hemoglobin, this lowers the affinity of other hemoglobin
subunits for O2. (D) When one molecule of O2 binds to one of the binding sites within hemoglobin, this
increases the affinity of other hemoglobin subunits for O2. (E) O2 binding to hemoglobin can best be
described as a form of negative co-operativity.
12. Histidine has three ionizable groups, with pKa values of 2.1, 6.0 and 9.5. A 1.0L solution of 0.5 M
histidine has a pH of 2.1. To this solution, you add 1.0 M of NaOH. What is the pH of this final solution?
(A) 2.1 (B) 4.2 (C) 5.5 (D) 6.0 (E) 9.6
13. You have a solution of pH 5.6 that is a mixture at of the proteins shown below.
(i) 100 kDa, pI = 4.5 (ii) 30 kDa, pI = 8.9 (iii) 100 kDa, pI = 5.0 (iv) 30 kDa, pI = 3.8 (v) 30 kDa, pI = 8.9
(vi) 100 kDa, pI = 6.3
You perform gel filtration chromatography and collect the first fraction that contains some of these
proteins (i.e. it contains the first proteins to elute from this column). You then subject this first fraction
solution to a second round of chromatography, this time a cation exchange column. What is the first
protein(s) to elute from the second column?
(A) (iii) (B) (ii) and (v) (C) (vi) (D) (i) and (iii) (E) (iv)
14. The Anfinsen experiment was the first to demonstrate that
(A) disulphide bonds could form in proteins between the thiol groups of cysteine residues (B) protein
primary structure was sufficient to determine protein secondary and tertiary structure. (C) proteins
otaied α-helicies (D) that the peptide bond had partial double bond character and was therefore
planar. (E) that the groundhog saw his shadow, meaning that spring will arrive mid-June.
15. You weigh out 0.250g of a particular polypeptide and dissolve it in 300 mL of water. This
corresponds to concentration of this polypeptide of 2.61 x 10-4 M. Approximately how many amino acid
residues does this polypeptide have?
(A) 4 (B) 9 (C) 12 (D) 29 (E) this cannot be determined without additional information
16. Which of the following is NOT an example of the movement of water due to osmotic pressure?
(A) the net movement of water into roots at night, generating root pressure (B) the net movement of
water into a cell in a hypotonic environment (C) the net movement of water out of your fingers in a hot
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