At which of the following pH values will the peptide (Ser-Glu-Thr-Ser-Ala-Asp-Gln) bind most tightly to a diethylaminoethyl (DEAE) column? (Matrix--CH2--CH2--NH(CH2CH3)2+)
[A] pH = 8.0
[B] pH = 1.5
[C] pH = 3.95
[D] All of the above would work because pep
[A] pH = 8.0
Which of the following statements about SDS-polyacrylamide gel electrophoresis is incorrect?
[A] Although some rod shaped proteins are rigid, SDS will unfold them and cause them to run purely as a function of the protein's size (molecular weight).
[B] SDS
[B] SDS molecules function to both unfold proteins and coat them with positive charges.
Which of the following statements about ?-sheets and ?-strands is incorrect?
[A] ?-strands in a ?-sheet maintain their structure through cross-strand hydrogen bonds.
[B] The hydrogen bonds that hold ?-strands together in a ?-sheet are made up of atoms fro
[D] The fibrous protein collagen is exceptionally strong due to extensive networks of stacked ?-sheets.
Which of the following statements about protein structure is correct? [A] Raising the temperature of a protein solution will normally result in its unfolding and loss of tertiary structure. Some proteins are able to refold upon reduction of temperature.
[
[A] Raising the temperature of a protein solution will normally result in its unfolding and loss of tertiary structure. Some proteins are able to refold upon reduction of temperature.
Which of the following statements about protein solubility is incorrect?
[A] The solubility of a protein at low ion concentrations usually increases as salt is added.
[B] As more ions are added to the point where they compete with the protein for water mo
[D] Sodium sulfate is the most commonly used reagent for salting out proteins.
Which of the following statements about protein purification is incorrect?
[A] Strings of six histidine amino acids (His6) can be genetically attached to a protein by adding codons for histidine to the gene for the protein at either the N- or C-termini. T
[D] In size-exclusion chromatography only the size of a protein determines the rate at which the protein moves through the column.
For a column that is made from the following material which of the following solutions/conditions would be used to elute the macromolecule off of the column? (Matrix-(CH2)17-CH3)
[A] 2M sodium chloride
[B] imidazole
[C] organic solvent (e.g., acetonitrile
[C] organic solvent (e.g., acetonitrile)
Which of the following statements about ELISA (enzyme-linked immunosorbent assay) is incorrect?
[A] The method usually requires a second enzyme-attached antibody.
[B] The final solution that changes color normally contains the protein of interest.
[C] An
[D] It is a common biotechnological method used to purify antibodies that were raised against a protein of interest.
Which of the following statements about myoglobin and hemoglobin is incorrect?
[A] Myoglobin has a lower p50 than hemoglobin and therefore has a higher affinity for oxygen under most circumstances.
[B] The oxygen binding curve for hemoglobin is sigmoidal
[C] Because the tertiary structures of the four hemoglobin subunits are approximately the same, it binds four O2 molecules with equal affinities.
Certain poisonous gasses such as carbon monoxide bind to the heme of hemoglobin:
[A] with a higher affinity than oxygen.
[B] in a manner that displaces carbon dioxide, causing CO2 poisoning.
[C] from the side opposite oxygen, resulting in a transition fro
[A] with a higher affinity than oxygen.
Which of the following statements about fetal hemoglobin is correct? [A] Fetal hemoglobin has a higher p50 than adult hemoglobin and therefore has a higher affinity for oxygen than adult hemoglobin.
[B] Fetuses that are homozygous for sickle-cell hemoglob
[D] Fetal hemoglobin has a lower affinity for bisphosphoglycerate than adult hemoglobin and therefore has a higher affinity for oxygen than adult hemoglobin.
Which of the following statements about silk-fibroin is correct?
[A] Its secondary structure is maintained by hydrogen bonding between amino-acid sidechains. [B] The flexibility of silk is due, in part, to the relatively weak London dispersive forces that
[B] The flexibility of silk is due, in part, to the relatively weak London dispersive forces that enable stacked ?-sheets to slide past one another.
Which of the following statements about Nuclear Magnetic Resonance (NMR) and X-ray crystallography is correct?
[A] NMR is a form of macromolecular structural elucidation that is far superior to X-ray crystallography.
[B] NMR directly measures the magnetic
[B] NMR directly measures the magnetic properties of atomic nuclei.
Which of the following statements about hemoglobin is incorrect? [A] The Bohr Effect states that C- and N-terminal ion pairs are favored at lower pH and therefore lower pH pushes the T- to R-state equilibrium towards the T-state.
[B] The higher pH found i
[C] Hemoglobin sequentially binds four O2 molecules with increasing affinities and therefore hemoglobin exists in different structural states for each O2 binding.
Which of the following statements about the transition of hemoglobin from the T- to R-state is correct? [A] The energy needed to convert from the T- to the R-state is obtained from the coupled exergonic hydrolysis of ATP.
[B] In the T-state of hemoglobin
[D] Important N- and C-terminal ion pairs form only in the T-state of hemoglobin.
Which of the following statements about myoglobin is incorrect?
[A] The iron atom of myoglobin has six ligands - 4 porphyrin (pyrrole) nitrogen atoms, and two nitrogen atoms (one each) from the proximal and distal histidine side-chains.
[B] Myoglobin prim
[A] The iron atom of myoglobin has six ligands - 4 porphyrin (pyrrole) nitrogen atoms, and two nitrogen atoms (one each) from the proximal and distal histidine side-chains.
Which of the following statements about myoglobin is incorrect?
[A] The heme group is a heterocyclic ring system that is a porphyrin derivative containing four pyrrole groups linked by methene bridges.
[B] The heme group is tightly wedged in a hydrophobic
[C] Myoglobin is monomeric in the deoxygenated state and, in a manner similar to hemoglobin, becomes tetrameric in the oxygenated state.
Which of the following statements about CO2 transport is correct? [A] In humans, when CO2 is converted to bicarbonate in respiring tissue the Bohr protons lower the pH which favors the T-state which has a significantly higher affinity for bicarbonate bind
[D] In the lungs, where the R-state is favored, released Bohr protons recombine with bicarbonate and ultimately drive off CO2.
Which of the following statements about sickle-cell hemoglobin, HbS, is correct?
[A] HbS has the same primary structure as normal hemoglobin but a different tertiary structure. [B] Erythrocytes (red blood cells) that carry OxyHbS or DeoxyHbS have slightly
[C] HbS fibers tend to form in actively respiring tissue where pH and pO2 are lower and the T-state of Hb is favored.
Which of the following statements about hemoglobin is incorrect.
[A] The T and R states of hemoglobin are in equilibrium with one another (T?R). Certain solution conditions will push the equilibrium to one state while different conditions will favor the o
[B] When a T to R transition occurs, ion-pairs at the N- and C- termini begin to form. The pKa values for the groups formally involved in ion-pairs go up and therefore become slightly more basic in the R state.
Which of the following is a normal response to the lower partial pressure of oxygen at increased altitude (i.e., greater than approximately 11,000 feet)?
[A] In a short period of time, lower pO2 levels in the atmosphere favors the T-state within the lungs
[B] In a short period of time, the chemical production of 2, 3-bisphosphoglycerate (BPG) is increased. BPG favors the T-state and interacts with a number of cationic groups located in solvent filled channel of hemoglobin.
The heme group of hemoglobin binds CO2 with higher affinity in respiring tissues where the pH is low in comparison to a much lower CO2 affinity in the lungs. The lower CO2 affinity in the lungs enables the CO2 to "gas-off" upon exhalation.
[A] true
[B] fa
[B] false
The partial pressure of O2 in lungs is approximately 100 torr where the fractional O2 saturation of hemoglobin is about ______. The partial pressure of O2 in venous blood is about 30 torr and the saturation of hemoglobin with O2 is approximately ______.
[
[B] 0.95, 0.55
Which of the following is the correct p50 value for a mutant hemoglobin variant that has a YO2 = 0.86 when the pO2 = 32 torr? The Hill constant for this hemoglobin is 3. YO2 = (pO2) n / [(p50) n + (pO2) n ]
[AB] 22
[AC] 26
[AD] 20
[AE] 24
[BC] 23
[BD] 25
[BE] 21
Match the following autoimmune diseases with the associated target tissue. All must be correct! 1) Systemic lupus erythematosus w) Myelin sheath of nerve fibers 2) Insulin-dependent diabetes mellitus x) Connective tissue 3) Multiple Sclerosis y) DNA, phos
[A] 1 - y, 2 - z, 3 - w, 4 - x
Which of the following statements about antibodies is incorrect?
[A] The great diversity (i.e., combinatorial complexity) associated with IgG antibodies is derived from six hypervariable loops located on the ends of the light chains.
[B] Even though mice
[A] The great diversity (i.e., combinatorial complexity) associated with IgG antibodies is derived from six hypervariable loops located on the ends of the light chains.
Which of the following statements about antibodies is correct?
[A] A novel (newly introduced) antigen stimulates the proliferation of pre-existing B cells whose antibodies just so happen to recognize (and bind to) the antigen.
[B] The monovalent nature of
[A] A novel (newly introduced) antigen stimulates the proliferation of pre-existing B cells whose antibodies just so happen to recognize (and bind to) the antigen.
Which of the following statements about antibodies is incorrect?
[A] Upon infection of a mammal by a foreign organism a small number of pre-existing B-cells are stimulated to divide and proliferate. Vaccination exploits the fact that some of these B-cells
[D] The secondary structure of IgG antibodies consists primarily of ?-helices that form stacked helical bundles that make up the prototypical immunoglobulin fold.
Which of the following statements about amylose and amylopectin is incorrect?
[A] Amylose consists of thousands of glucose monomers linked together by ?(1?4) linkages and each of the monomers contains one reducing group.
[B] Amylopectin and glycogen are s
[A] Amylose consists of thousands of glucose monomers linked together by ?(1?4) linkages and each of the monomers contains one reducing group.
Which of the following statements about Hyaluronic acid and Heparin is incorrect?
[A] Hyaluronic acid is an important glycosaminoglycan component of connective tissue, synovial fluid and the vitreous humor of the eye. [B] Heparin, a major constituent of c
[B] Heparin, a major constituent of connective tissue, promotes blood clotting and thus assists in post-operative healing and scar reduction.
Which of the following statements about chitin is correct?
[A] It is made up of hydrophilic carbohydrate building blocks (i.e., ?-linked monosaccharides) and therefore easily dissolves in water. [B] It is the principal structural component of silk-worm co
[C] It is a homopolymer made up of ?(1?4)-linked N-acetyl-D-glucosamine residues.
Which of the following statements about carbohydrates is incorrect? [A] When a monosaccharide cyclizes, the carbonyl carbon, referred to as the anomeric carbon, becomes a chiral center with two possible configurations, ? or ?.
[B] Glyceraldehyde has one c
[D] Since ? and ? anomers are derived from the same parent carbohydrate, they have very similar physical and chemical properties and form highly similar polysaccharide structures.
Which of the following fractionation procedure would be best for the purification of protein 1 from a mixture of three proteins whose amino acids compositions are as follows? 1. 25% Ala, 5% Gly, 20% Ser, 10% Glu, 10% Val, 5% Asn, 20% Asp, 5% Pro 2. 30% Gl
[A] anion exchange chromatography
. Which of the following statements about cellulose is incorrect?
[A] The super-secondary structure of cellulose was selected for in evolution to render it highly accessible to the enzymes found in bovine (cow) stomachs.
[B] Although the carbohydrate buil
[A] The super-secondary structure of cellulose was selected for in evolution to render it highly accessible to the enzymes found in bovine (cow) stomachs.
Which of the following statements about carbohydrates is incorrect? [A] Carbohydrates are the most abundant biological molecules.
[B] Carbohydrates are combined according to the formula (C � H2O)n, where n ? 3.
[C] Carbohydrates are generally less complex
[D] Ketose carbohydrates generally have one more chiral center in comparison to aldoses that have the same number of carbon atoms.
Which of the following statements about the peptidoglycan component of the bacterial cell wall is correct?
[A] In bacteria, each of the four amino acids of the tetrapeptide form isopeptide links through side-chain groups.
[B] The four amino acids that mak
[C] The repeating disaccharide unit consists of N-acetylglucosamine and N-acetylmuramic acid linked by a ?(1?4) glycosidic bond.
Which of the following is the correct subunit composition of a protein based on the following experimentally derived information? Molecular mass by analytical ultracentrifugation: 900 kD Molecular mass by SDS-PAGE: 300 kD Molecular mass by SDS-PAGE with ?
[B] The entire protein consists of a trimer of homodimers; the homodimers consist of two subunits that are each 150 kD and held together by disulfide bonds.
Identify the name of the molecule, the names of the monosaccharides, and their linkages in the image of the disaccharide below?
[AB] lactose; ?-galactose (14) ?-glucose [
AC] lactose; ?-glucose (12) ?-fructose
[AD] lactose; ?-galactose (16) ?-glucose
[AE]
[BC] sucrose; ?-glucose (12) ?-fructose
Which of the following statements about glycoslyation is correct?
[A] O-linked glycoslyation starts before the protein has completely traversed the endoplasmic reticulum and therefore before it is fully folded.
[B] The site of attachment for O-linked glyc
[C] The recognition sequence for O-linked glycoslyation is a structural feature on the surface of the protein that is recognized by the enzyme that catalyzes glycoslyation.