final biochem quiz

At what pH listed below will lysine carry a net charge of (+1) on its most predominant form? a. pH 2.0 b. pH 8.0 c. pH 9.5 d. pH 11.0

8

A helix has hydrogen bonds between the carbonyl group from residue "n" and the amino group of residue "n+3," which of the following is TRUE? a. It has fewer residues per turn than an alpha helix. b. It has more residues per turn than an alpha helix.

A

A low P50 cooresponds to: Select one: a. a high binding affinity b. a low binding affinity. c. a sigmoidial binding curve. d. a hyperbolic binding curve. e. the pressure of oxygen in the lungs at an average altitude.

A

An extremely efficient enzyme called "efficase" catalyzes the conversion of "A" to "B." A researcher decides to mutate the enzyme in order to try to improve it performance. Following active site mutations, a significant reduction in the value of Km and Vmax was observed. Which of the following may have occurred? Select one: a. The affinity of the enzyme for the substrate was increased to a point which did not favor propagation (continuation) of the reaction. b. The decrease in Vmax was not related to the decrease in Km. c. If the reaction was first-order, the change in Km cannot have affected Vmax. d. The stability of E+S (E + A as written above) was increased, thereby increasing the Km. e. The reverse reaction (breakdown of E+A) was favored, slowing the Vmax.

A

Cellular immune response... Select one: a. results in production of more T cells specific to the antigen. b. utilizes B lympocytes to produce antibodies for memory cells. c. inactivates the antigen by marking it for breakdown or degradation with the antigenic determinant. d. does not require additional proteins such as the MHC Class I or II proteins to complete antigen presentation.

A

Consider the graph shown below. Based on this graph would you expect that ATP binding inhibits activity of this enzyme? Hint: Estimate the Km from each curve and consider how a change in Km would affect enzyme activity? Select one: a. Yes ATP inhibits the activity of this enzyme. b. No ATP does not inhibit the activity of this enzyme.

A

If an enzyme-catalyzed reaction has a low rate at low pH and high rate at higher pH, this implies that a group on either the enzyme or the substrate must be ______ for an efficient reaction. Select one: a. Deprotonated b. Protonated c. Neutral d. Rate-limiting

A

If the following protein sequence were in solution at pH 12 and was reacted with trypsin, what fragments would be produced? Lys - Met - Arg - Glu - Phe - Gly - Met - His - Phe - Glu a. Lys-Met-Arg Glu-Phe-Gly-Met-His-Phe-Glu b. Lys Met-Arg Glu-Phe-Gly-Met-His-Phe-Glu c. Lys Met-Arg Glu-Phe-Gly-Met-His Phe-Glu

A

In a lock and key enzyme... Select one: a. The active site is specific for the substrate b. Conformational changes occur upon binding the substrate c. The transition state is lower in energy than the products d. The enzyme substrate complex is distorted by structure of the active site e. Proximity and orientation are not a factor in catalysis

A

In the plot below, estimate Km? a. 0.4 mM b. 7 microM c. 14 microM/min d. 14 microM e. 7 microM/min

A

Is the carboxyl group negative or neutral on the most predominant form of phenylalanine at pH 3? a, negative b. neutral

A

Patient "D" was dehydrated and had electrolyte imbalance. Assume at time of treatment the patient is a 75 kg person with a starting osmolality of 300mOsmoles/kg. The patient was treated with 1 liter of distilled water. Answer the following questions two questions.What is the patient's final Osmolality after treatment with 1 liter of distilled water? Select one: a. 293.5 mOsm/kg water b. 13500 mOsm/kg water c. 900 mOsm/kg water d. 30 mOsm/kg water e. There is no change in the paitent's osmolarity (300 mOsm/kg water).

A

What of the following contributes to the high energy of ATP? Recall the structure of ATP involves negatively charged phosphate groups adjacent to each other. Select one: a. Charge-Charge repulsion b. London Dispersion forces c. Ionic bonds d. Charge-dipole interaction e. Charge-Charge attraction

A

When considering fibrous proteins, which of the following statements is true? Select one: a. Non-covalent interactions contribute to the strength of all of these proteins. b. All of them consist of alpha helix structure. c. All of them require vit C. d. Decrease in amounts of any of them cause Scurvy. e. All of these are true of fibrous proteins.

A

Which of the following best describes the cause or Creutzfeld-Jakob Disease? Select one: a. Aggregation of a misfolded protein. b. Precipitation of a hyperphosphorylated protein. c. Ingestion of ammonium salts. d. The serious side effects of experimental treatment with Quinacrine. e. All are potential causes Creutzfeld-Jakob Disease.

A

Which of the following is NOT true about enzymes? Select one: a. Enzymes catalyze the reaction in only the forward direction. b. Enzymes are often very specific for their substrates. c. Enzyme activities can often be regulated. d. Enzymes typically act under milder conditions of temperature and pH than chemical catalysts. e. Enzymes typically catalyze reactions at much higher rates than chemical catalysts.

A

Which structural protein uses a modified hydroxylated amino acid to increase its stability? Select one: a. collagen b. elastin c. fibroin d. All of the above.

A

The sodium glucose transporter... SELECT ALL THAT APPLY Select one or more: a. uses a concentration gradient developed from the sodium potassium pump to transport glucose. b. has an ATP binding site, where ATP is hydrolyzed. c. is an example of secondary active transport. d. is an example of primary active transport. e. exchanges sodium ions for glucose molecules

A C

Which of the following statements is TRUE regarding hemoglobin? Select all that apply. Select one or more: a. A low P50 on an oxygen binding curve corresponds to high oxygen affinity. This is one correct answer. b. Binding of BPG increases the P50. This is one correct answer c. A decrease in pH increased the P50. This is one correct answer. d. None of the above are true.

ABC

Good enzymes... (Select all that apply.) Select one or more: a. Must bind substrate well. b. Must not bind the substrate too well. c. Must convert substrate to product efficiently d. Must not bind the product too well.

ABCD

What type of catalysis is utilized by chymotrypsin? Select all that apply. Select one or more: a. Acid-base catalysis b. covalent catalysis c. proximity effects d. Strain e. Peptide catalysis

ABCD

Which of the following is TRUE regarding hydrogen bonds in water? (SELECT ALL THAT APPLY) Select one or more: a. They occur because the water molecules are polar. b. They are partially covalent. c. They are partially charge-charge (or dipole-dipole) interactions. d. They are important because there are so many in our body.

ABCD

In the body hydrogen ions produced from the reaction of carbonic anhydrase are transported into the lumen of the stomach via an ATP utilizing proton pump. The removal of hydrogen ions drives formation of bicarbonate ions and concentration gradient. Bicarbonate is transported out at the same time that chloride ions are transferred in. Based on this information, which of the following is TRUE ? SELECT ALL THAT APPLY Select one or more: a. The pump driving the driving the hydrogen ions into the lumen must undergo a conformational change b. The pump driving bicarbonate out and chloride in must be an antiport system. c. The pump driving bicarbonate out and chloride in must require ATP directly. d. The bicarbonate-chloride transfer is an example of passive transport e. The bicarbonate-chloride pump must require activity of the proton pump

ABE

Consider the following reaction where E1 is the enzyme that catalyzes conversion of A to B and E2 is the enzyme the catalyzes the conversion of B to C, etc. Predict what would happen if enzyme E1 had an allosteric site that was specific for compound D. Select one or more: a. E1 would be inhibited by D via allosteric control. b. Compound D would not affect E1 even if it did bind because E1 does not use D as a reactant or product. c. The graph showing the binding of B to E1 would appear sigmoidal when D is also bound to E1. d. The graph showing the binding of B to E1 would appear hyperbolic when D is also bound to E1.

AC

A lab recently developed a new drug which is hypothesized to inhibit the enzyme cyclooxygenase-2 (cox-2) and reduce inflammation. In their first test they monitored the reaction of substrate as it is converted to product in the presence of the new drug. They have collected the following data. Based on this data, estimate the initial velocity. a. 7 mol/L/second b. 1.4 (mol/L)/second c. 21 mol/L d. 0.95 (mol/L)/second e. 1.4 seconds

B

A molecule "X" which normally has no dipole moment comes into close proximity of a strong cation. "X"now develops partial charges in response to the cation. Which of the following is true? Select 1 answer. Select one: a. "X"must be an anion. b. "X" is involved in a charge-induced dipole interaction. c. "X" is involved in a dipole-dipole interaction. d. "X" has a permanent dipole. e. "X" is involved in London dispersion forces

B

A patient in a car accident was admitted to the emergency department with swollen and congested lungs. His physiological pH was found to be 7.2. He was complaining of bad headache, dizziness and disorientation. Use the information on pages 14-20 of the "Physiological_pH_buffers" notes to decide which of the following is a treatment you would recommend for this patient knowing that all solutions listed below are sterile and isotonic to blood? Select one: a. Intravenous injection of sodium hydroxide solution b. Intravenous injection of sodium bicarbonate c. Intravenous solution of acetic acid solution d. Intravenous injection of hydrochloric acid solution

B

Acid-base catalysis usually is accomplished by: Select one: a. active site specificity b. charge delocalization c. nucleophilic catalysis d. Strain e. conformational change

B

At low substrate concentrations, Select one: a. the rate of reaction is expected to be inversely proportional to substrate concentration. b. the rate of reaction is expected to be directly proportional to substrate concentration. c. first order enzyme kinetics are not observed. d. the Km is lower. e. the rate of reaction is independent of substrate concentration

B

At pH 9, will tyrosine carry a NET charge in its most predominant form? a. yes b. No

B

Based on the information on page 11 of the acid_base_buffer notes, which of the following is the salt that results from the reaction below? Ca(OH)2 + HCOOH H2O + Formic acid Select one: a. sodium formate b. calcium formate c. calcium carbonate d. calcium chloride e. ammonium sulfate

B

Based on the information on pages 1 and 2 of the acid_base_buffers document, which of the following is a correct statement? Select one: a. VN2 refers to the concentration of sodium in the blood b. PN2 refers to the concentration of nitrogen in the blood c. VNa refers to the concentration of sodium in the blood d. PNa refers to the concentration of sodium in the blood

B

Consider the following metabolic reaction:Succinyl-CoA (s)+ Acetoacetate(s) -> Acetoacetyl-CoA(high energy) + Succinate (s) ΔG°' = (+)1.25 kJ/molThis reaction is Select one: a. favorable under standard conditions. b. not favorable under standard conditions. c. always exergonic and can never proceed in the opposite direction. d. spontaneous as written when [succinate] and [acetoacetyl-CoA] are high. e. None of the above

B

In a micelle or bilayer, the surrounding water is in contact with the more _____ portion of the amphiphilic molecule. Select one: a. hydrophobic b. hydrophilic c. Non-polar d. Positive e. Negative

B

Relying mainly on the information provided on pages 17 through 20 of the acid-base-buffers notes, choose from the answer choices below the group of words that best completes the following sentence: Some drugs, e.g. the salicylates, stimulate the respiratory center in the brain causing patients on high doses to hyperventilate as a side effect. Such patients may have blood pH values _____________ the normal value of 7.4. Other groups of drugs, e.g. the barbiturates, suppress the respiratory center causing patients on high doses to hypoventilate. Those patients may have blood pH values _____________ the normal value of 7.4. Select one: a. slightly less than slightly more than b. slightly more than slightly less than c. slightly less than equal to d. equal to equal to e. equal to slightly more than

B

The binding curve for hemoglobin is ______ and the binding curve for myoglobin is ________. Select one: a. Sigmoidial; sigmoidial b. Sigmoidial; hyperbolic c. Hyperbolic; sigmoidial d. Hyperbolic; hyperbolic e. Super curvy; super curvy

B

The structure at right is for bacteriorhodopsin. Which arrow points to a location with a Beta hairpin? Select one: a. A b. B c. C

B

What is the 2nd most predominant form of arginine at pH 9.7? Note: Find the second most predominant form not the most predominant form. a. Net charge (+2) b. Net charge (+1) c. Net charge 0 d. Net charge (-1)

B

What is the second most predominant form of methionine at pH 4? a. alpha-amino (+); alpha-carboxyl (-) b. alpha-amino (+); alpha-carboxyl (neutral) c. alpha-amino (neutral); alpha-carboxyl (-) d. alpha-amino (neutral); alpha-carboxyl (neutral) e. alpha-amino (-); alpha-carboxyl (neutral)

B

Which of the following best described the Bohr effect? Select one: a. A increase in pH lowers the affinity of hemoglobin for oxygen. b. An increase in CO2 lowers the pH and shifts the sigmoidial binding curve from higher affinity to lower affinity of hemoglobin for oxygen. c. Hemoglobin's affinity for O2 will increase as tissues release CO2. d. The Bohr effect occurs as a result of Histidine 97. e. The Bohr effect only affects binding affinity if the hemoglobin is half full.

B

Which of the following is TRUE regarding entropy? Select one or more: a. It is higher in a liquid than in a gas. b. It is higher in ADP + Pi than in ATP c. It is higher at lower temperatures. d. It is higher if a reaction has a negative Delta H e. It is independent of temperature.

B

Which of the following would be most stable based on the information you have learned about protein structure? a. a β hairpin with 12 amino acids b. a β sheet region made up of amino acids Val, Ile, Phe c. an α helix made up of Cys, Pro, and Phe d. a loop region with 8 amino acids e. All have equal stability.

B

What is the pI of lysine? a. 10.54 b. 9.74 c. 9.06 d. 5.61 e. 2.16

B Correct. pI = (pka2 + pKa3)/2 = (8.95+10.53)/2 = 9.74

A new enzyme target for antibiotic design catalyzes a reaction which converts a L-amino acid into a D-amino acid. What class of enzyme is this new target? Select one: a. Transferase b. Oxidoreductase c. Isomerase d. Hydrolase e. Lyase

C

A patient who has been receiving high dose vancomycin treatment for two weeks due to a resistant bacterial infection has developed a mild case of cardiac arrhythmia (irregular heartbeats). Knowing that high doses of vancomycin severely impair kidney function, and based on the information on page 19 and 20 of the acid-base-buffer notes, which of the following is most likely true about this patient? Select one: a. The patient's blood pH is less than 7.4 b. The patient's blood pH is equal to 7.4 c. The patient's blood pH is more than 7.4

C

At pH 4, will the side chain on the most predominant form of aspartate (aspartic acid) be charged and if so will it be (+) or (-)?

C

Based on the information presented on pages 10 and 11 of the acid_base_buffer document, which of the following is the best example of a neutral buffer? Select one: a. a solution of acetic acid in pure deionized distilled water that has an overall [H+] = 10-7 b. pure, deionized distilled water at pH 7 c. a solution containing H2PO4¯ and HPO42- with an overall [H+] = 10-7 d. a mixture of sodium acetate and citric acid that has a pOH of 8

C

Based on what you know about fibrous protein structure and sequence, what type of fibrous protein is this sequence most likely from (You can assume that the protein is longer than what is shown)? Lys - Hyp - Gly - Ala - Hyp - Gly - Ala - Val - Gly - Hyp - Lys - Gly - Pro - Val - Gly - Hyp - Ala Note: Hyp = hydroxyproline Select one: a. alpha Keratin b. Fibroin c. Collagen d. Elastin

C

How many ATPs could be formed from ADP and Pi if the reaction were coupled to glucose + 6 O2 <-> 6 CO2 + 6H2O, delta G = (-)2872 kJ/mol? Assume (Delta)Go = -1713 kJ/mol for the coupled reactions. Select one: a. 26 ATPs b. 34 ATPs c. 38 ATPs d. 51 ATPs e. 16 ATPs

C

If doing a protein extraction, where might you find Elastin? Select one: a. hair b. spider webs c. blood vessels d. tendons e. skin

C

Km: Select one: a. is the concentration of substrate where the enzyme achieves Vmax. b. is equal to Kd. c. measures the stability the E-S. d. is high if the enzyme has high affinity for the substrate. e. All of the above are correct.

C

Person "A" drinks 5 liters of distilled water. Which of the following is TRUE? Select 1 answer. Select one: a. The final ECF volume has decreased b. The final ICF volume has decreased c. The final osmolaity has decreased. d. The final osmolaity has increased. e. The total body osmoles have decreased.

C

The structure of deoxyhemoglobin is stabilized by each of the following EXCEPT: Select one: a. BPG binding. b. salt bridges between chains c. coordination of the heme cofactor with the distal histidine d. Lower pH in the tissues as a result increases CO2 e. hydrogen bonding between chains

C

Use the information in the table to answer the next few questions. Assuming that the enthalpy change for aerobic oxidation of glucose is (-) 2816 kJ/mol, determine the entropy change at 37 degrees C. Note delta G for this reaction is (-)2872 kJ/mol. ReactionFree energy A C6H12O6 + 6O2 <--> 6CO2 + 6H2O aerobic oxidation of glucose(-) 2872 kJ/molB C6H12O6 <--> 2(CH3CH2OH) + 2CO2 fermentation of glucose(-) 2818 kJ/molC C6H12O6 <--> 2(CH3CHOCHOO-) + 2H+ anaerobic oxidation of glucose(-) 116 kJ/mol Select one: a. 2872 kJ/mol b. 0.2872 kJ/mol c. 0.181 kJ/mol d. 2816 kJ/mol e. 181 kJ/mol

C

Using the calculations on page 18 of the acid-base-buffers notes as a guide, what is the pH of a 0.2 M buffer X (pKa = 4.77) that contains twice as much acid as conjugate base? Select one: a. 5.07 b. 3.77 c. 4.47 d. 4.77

C

What is the most predominant form of lysine at pH 9.5? a. Net charge (+2) b. Net charge (+1) c. Net charge 0 d. Net Charge (-1)

C

An acetate buffer was prepared at pH 4.88 using a mixture of acetic acid (pKa = 4.76) and sodium acetate. Using the equations on page 14 and those on page 18 of the acid-base-buffers notes and some of your creative thinking skills, what is the percentage of the ionized form of acetic acid in this buffer? Select one: a. Approximately 2×10-8 % b. Approximately 98% c. Approximately 50% d. Approximately 57% e. Approximately 100%

D

Based on the information provided on pages 6 through 8 of the acid-base-buffer notes, which of the following is the best example of strong acids? Select one: a. a Bronsted acid with an infinitely small Ka b. an acid with a pKa of more than 7 c. an Arrhenius acid that produces 10-8 moles or less of H+ in 10 liter solution d. a Lewis acid with an infinitely large Ka

D

Competitive inhibitors... Select one: a. Bind in a location other than the active site. b. Interact with a different form of the enzymes than the substrate c. Effects the value of Vmax d. Effects the value of Km

D

Enzymes which have an extremely specific active site... Select one: a. May have a higher Km for the substrate than enzymes with non-specific active sites. b. May not bind the substrate efficiently. c. May not form the E-S complex readily. d. May have a smaller Km for the substrate than enzymes with non-specific active sites.

D

Given the following information, why are diamonds not forever?C(diamond) -> C(graphite) ΔGo=(-)2.88 kJ/mol Select one: a. Because at high temperature, the reaction is not favored. b. Because the enthalpy change must be positive. c. Because no work is done. d. Because the free energy change is negative.

D

Hemoglobin performs a different function than myoglobin because: Select one: a. It has more than one subunit. b. It demonstrates cooperative binding. c. It transfers oxygen from high pressure areas to low pressure areas. d. All of these enable hemoglobin to perform a different function e. None of these enable hemoglobin to function differently.

D

In the humoral immune response which of the following cell types secrete anitbodies or immunoglobulins? Select one: a. Helper T cells b. Immunoglobin cells c. Interleukin 2 cells d. B lymphocytes or B cells

D

In the process of extracting the protein from the cells, the biochemist uses ammonium sulfate. Which of the following is TRUE? I. The protein stability has increased. II. The protein is less likely to denature. III. The protein was salted out. a. III only b. I and II c. I and III d. I, II, III e. II only

D

In which pH range given below will the most predominant form of arginine be zwitterionic? a. pH 0-2 b. pH 2.5-8.5 c. pH 6-9.5 d. pH 9.1-11 e. pH 9.1-14

D

Proteins can denature due to a change in: Select one: a. pH b. temperature c. ionic strength d. All of the above. e. e. None of the above

D

The peptide shown below is an antibiotic. Which of the following list the amino acids that make up this peptide? a. -Arg-Val-Tyr- b. -Asn-Leu-Tyr - c. -Asn-Ile-Phe- d. -Arg-Ile-Phe-

D

The transition state of an enzyme and substrate reaction: Select one: a. Must always bind the enzyme active site with lower energy than the products. b. Is stabilized by enhancing the reverse reaction of E+S->E-S. c. Is composed of true covalent bonds which decreases its energy. d. Is stabilized by the specificity of the active site for the substrate. e. Is stabilized by decreasing the effective concentration.

D

What is the most predominant form of leucine at pH 1.8? a. alpha-amino (+); alpha-carboxyl (-) b. alpha-amino (-); alpha-carboxyl (-) c. alpha-amino (neutral); alpha-carboxyl (-) d. alpha-amino (+); alpha-carboxyl (neutral) e. alpha-amino (neutral); alpha-carboxyl (neutral)

D

Which one of these characteristics is TRUE for the beta sheet? a. Glycine is not commonly found in beta sheets b. Hydrogen bonds form between residues n and n+4 c. Glycine is every third amino acid residue. d. Beta strands are parallel if the N-terminus of each strand align

D

Digitoxin ultimately results in increased sodium ions and calcium ions in the cell which effectively increase the force with each heart beat. Which of the following is the role for calcium in this process? Select one: a. Calcium binds to the G-actin b. Calcium binds in place of the myosin head group. c. Calcium aids in formation of the F-actin filament. d. Calcium increases the width of the A band and decrease the width of the I band e. Calcium binds troponin which are bound to tropomyosin.

E

Patient "D" was dehydrated and had electrolyte imbalance. Assume at time of treatment the patient is a 75 kg person with a starting osmolality of 300mOsmoles/kg. The patient was treated with 1 liter of distilled water. Answer the following question.What is the patient's change in total body osmoles following the addition of 1 liter of distilled water? Select one: a. The patient went from 4500 mOsm to 13500 mOsm b. The patient went from 13500 mOsm to 4500 mOsm c. The patient went from 9000 mOsm to 4500 mOsm d. The patient went from 13500 mOsm to 9000 mOsm e. There is no change in the number of Osmoles.

E

Proximity effects: Select one: a. are caused by active site specificity b. are caused by substrate channeling c. result in increased effective concentration d. lower the energy of activation e. all of the above

E

Which of the following describes the adenylate cyclase signaling cascade most correctly? Select one: a. Glucagon binds its receptor protein, which stimulates the production of ATP. b. Glucagon binds its receptor protein, which stimulates the three subunits of the G-protein to bind ATP c. Binding of epinephrine to the receptor signal the conversion of GTP to cAMP. d. Binding of Glucagon to its receptor signals the G protein begin producing cAMP. e. Binding of the GTP bound alpha subunit to adenylate cyclase signals production of cAMP.

E

Which of the following is TRUE? I. The structure is predominantly parallel beta sheet II. The structure contains a beta-alpha-beta region III. The structure contains multiple beta hairpins a. II only b. III only c. I, II, III d. I only e. II and III

E

Which of the following might the sequence below form? Ile - Phe - Trp - Val - Phe - Val - Val - Arg - Pro - Pro -Asp - Ala - Leu - Met - Glu - His - Lys a. beta - alpha - beta b. beta sheet c. helix - loop - helix d. alpha helix e. beta- turn - alpha

E

Based on the information on page 10 of the acid_base_buffer notes, is the following statement TRUE or FALSE: A solution that has a pH of 8 has more protons in it than a solution that has a pH of 3 Select one: True False

False

From figure "1" in the "Physiological_pH_buffers" notes, we can determine that approximately 40% of the oxygen binding sites on hemoglobin are saturated with oxygen at the physiological pH and at an oxygen concentration of 22 mm Hg. True False

True

Which of the following properties of water are responsible for maintaining body temperature? a. High viscosity, High heat of Vaporization b. High Heat of Vaporization, High Heat Capacity c. High Heat Capacity, Low molecular weight d. High dielectric constant, High Heat Capacity

c