Exam 1 Practice Exams

Question 1

Which of the following is true?

a. DNA is used as the template during transcription.
b. RNA is used as a template during the transcription of protein.
c. dGTP and GTP differ at the 3’ position, as dGTP is reduced at this position while GTP is not.
d. All the above are true
e. Only b and c are true

Answer 1

a. DNA is used as the template during transcription.

Question 2

Which of the following, regarding lipids, is false?

a. Lipids are largely polar in nature.
b. Cell membranes are largely made up of lipids and protein.
c. Lipids can provide structure.
d. Lipids can act as signaling molecules.

Answer 2

a. Lipids are largely polar in nature.

Question 3

Which of the following is false?
a. Proteins are polymers of amino acids joined together by peptide bonds.
b. In the lipid bilayer, lipids are held together by covalent bonds to form the lipid membrane.
c. In aqueous solution, proteins form hydrogen bonds with water molecules.
d . In aqueous solution, polar amino acids are most commonly on the outside of a protein, while non-polar amino acids are generally buried inside the protein, away from the aqueous solution.

Answer 3

b. In the lipid bilayer, lipids are held together by covalent bonds to form the lipid membrane.

Question 4

Which of the following are true regarding covalent bonds:

a. Bonding valence electrons are attracted by both nuclei in the bond.
b. Bond length depends on the nature of the atoms bonded and the number of electrons participating in the bond.
c. Carbon-carbon double bonds are generally longer and have less bond energy than do carbon-carbon triple bonds.
d. All the above are true
e. Only a. and b. are true

Answer 4

d. All the above are true

Question 5

Select the true statement in describing the genetic code:

a. Each of the 64 codons encodes one amino acid.
b. One codon can correspond to more than one amino acid.
c. One amino acid can be encoded by two or more codons.
d. All of the above are true.
e. Only b and c are true.

Answer 5

c. One amino acid can be encoded by two or more codons.

Question 6

Please select the true statement:

a. In metabolically active tissues, CO2 is used to produce oxygen in a reaction catalyzed by carbonic anhydrase.
b. The concentration of carbon dioxide is lower in metabolically active tissues than in the lungs.
c. The heme ring is entirely non-polar in nature.
d. Hemoglobin in the tense state has a lower affinity for oxygen than hemoglobin in the relaxed state.

Answer 6

d. Hemoglobin in the tense state has a lower affinity for oxygen than hemoglobin in the relaxed state.

Question 7

Proline does not have chiral stereochemistry at the alpha carbon, because it is an imino acid.

a. True
b. False

Answer 7

b. False

Question 8

Please select the true statement, for a solution in water under standard conditions:

a. The pH of a 0.1 M solution of the strong base, KOH is 1
b. The pH of a 0.01 nM solution of the strong base, KOH is 11
c. The pH of a 0.1 M slution of acetic acid, a weak acid, is 1
d. None of the answers, a-c is correct.

Answer 8

d. None of the answers, a-c is correct.

Question 9

Please select the true statement:

a. The globin polypeptide is primarily beta sheet.
b. Hemoglobin functions as a tetramer and shows allosteric binding kinetics.
c. The prosthetic group of deoxyhemoglobin includes an iron ion which is in the 3+ oxidation state
d. The function of myoglobin is to store oxygen in the muscles.
e. All of the above are true.
f. Only b, c, and d are true.
g. Only b and d are true.

Answer 9

g. Only b and d are true.

Question 10

Please select the true statement:

a. Adult hemoglobin becomes the predominant form of hemoglobin shortly before birth.
b. Super-oxide is ⋅O2-
c. Fetal hemoglobin is α2β2 tetramer.
d. At high pCO2, hemoglobin has a greater affinity for oxygen than when at low pCO2.

Answer 10

b. Super-oxide is ⋅O2-

Question 11

Please solve for pH if the pKa of the acid is 9 and the concentrations of acetic acid is 1 mM and the concentration of Acetate is 100 mM.

a. pH= 9.2
b. pH= 11
c. pH= 7
d. pH = 7.2
e. The correct answer is not given

Answer 11

b. pH= 11

Question 12

Please identify the true statement regarding water:

a. The bulk of water is ionized in solution. (Water molecules are predominantly found in the ionized state.)
b. The conjugate base of water is H30+
c. Water is permanent dipole with partial charges at the oxygen and each of the hydrogen atoms
d. Water is non-polar

Answer 12

c. Water is permanent dipole with partial charges at the oxygen and each of the hydrogen atoms

Question 13

Choose the false statement:

a. Peptide bonds covalently link the alpha-carboxyl group of one amino acid to the alpha-amino group of another amino acid.
b. The four major groups of macromolecules are nucleic acid, protein, lipids and carbohydrates
c. Acids are proton donors, bases are proton acceptors
d. The entropy of the universe is constant.

Answer 13

d. The entropy of the universe is constant.

Question 14

Based on the pKa values of side chains at pH 7, which of these tri-peptides contains, from N’- to C’-terminus, neutral – basic – acidic residues?

a. Ile-Arg-Lys
b. Val-Lys-Asn
c. Asp-Arg-Val
d. Gly-Lys-Glu
e. Met-Arg-Gly

Answer 14

d. Gly-Lys-Glu

Question 15

Please select the false answer:

a. A covalent bond between two carbon atoms has a higher bond energy than the van der Waals interactions between two hydrogen atoms.
b. Ionic bonds are non-directional.
c. Hydrogen bonds are stronger when all of the atoms involved in the bond are in a linear orientation with respect to one another.
d. Hydrogen bonds among small molecule solutes in hexane, are weaker than hydrogen bonds between these same solutes in water.

Answer 15

d. Hydrogen bonds among small molecule solutes in hexane, are weaker than hydrogen bonds between these same solutes in water.

Question 16

Please select the true statement:

a. The four elements at the highest mole percent in humans are H, C, N, O
b. Amino acids in living organisms are in the D-configuration
c. When proteins are comprised of single peptide chains, they are said to have secondary structure, but they do not have tertiary structure; the term tertiary structure is reserved for multimeric proteins only.
d. The term motif refers to the interactions between domains to form a functional tertiary structure.

Answer 16

a. The four elements at the highest mole percent in humans are H, C, N, O

Question 17

Select the true answer regarding peptides.

a. To stabilize quaternary structures, individual polypeptide subunits covalently bond their free amino and carboxyl ends
b. Peptide bonds show partial double bond characteristics
c. Interactions between amino acid side chains determine whether any two given amino acids residues will form a peptide bond
d. There are no correct answers here.

Answer 17

b. Peptide bonds show partial double bond characteristics

Question 18

The amino acid sequence of a yeast protein is 60% identical to its human homolog. The DNA sequences of the genes that encode these two proteins, however, are only 45% identical. How can this be?

a. Mutations leading to differences in DNA sequence might not lead to differences in amino acid sequence, because the genetic code is overlapping.
b. The genetic code is degenerate.
c. DNA is often mutated by radiation, while proteins are more stable.
d. There are more stringent selection pressures on maintaining the correct amino acid sequence than DNA sequence, as changes in amino acid sequence often result in loss of function, while changes in DNA sequence might not result in a change in protein function.
e. All the above are true.
f. Only b and d are true.
g. All but c are true.

Answer 18

f. Only b and d are true.

Question 19

Choose the false statement regarding alpha helices

a. Alpha helices are held in position by hydrogen bonds between main chain atoms.
b. Alpha helices are ordered with amino acid R-groups projecting outward from the helix.
c. Prolines are amino acids commonly found throughout the length of alpha helices.
d. Stabilizing hydrogen bonds are parallel to the axis of the helix and are formed between amino acids that are 3 to 4 residues apart.

Answer 19

c. Prolines are amino acids commonly found throughout the length of alpha helices.

Question 20

select the false statement regarding weak forces

a. Hydrogen bond formation is important for maintaining DNA structure.
b. Ionic interactions are attractive or repulsive forces between charged atoms.
c. The dielectric strength of the solution has little effect on strength of ionic interactions.
d. Strength of ionic interactions depends in part on the proximity of the ions.
e. Ionic interactions are stronger between charged molecules in non-polar solvents.

Answer 20

c. The dielectric strength of the solution has little effect on strength of ionic interactions.

Question 21

Translate this partial sequence:  
5’ ATGAGTGAGATT 3’
3’ TACTCACTCTAA 5’
a. Met, Ser, Glu, Leu                 
b. AUGAGTGAGAUU 
c. Met, Ser, Glu, Ile
d. UACUCACUCUAA
e. Tyr,Ser,Leu,Stop

Answer 21

c. Met, Ser, Glu, Ile

Question 22

tRNA is an adapter RNA that covalently binds to amino acids and hydrogen bonds with codons in the RNA template

a. True
b. False

Answer 22

a. True

Question 23

Select the false statement regarding weak forces:

a. Buffers are weak acids that buffer most effectively at the pKa of the acid, but can buffer within one pH unit above and below the acid’s pKa.
b. At the pKa of an acid, the acid and its conjugate base are at equimolar concentrations.
c. The phosphate buffer system is the primary blood buffer in our bodies.
d. Free amino acids can function as buffers.

Answer 23

c. The phosphate buffer system is the primary blood buffer in our bodies.

Question 24

If the molar concentration of a product increases relative to molar concentration of the starting reactants, this will have what effect on the free energy of the reaction?

a. No effect whatsoever.
b. It will cause ∆G to increase.
c. It will cause ∆G to decrease.
d. It will cause the reaction to become more favorable.
e. Only b and d are true.
f. Only c and d are true.

Answer 24

b. It will cause ∆G to increase.

Question 25

Chimp myoglobin and human myoglobin represent protein paralogs. a. True b. False

Answer 25

b. False

Question 26

The distal histidine in hemoglobin is a coordination point for the heme central iron. a. True b. False

Answer 26

b. False

Question 27

Nucleotides are held together in the nucleic acid polymer by covalent phosphodiester bonds. a. True b. False.

Answer 27

a. True

Question 28

Catabolic pathways are largely divergent, oxidizing and exergonic overall. a. True b. False

Answer 28

a. True

Question 29

∆H=9 kJ/mol, T=278˚K and ∆S = 1OO J/mol˚K What is ∆G? Will this reaction go in the forward direction, spontaneously?

Answer 29

``` ∆G = ∆T - ∆H* ∆S = 9 kJ/mol - 278˚K * 1OO J/mol˚K = 9 kJ/mol - 278˚K * 0.1k J/mol˚K = 9kJ/mole – 27.8 kJ/mol = -18.8 kJ/mol or -18800 kJ/mol Will go in the forward direction spontaneously because ∆G is negative. ```

Question 30

Show the reaction catalyzed by carbonic anhydrase; make sure to include ALL reactants and products.

Answer 30

H2O + CO2 arrows H2CO3. | This is a reversible reaction.

Question 31

Why is the distal histidine important for proper red blood cell function?

Answer 31

The distal histidine acts as a steric impediment to large groups entering the iron binding pocket. Large groups like CO and CO2 are less likely to bind iron. (decreases the affinity of heme for CO for instance) This histidine also stabilizes the bound dimolecular oxygen so that it leaves as O2, not O2-.

Question 32

What is the ratio that describes the relative concentration of the acidic form of the amino acid aspartic acid, in a solution of aspartic acid/aspartate when the pH of the solution is 2.8? Please note that the pKa of this R-group is assumed to be 4.

Answer 32

first set up the Henderson Hasselbalch equation: 2.8=4+log [A-]/[HA]. -1.2 = log [A-]/[HA] so therefore 1.2 = log[HA]/[A-], antilog 1.2 = [HA]/[A-], 10^ 1.2 = [HA]/[A-]

Question 33

At what pH would the ratio of aspartic acid/aspartate be 10/1?

Answer 33

pH is in log scale. If pH is below the pKa the acid dominates. Since the concentration [HA]/[A-] is 10/1 the pH must be below the pKa by one pH unit. To check: 3 = 4+log [A-]/[HA] therefore 3-4 = log [A-]/[HA]-1 = log [A-]/[HA] or flip and 1 = log [HA]/[A-]. Take the antilog of both. 10^1/1 = HA]/[A-].

Question 34

Which of the following is NOT one of the 4 classes of macromolecules: a. proteins b. nucleic acids c. vitamins d. lipids

Answer 34

c. vitamins

Question 35

The enzyme used in your experiment has an optimal of pH of 6.3. You must choose a buffer to use during your experiment. Which of the buffers below will you use? a. Buffer A: pKa = 7.8 b. Buffer B: pKa = 4.8 c. Buffer C: pKa1 = 4.8, pKa2 = 8.8 d. Buffer D: pKa1 = 3.8, pKa2 = 7.8 e. Buffer E: pKa1 = 2.8, pKa2 =5.8

Answer 35

e. Buffer E: pKa1 = 2.8, pKa2 =5.8

Question 36

Please select the false statement: a. The four most prevalent elements in biosystems, in random order, are. H,O,N,C. b. The chiral amino acids found in biosystems are D-stereoisomers. c. Hydrogen bonds are weaker than covalent bonds. d. The strength of ionic bonds is inversely proportional to the dielectric constant of the solvent.

Answer 36

b. The chiral amino acids found in biosystems are D-stereoisomers.

Question 37

Please select the true statement: a. A peptide bond is a covalent bond formed between the alpha-carboxyl group of one amino acid the alpha-carbon group of another amino acid.
 b. Peptide bonds have partial double bond characteristics, which limit the rotation about this bond. c. Peptide bonds are ester bonds. d. Hydrogen bonding between R-groups of amino acids gives rise to protein secondary structure. e. Only c) and d) are true.

Answer 37

b. Peptide bonds have partial double bond characteristics, which limit the rotation about this bond.

Question 38

Please select the true statement: a. One definition of an acid and a base is that an acid is a proton acceptor, and a base is a proton donor.
 b. CO2 combines with H2O to form carbonic acid, which deprotonates to form carbamate. c. The primary intracellular buffer is the phosphate buffering system. d. The primary means of CO2 transport in the body is as dissolved CO2 in the blood.

Answer 38

c. The primary intracellular buffer is the phosphate buffering system.

Question 39

Please select the true statement: a. Van der Waals attractive forces become stronger as two atoms or groups approach each other, until they reach the limit of their Van der Waals radii. b. When ∆G for a reaction is greater than zero, the reaction will proceed in the forward direction. c. HCl and KOH dissociate incompletely in aqueous solution, such that the concentrations of protonated and deprotonated acid is dependent on the pH of the solution. d. When ∆G for a reaction is zero, the reaction proceeds in the reverse direction.

Answer 39

a. Van der Waals attractive forces become stronger as two atoms or groups approach each other, until they reach the limit of their Van der Waals radii.

Question 40

Please select the true statement: a. The α2β2 tetramer becomes the predominant form of hemoglobin shortly before birth. b. The affinity of CO for hemoglobin is higher than the affinity of O2 for hemoglobin under the same conditions. c. Lowering of blood pH increases the oxygen affinity of hemoglobin d. In metabolically active tissues, CO2 is used to produce oxygen in a reaction catalyzed by carbonic anhydrase.

Answer 40

b. The affinity of CO for hemoglobin is higher than the affinity of O2 for hemoglobin under the same conditions.

Question 41

Hydrogen bonds are strongest when the hydrogen donor, the hydrogen atom and the hydrogen acceptor all lie in a straight line. a. True b. False

Answer 41

a. True

Question 42

In regard to alpha helices, hydrogen bonds that stabilize this structure are parallel to the axis of the helix and are formed between amino acids that are 3 to 4 residues apart. a. True b. False

Answer 42

a. True

Question 43

The small molecule 2,3-BPG is a poly-anionic small molecule that binds to histidine residues in hemoglobin. a. True b. False

Answer 43

a. True

Question 44

Please select the true statement: a. Alpha helices in most proteins are left-handed. b. A beta-turn is a secondary structural element representing a sharp turn that changes the direction of a peptide strand. c. The oxidation state of methemoglobin is 2+, which prevents O2 binding. d. The total energy of a system and its surroundings must increase for a reaction to be favorable.

Answer 44

b. A beta-turn is a secondary structural element representing a sharp turn that changes the direction of a peptide strand.

Question 45

Please select the false statement: a. Glycogen is a storage form of glucose polymer that is found in animal tissues. b. Hydrogen bonding is greater in glycogen and starch than it is in cellulose and chitin. c. The bonds linking sugars together to form carbohydrate polymers are called glycosidic bonds. d. Cellulose and starch are both glucose polymers. e. Glycogen is more highly branched than starch.

Answer 45

b. Hydrogen bonding is greater in glycogen and starch than it is in cellulose and chitin.

Question 46

Please select the true statement: a. Interactions between amino acid side chains determine whether any two given amino acids residues will form a peptide bond. b. Valine and methionine are hydrophobic, branched chain amino acids. c. Tryptophan, tyrosine, and phenylalanine are aromatic amino acids d. There are no true answer here.

Answer 46

c. Tryptophan, tyrosine, and phenylalanine are aromatic amino acids

Question 47

Please select the true statement: a. The small amino acid, glycine is one of the most commonly substituted amino acids. b. Protein domains are another name for motifs. c. The myoglobin protein is made of four homologous monomers. d. The pH of blood in the tissues favors the tense state of hemoglobin. e. Only a and d are true.

Answer 47

d. The pH of blood in the tissues favors the tense state of hemoglobin.

Question 48

Please select the true statement: a. The myoglobin and hemoglobin of humans are orthologs b. Leghemoglobin and human myoglobin are orthologs. c. The distal histidine is a coordination site for iron in the heme prosthetic group in myoglobin and hemoglobin. d. All the above are true e. Only b and c are true

Answer 48

b. Leghemoglobin and human myoglobin are orthologs.

Question 49

Which of the following is true? a. In a polar solution like water, hydrophobic amino acids will be more likely to be found buried in the interior of the protein rather than at the surface of the protein, facing the solvent. b. In a non-polar environment, like a membrane, hydrophobic amino acids will be more likely to be found buried in the protein rather than on the surface, facing the non-polar environment. c. Both a and b are true. d. Neither a nor b are true.

Answer 49

a. In a polar solution like water, hydrophobic amino acids will be more likely to be found buried in the interior of the protein rather than at the surface of the protein, facing the solvent.

Question 50

Which of the following sets of amino acids, left to right are hydrophobic, aromatic and basic? a. Valine; Lysine; Aspartic acid b. Lysine; Tryptophan; Asparagine c. Isoleucine; Phenylalanine; Lysine d. Leucine: Tryptophan; Valine

Answer 50

c. Isoleucine; Phenylalanine; Lysine

Question 51

During the process of transcription The RNA template is read in the 5´-3´direction. a. True b. False

Answer 51

b. False

Question 52

Select the true statement regarding weak buffers: a. Buffers are comprised of strong acids in aqueous solution. b. At the pKa of an acid, the protonated, acidic form of the acid predominates. c. Below the pKa of an acid, the conjugate base predominates. d. There are no true answers here.

Answer 52

d. There are no true answers here.

Question 53

Select the true statement: a. tRNA is an RNA template that encodes the protein sequence. b. rRNA is an adapter RNA that covalently binds to amino acids and hydrogen bonds with codons in the RNA template. c. Mutations leading to differences in DNA sequence might not lead to differences in amino acid sequence, because the genetic code is degenerate d. Eukaryotic messenger RNAs, when reverse-transcribed, will yield DNA that is identical to the genomic DNA sequence for that RNA. e. Only c and d are true.

Answer 53

c. Mutations leading to differences in DNA sequence might not lead to differences in amino acid sequence, because the genetic code is degenerate

Question 54

Which of the following is true? a. The highest order of structure seen in myoglobin is secondary structure. b. The highest order of structure of hemoglobin is tertiary structure. c. The primary and tertiary structures of beta-globin and myoglobin show high degrees of homology. d. All of the above are true.

Answer 54

c. The primary and tertiary structures of beta-globin and myoglobin show high degrees of homology.

Question 55

Which of the following is true? Please note that RNAse A and actin are homologous proteins. a. Chimp RNAse A and chimp actin are both orthologs, and paralogs. b. Chimp RNAse A and chimp actin are paralogs, and not orthologs. c. Chimp RNAse A and Human RNAse A are both paralogs, and orthologs. d. Chimp RNAse A and Human RNAse A are paralogs, not orthologs.

Answer 55

b. Chimp RNAse A and chimp actin are paralogs, and not orthologs.

Question 56

Select the true statement. a. Ionic interactions are stronger between charged molecules in non-polar than in polar solvents. b. Ionic interactions are attractive or repulsive forces between atoms with a full formal charge. c. The strength of an ionic interaction is directly proportional to the distance, r, between the ions. d. All the above are true e. Only a, and b are true.

Answer 56

e. Only a, and b are true.

Question 57

What is he pH of an aqueous solution of acetic acid when the pKa of the acid is 6.5, and the molar concentrations are: [acetic acid] = 10 mM, [acetate] = 0.1 M. a. pH= 3.5 b. pH= 8.5 c. pH= 7.5 d. pH = 4.5 e. The correct answer is not given.

Answer 57

c. pH= 7.5

Question 58

The 6 coordination sites of the iron in heme are the 4 pyrrole nitrogens, & distal and proximal histidines. a. True b. False

Answer 58

b. False

Question 59

Please select the true statement. a. The normal 3-dimensional structure of a protein is called its native state, or native conformation. b. A denatured protein is one that retains its native conformation, but is expressed at an unnatural time or place. c. Denatured proteins generally retain their normal function. d. Denaturing agents are chemicals or processes that disrupt the primary structure of a protein.

Answer 59

a. The normal 3-dimensional structure of a protein is called its native state, or native conformation.

Question 60

Please select the true statement. a. Amyloid is an insoluble aggregate of protein deposited in tissues. b. The proteins that make up an amyloid deposit are generally misfolded. c. To form an amyloid fiber, abnormal prions generally align themselves to form a continuous beta-sheet. d. All the above are true e. Only a) and b) are true.

Answer 60

d. All the above are true

Question 61

What is the pH of an aqueous solution of 0.01 nM HCl in water? a. It is approximately 1. b. It is approximately 13. c. It is approximately 7. d. The correct answer is not given.

Answer 61

c. It is approximately 7.

Question 62

Heating beef tainted with “mad cow disease”, bovine spongiform encephalitis, eliminates the prions responsible for Creutzfeldt-Jakob Disease. a. True b. False

Answer 62

b. False

Question 63

Please select the false statement. a. Ubiquitin is a tag that identifies proteins to be brought to the proteasome. b. The actual breaking of the peptide bonds of proteins by the proteasome is not done with ATP hydrolysis. c. Chaperones can limit regions available for intermolecular interaction, by masking certain regions of the protein, such as cysteine residues. d. Beta-mercaptoethanol breaks peptide bonds to denature proteins.

Answer 63

d. Beta-mercaptoethanol breaks peptide bonds to denature proteins.

Question 64

The pH of a solution is 5.8; the concentration of acid is 10mM, and the concentration of the conjugate base it 100microM. Please solve for the pKa of the acid.

Answer 64

``` pH = pKa + log [A-] / [HA] 5.8 = pKa + log 0.1 mM /10 mM 5.8 = pKa + log 10^(-1-1) 5.8 = pKa + log 10^(-2) 5.8 = pKa + -2 2+5.8 = pKa pKa = 7.8 ```

Question 65

For a given reaction under standard conditions, what is the Δ G of the reaction when Δ H = 35kJ/mole, and Δ S = 10 K/mole K. Temperature in Kelvin is 298 K.

Answer 65

ΔG = ΔH - T ΔS ΔG = 35 kJ/mole - 298K * 0.01 kJ/mole *K Δ35 kJ/mole - 2.98 kJ/mole ΔG = 32.02 kJ/mole or 32020 J/mol

Question 66

Please identify the function of the proximal histidine in hemoglobin function: a. This amino acid provides steric hindrance for the entry of CO into the heme oxygen-binding pocket. b. This amino acid makes a hydrogen bond to O2 that is bound to iron, which is in the heme ring. c. This amino acid is a coordination site for the iron, which is in the heme ring. d. Only a, and b are true e. Only a, b, and c are true.

Answer 66

c. This amino acid is a coordination site for the iron, which is in the heme ring.

Question 67

Please choose the true statement: a. The R-group of serine causes it to be a non-polar amino acid. b. Glycine is a hydrophobic amino acid. c. The histidine R-group can act like a base under physiologic conditions. d. The asparagine R-group can act as an acid under physiologic conditions.

Answer 67

c. The histidine R-group can act like a base under physiologic conditions.

Question 68

If a reaction A+B C+D has a ∆G˚ of +34.30 Joules per mole, which of the following is true? a. This reaction is thermodynamically favorable in the forward direction. b. The ∆G˚ of C+D A+B = -34.30 Joules per mole. c. The reaction A+B C+D is not at equilibrium. d. The reaction A+B C+D is exergonic. e. All the above are true. f. Only b and c are true. g. Only b and d are true.

Answer 68

f. Only b and c are true.

Question 69

Given a reaction, A+B C+D, if the concentrations of C & D increased relative to the concentrations of A & B, what will be the most likely effect on the thermodynamics of the reaction A+B C+D? a. There would be no effect on the thermodynamics. b. ∆G would decrease. c. ∆G would increase. d. The concentrations of products or reactants have no relevance to thermodynamics.

Answer 69

c. ∆G would increase.

Question 70

Given the reaction A+B C+D above with a ∆G˚ of +34.30 Joules per mole, if this reaction were coupled with another reaction, E+F C +D with a ∆G˚ of +40.50 Joules per mole, which of the following is true? a. The reaction A + B E+F has a ∆G˚ of +74.80 Joules per mole. b. The reaction A + B E+F is unfavorable in the forward direction. c. The reaction A + B E+F has a ∆G˚ of -6.20 Joules per mole. d. The reaction A + B E+F is favorable in the forward direction. e. Only a and b are true. f. Only c and d are true.

Answer 70

f. Only c and d are true.

Question 71

Which of the following is true? a. In a polar solution like water, hydrophobic amino acids will be more likely to be found buried in the interior of the protein rather than at the surface of the protein, facing the solvent. b. In a non-polar environment, like a membrane, hydrophobic amino acids will be more likely to be found buried in the protein rather than on the surface, facing the non-polar environment. c. Both a and b are true. d. Neither a nor b are true.

Answer 71

a. In a polar solution like water, hydrophobic amino acids will be more likely to be found buried in the interior of the protein rather than at the surface of the protein,

Question 72

The energy of attraction or repulsion of an ion pair is inversely proportional to the product of the charges of the ions. a. True b. False

Answer 72

b. False

Question 73

In regard to alpha helices, hydrogen bonds that stabilize this structure are parallel to the axis of the helix and are formed between amino acids that are 3 to 4 residues apart. a. True b. False

Answer 73

a. True

Question 74

The small molecule 2,3,BPG binds to histidine residues in hemoglobin, and binds more tightly to adult hemoglobin than fetal hemoglobin. a. True b. False

Answer 74

a. True

Question 75

Which of the following sets of amino acids, read 1, 2, 3 from left to right contains amino acids that are classified as: 1) basic; 2) aromatic; and 3) aliphatic, branched? a. Arginine; Lysine; Aspartic acid b. Lysine; Tryptophan; Asparagine c. Asparagine; Phenylalanine; Leucine d. Lysine; Phenylalanine; Isoleucine e. Leucine: Tryptophan; Valine

Answer 75

d. Lysine; Phenylalanine; Isoleucine

Question 76

Which of the following is true? a. The highest order of structure seen in myoglobin is secondary structure. b. The highest order of structure of hemoglobin is tertiary structure. c. The myoglobin protein is made of four homologous monomers. d. The primary and tertiary structures of beta-globin and myoglobin show high degrees of homology. e. All of the above are true. f. Only c and d are true

Answer 76

d. The primary and tertiary structures of beta-globin and myoglobin show high degrees of homology.

Question 77

Which of the following is true? Please note that RNAse A and actin are homologous proteins. a. Chimp RNAse A and Human RNAse A are paralogs, not orthologs. b. Chimp RNAse A and Human RNAse A are both paralogs, and orthologs. c. Chimp RNAse A and chimp actin are paralogs, and not orthologs. d. Chimp RNAse A and chimp actin are both orthologs, and paralogs.

Answer 77

c. Chimp RNAse A and chimp actin are paralogs, and not orthologs.

Question 78

Select the true statement: a. Buffers are weak acids that buffer most effectively at the pKa of the acid, but can buffer within one pH unit above and below the acid’s pKa. b. The phosphate buffer system is the primary blood buffer in our bodies. c. At the pKa of an acid, the acid and its conjugate base are at equimolar concentrations. d. Free amino acids can function as buffers. e. All the above are true. f. Only a, c, and d are true.

Answer 78

f. Only a, c, and d are true.

Question 79

Select the true statement: a. Secondary structures are primarily formed by hydrophobic interactions among main chain atoms. b. Amino acid R-groups fill the interior of alpha helices. c. Nucleic acid molecules are comprised of nucleotides that are linked together by phosphodiester bonds to form a polymer. d. Prolines are amino acids that are common and stabilizing in alpha helices.

Answer 79

c. Nucleic acid molecules are comprised of nucleotides that are linked together by phosphodiester bonds to form a polymer.

Question 80

Select the true statement: a. Peptide bonds have a resonance structure that is comprised of a single and double bond. b. Peptide bonds have partial double bond characteristics. c. The nature of the peptide bond is such that free rotation about the bond is negligible. d. All the above are true. e. Only b and c are true

Answer 80

d. All the above are true.

Question 81

Select the false statement: a. Motifs are recognized by the presence of secondary structural elements that follow one another directly in a specific pattern b. Motifs such as helix-turn-helix can be used to characterize the function and classification of proteins. c. Coils and loops are secondary structural elements. d. The primary structure of a protein is the amino acid content of that protein.

Answer 81

d. The primary structure of a protein is the amino acid content of that protein.

Question 82

Lipids are macromolecules that act as a fuel source, provide structure & act as signaling molecules. a. True b. False

Answer 82

a. True

Question 83

The process of transcription does not require a primer. a. True b. False

Answer 83

a. True

Question 84

Select the true statement. a. Ionic interactions are stronger between charged molecules in polar solvents. b. Ionic interactions are attractive or repulsive forces between atoms with a full formal charge. c. The strength of ionic interactions is directly proportional to the dielectric constant of the solution. d. The strength of an ionic interaction is inversely proportional to the distance, r, between the ions. e. All the above are true. f. Only a and b are true. g. Only b and d are true.

Answer 84

g. Only b and d are true.

Question 85

Identify the pH of an aqueous solution of acetic acid. The pKa of the acid is 4.5, and the molar concentrations are: [acetic acid] = 10 mM, [acetate] = 0.1 M. a. pH= 9.2 b. pH= 11 c. pH= 7 d. pH = 7.2 e. The correct answer is not given.

Answer 85

e. The correct answer is not given.

Question 86

What is the pH of an aqueous solution of 0.01 nM KOH in water? a. It is approximately 1. b. It is approximately 13. c. It is approximately 7. d. The correct answer is not given.

Answer 86

c. It is approximately 7.

Question 87

Which is not one of the four most prevalent elements in living things: a. Hydrogen b. Potassium c. Nitrogen d. Oxygen

Answer 87

b. Potassium

Question 88

Select the true statement: a. tRNA is an RNA template that encodes the protein sequence. b. rRNA is an adapter RNA that covalently binds to amino acids and hydrogen bonds with codons in the RNA template. c. Eukaryotic messenger RNAs, when reverse-transcribed, will yield DNA that is identical to the genomic DNA sequence for that RNA. d. Mutations leading to differences in DNA sequence might not lead to differences in amino acid sequence, because the genetic code is degenerate. e. Only c and d are true.

Answer 88

d. Mutations leading to differences in DNA sequence might not lead to differences in amino acid sequence, because the genetic code is degenerate.

Question 89

Select the true statement regarding weak buffers: a. Buffers are strong acids that can buffer within one pH unit above and below the acid’s pKa. b. At the pKa of an acid, the protonated, acidic form of the acid predominates. c. The phosphate buffer system is the primary intracellular buffer in our bodies. d. There are no true answers here.

Answer 89

c. The phosphate buffer system is the primary intracellular buffer in our bodies.

Question 90

During the process of transcription The RNA template is read in the 5´-3´direction. a. True b. False

Answer 90

b. False

Question 91

Carbon dioxide in the blood is carried predominantly as bicarbonate ions, and to a lesser extent as dissolved CO2 or covalently linked to hemoglobin as carbamate in carboxyhemogobin a. True b. False.

Answer 91

a. True

Question 92

The pH of blood in the tissues favors the tense state of hemoglobin. a. True b. False.

Answer 92

a. True

Question 93

Please solve for pKa when pH=7.2, and the concentrations of H2PO4– = 1 mM and HPO42– = 100 mM

Answer 93

``` pH = pKa + log [A-] / [HA] [HA] = [H2PO4–] = 1mM [HA] = [HPO4^2–] = 100mM 7.2 = pka + log 100mM/1mM 7.2 = pKa + 2 5.2 = pKa ```

Question 94

Please write the reaction catalyzed by carbonic anhydrase, remember to include all reactants and products.

Answer 94

H2O + CO2 yields H2CO3

Question 95

Under physiologic conditions, Cys-Cys bonds and Lys-Asp bonds can form between the R-groups of these amino acids. Please describe the major difference between these two bonds.

Answer 95

Cys-Cys bonds are covalent ; Lys-Asp bonds in aqueous solution at physiologic pH are ionic

Question 96

Please choose the true statement: a. The four most prevalent elements in living things are hydrogen, carbon, oxygen, and phosphorus. b. The major attractive force that is formed between two methyl groups is fixed-dipole, dipole. c. The attractive bond energy between two ions is directly proportional to the magnitude of the charge on the ions. d. Hydrophobic interactions arise because of charge repulsion between the solution and the hydrophobic solute.

Answer 96

c. The attractive bond energy between two ions is directly proportional to the magnitude of the charge on the ions.

Question 97

Please choose the true statement: a. Our bodies represent closed systems. b. The buffering capacity of a buffering system is greatest at the pKa of the conjugate acid. c. Each buffer has one optimal buffering range. d. The prominent buffering system of the cell is the carbonic acid, bicarbonate buffering system.

Answer 97

b. The buffering capacity of a buffering system is greatest at the pKa of the conjugate acid.

Question 98

The First Law of Thermodynamics says that the energy of any system is constant. a. True b. False

Answer 98

b. False

Question 99

Please choose the true statement: a. The entropy of the universe always decreases. b. ∆ S of the universe must always be a negative number. c. ∆G˚’ represents the free energy of a system in aqueous solution at pH 7 and at standard temperature and pressure. d. All the above are true

Answer 99

c. ∆G˚’ represents the free energy of a system in aqueous solution at pH 7 and at standard temperature and pressure.

Question 100

Please choose the true statement: a. Glycine is in the L-configuration, but proline is not, because it is an imide. b. Aspartate is a basic amino acid because its guanidinium group can pick up a proton at physiologic pH to become protonated. c. Of the 20 amino acids found in proteins, those classified as basic, have a full formal positive charge at physiologic pH. d. All the above are true. e. Only a and c are true.

Answer 100

c. Of the 20 amino acids found in proteins, those classified as basic, have a full formal positive charge at physiologic pH.

Question 101

Please choose the correct groupings: where P=protein, C= carbohydrates, N = nucleic acids and L = Lipids. a. Form covalently linked polymeric structures: P, C, N, L b. Found in the cell membrane, either as primary constituents of the membrane itself or as surface structures: P, C, L c. Provide energy either through catabolism or through hydrolysis of high energy bonds: P, C, N, L d. All the above are true e. Only b and c are true

Answer 101

e. Only b and c are true

Question 102

The pI of a protein is the pH at which the protein has no charge, as all amino acid side chains and both the terminal alpha-carboxy and -amino groups are neutral in charge. a. True b. False

Answer 102

b. False

Question 103

The nitrogenous bases in DNA are Cytosine Guanine Thymine and Uracil. a. True b. False

Answer 103

b. False

Question 104

Please choose the true statement such that an ionic salt bridge can be formed between the side chains of the amino acids listed at the stated pH a. Arginine and Histidine, at pH 10 b. Histidine and Aspartate, at pH 3 c. Glutamine and Histidine, at pH 8 d. Proline and Lysine at pH 7 e. None of the above can form a salt bridge at these described pH values.

Answer 104

e. None of the above can form a salt bridge at these described pH values

Question 105

Two ions in an ionic bond in H2O have a bond energy of - 5.9 kJmol-1. Which of the following is true: a. In hexane, at the same distance, this bond energy would have a greater value than 5.9 and be positive. b. In hexane, at the same distance, this bond energy would have a greater value than 5.9 and be negative. c. If these two ions were left in solution but somehow moved further apart, the bond energy between them would become more negative. (a higher value than 5.9 and still negative) d. If the one of these ions were switched to have an opposite charge of the same magnitude, and both ions remained in water and at the same distance, the bond energy would be +5.9 kJmol-1. e. Only a, c and d are true f. Only b and d are true.

Answer 105

f. Only b and d are true.

Question 106

Please choose the true statement: a. The pI of a protein is the pH at which the protein as a whole is neutral in charge.
 b. The pI is the pH at which all of the amino acids comprising that protein are neutrally charged c. The pI of a protein is the pH at which all of its amino acid R-groups are deprotonated. d. There are no true answers here.

Answer 106

a. The pI of a protein is the pH at which the protein as a whole is neutral in charge.

Question 107

Select the correct statement to finish this sentence correctly : In describing the genetic code: a. codons in the transcript are overlapping sets of 3 bases corresponding to 1 amino acid. b. one codon can correspond to more than one amino acid. c. one amino acid can be coded by two or more codons. d. each of the 64 possible combinations of three bases corresponds to a particular amino acid. e. Both b and d are true. f. Both c and d are true.

Answer 107

c. one amino acid can be coded by two or more codons.

Question 108

Which of the following is NOT one of the weak, non-covalent forces frequently involved in biomolecular interactions? a. Disulfide bonds b. Hydrophobic interactions c. Ionic interactions d. Hydrogen bonds

Answer 108

a. Disulfide bonds

Question 109

Sickle cell anemia, Hs, confers a survival advantage in persons: a. Homozygous for Hs b. Heterozygous for Hs c. Either Homozygous or Heterozygous for Hs d. This allele does not confer any advantage.

Answer 109

b. Heterozygous for Hs

Question 110

Which of the following is false?
 a. In aqueous solution, proteins are surrounded by a hydration shell of water molecules b. In aqueous solution, proteins form hydrogen bonds with water molecules.
 c. In aqueous solution, polar amino acids are most commonly on the outside of a protein, 
and interact with the solution.
 d. In a lipid environment, and in an aqueous environment, the amino acids with 
hydrophobic side chains are most commonly buried on the inside of the protein rather than the outside.

Answer 110

d. In a lipid environment, and in an aqueous environment, the amino acids with 
hydrophobic side chains are most commonly buried on the inside of the protein rather than the outside.

Question 111

Please choose the true statement: a. The normal 3-dimensional structure of a protein is called its primary structure. b. A denatured protein is one that has become proteolyzed. c. Denatured proteins generally do not show loss of normal function. d. Denaturing agents can often disrupt the weak non-covalent interactions in a protein. e. Only a, b and c are true

Answer 111

d. Denaturing agents can often disrupt the weak non-covalent interactions in a protein.

Question 112

Beta-mercaptoethanol is an reducing agent used by Christian Anfinsen to disrupt ionic bonds a. True b. False

Answer 112

b. False

Question 113

Free amino acids cannot have an isoelectric point. a. True b. False

Answer 113

b. False

Question 114

Hemoglobin has a low affinity for oxygen under conditions found in the peripheral tissues (tissues other than the lungs, arteries, arterioles) What are the conditions cause hemoglobin to have a low affinity for oxygen?
 a. High pH and Low CO2 b. Low pH and High CO2 c. High pH and High CO2 d. Low pH and Low CO2

Answer 114

b. Low pH and High CO2

Question 115

Please choose the true statement: a. The four classes of macromolecules are carbohydrates, vitamins, lipids, and proteins. b. All amino acids found in living organisms are L-stereoisomers. c. When proteins are comprised of single peptide chains, they are said to have secondary structure, but they do not have tertiary structure; this is reserved for multimeric proteins. d. There are no true statements here.

Answer 115

d. There are no true statements here

Question 116

Please choose the false statement: a. Kuru is a human disease caused by degeneration of brain tissue through accumulation of mis-folded proteins. b Amyloid fibrils are generally comprised of misfolded subunits that are high in beta sheet composition. c. Amyloids are readily accessible to cellular proteases. d. Alzheimer’s disease is a disease in which amyloid plaques are formed.

Answer 116

c. Amyloids are readily accessible to cellular proteases.

Question 117

Please choose the true statement: a. In protein folding, chaperones most often work by making hydrophobic regions of the protein more accessible to the aqueous solution. b. Chaperone numbers increase during heat stress and are also known as heat shock proteins. c. One method by which the human papilloma virus causes cellular proliferation is by causing p53 to become a target for ubiquitination. d. Only a and c are true e. Only b and c are true

Answer 117

e. Only b and c are true

Question 118

Please choose the tri-peptide that from amino to carboxy terminus is basic; aromatic; branched chain a. Asn, Arg, Val b. His, Phe, Ser c. Lys, Trp, Ile d. Arg, Ile, Val

Answer 118

c. Lys, Trp, Ile

Question 119

All 15 essential amino acids cannot be synthesized at all by the human body and must be taken in through the diet. a. True b. False

Answer 119

b. False

Question 120

Interactions between amino acid side chains determine whether any two given amino acids residues will form a peptide bond. a. True b. False

Answer 120

b. False

Question 121

RNA is used as a template to make DNA during transcription. a. True b. False

Answer 121

b. False

Question 122

Please name one conservative substitution for the following; do not use the same amino acid twice: a. Arg b. Leu c. Asp d. Thr e. Asn

Answer 122

a. Arg: pos charged AA b. Leu: Branced AA c. Asp: glu or gln, asn d. Thr: ser e. Asn: gun, asp, glu

Question 123

Please solve for pKa if pH = 4.5, the concentration of A- is 10 mM, the concentration of HA is 100 μM.

Answer 123

pH = pKa + log [A-]/[HA] 4. 5 = x + log (10mM/0.1mM) 4. 5 = x+ log (10+1 mM/ 10-1 mM) 4. 5 = x+ log 10 (+1-(-1) So 4.5 x plus the log of 102, and all a log is, is the number to which 10 is raised. so the log of 102 = 2 4. 5 = X + 2 therefore 2.5 = X

Question 124

4)  Please solve for ∆G when ∆S = 100 J/mole K, ∆T= 298 K, and ∆H = 0.1kJ/mole

Answer 124

∆G = ∆H-T∆S ∆G = ∆H-T∆S where T is in Kelvin. Put these in the same terms. kilo-Joule works for me. So ∆S is 0.1 kJ mole-1 K-1 ∆G= 0.1 kJ mole-1 - 298 K * 0.1 kJ mole-1 K-1 ∆G= 0.1 kJ mole-1 - 29.8 kJ mole-1 = -29.7 kJ mole-1

Question 125

 Please identify the globin composition of: Adult hemoglobin Fetal hemoglobin

Answer 125

Adult hemoglobin: alpha2 Beta 2 | Fetal hemoglobin: alpha2 Gamma2

Question 126

What is the role of the distal histidine in hemoglobin function?

Answer 126

The distal His helps to regulate the entry and exit form the Fe2+ O2 binding site. Large molecules like CO2 have a harder time getting in, and O2 is stabilized to leave as O2 and not superoxide, O2-. You had to mention both por