173 - 240

Question 1

Lysine at low pH (pH=1) have….

Select one:
a. no charge at the a-carboxyl group, and two positive charges at the a-and e-amino groups.
b. a negative charge on the a-carboxyl group, a positive charge on the a- amino group and no charge on the e-amino group.
c. a negative charge on the a-carboxyl group, and two positive charges at the a-and e-amino groups.
d. no charge at the a-carboxyl group, a positive charge on the a-amino group and no charge on the e-amino group.
e. no charge at the a-carboxyl group, no charge on the a-amino group and a positive charge on the e-amino group.

Answer 1

a. no charge at the a-carboxyl group, and two positive charges at the a-and e-amino groups.

Question 2

Which of the following statements are true for the isoelectric form of amino acids?

Select one or more:
a. All the naturally occurring amino acids have one positive and one negative charges.
b. The a-amino group of all the naturally occurring amino acids has a positive charge.
c. The a-carboxyl group of all the naturally occurring amino acids has a negative charge.

Answer 2

a. All the naturally occurring amino acids have one positive and one negative charges.
b. The a-amino group of all the naturally occurring amino acids has a positive charge.
c. The a-carboxyl group of all the naturally occurring amino acids has a negative charge.

Question 3

At neutral pH a tetrapeptide of glycylalanylarginylglutamate has…

Select one:
a. two positive and three negative charges
b. two positive and one negative charges
c. one positive and one negative charges
d. one positive and two negative charges
e. two positive and two negative charges

Answer 3

e. two positive and two negative charges

Question 4

Of the 20 standard amino acids, only ___________ is not optically active. The reason is that its side chain ___________.

Select one:
a. alanine; is a simple methyl group
b. glycine; is a hydrogen atom.
c. glycine; is unbranched.
d. lysine; contains only nitrogen.
e. proline; forms a covalent bond with the amino group.

Answer 4

b. glycine; is a hydrogen atom.

Question 5

The arginyllysylaspartate tripeptide has

Select one or more:
a. its isoelectric point at basic pH.
b. three positive and two negative charges at neutral pH.
c. two positive and two negative charges at its isoelectric point.

Answer 5

a. its isoelectric point at basic pH.
b. three positive and two negative charges at neutral pH.
c. two positive and two negative charges at its isoelectric point.

Question 6

The chirality of an amino acid results from the fact that its a—carbon…

Select one:
a. is bonded to four different chemical groups.
b. is a carboxylic acid.
c. is symmetric.
d. is in the L absolute configuration in naturally occurring proteins.
e. has no net charge.

Answer 6

a. is bonded to four different chemical groups.

Question 7

Which of the following statements about formation of cystine is correct?

Select one:
a. There is a peptide linkage between two cysteines.
b. Two –CH2–SH groups are oxidized to form a –CH2–S–S–CH2– disulfide bridge between two cysteines
c. Two cystines are released when a –CH2–S–S–CH2– disulfide bridge is reduced to –CH2–SH.
d. Cystine is an example of a nonstandard amino acid, derived by linking two different standard amino acids.
e. Cystine is formed by the oxidation of the carboxylic acid group on cysteine.

Answer 7

b. Two –CH2–SH groups are oxidized to form a –CH2–S– S–CH2– disulfide bridge between two cysteines

Question 8

In a highly basic solution, pH = 13, the dominant form of glycine is:

Select one:
a. NH2–CH2–COO-.
b. NH2–CH2–COOH.
c. NH3+–CH2–COOH.
d. NH3+–CH2–COO-.
e. NH2–CH3+–COO-.

Answer 8

a. NH2–CH2–COO-.

Question 9

For amino acids with neutral side chain, at any pH below the pI of the amino acid, the population of amino acids in solution will:

Select one:
a. have a net positive charge.
b. have no charged groups.
c. have no net charge.
d. have positive and negative charges in equal concentration.
e. have a net negative charge

Answer 9

a. have a net positive charge.

Question 10

An octapeptide composed of four repeating glycylalanyl units has:

Select one:
a. a single free amino group on an alanyl residue.
b. two free amino and two free carboxyl groups.
c. a single free amino group on a glycyl residue and a single free carboxyl group on an alanyl residue
d. two free carboxyl groups, both on glycyl residues.
e. a single free amino group on an alanyl residue and a single free carboxyl group on a glycyl residue.

Answer 10

c. a single free amino group on a glycyl residue and a single free carboxyl group on an alanyl residue

Question 11

At the isoelectric pH of a tetrapeptide:

Select one:
a. there are four ionic charges
b. the amino and carboxyl termini are not charged.
c. two internal amino acids of the tetrapeptide cannot have ionizable R groups.
d. the total net charge is zero.
e. only the amino and carboxyl termini contribute charge.

Answer 11

d. the total net charge is zero.

Question 12

Which of the following describes the overall three-dimensional folding of a polypeptide?

Select one:
a. primary structure
b. secondary structure
c. tertiary structure
d. quaternary structure
e. none of the above

Answer 12

c. tertiary structure

Question 13

By adding SDS (sodium dodecyl sulfate) during the electrophoresis of proteins, it is possible to:

Select one:
a. preserve a protein’s native structure and biological activity
b. separate proteins exclusively on the basis of molecular weight.
c. determine a protein’s isoelectric point.
d. determine the amino acid composition of the protein.
e. determine an enzyme’s specific activity.

Answer 13

b. separate proteins exclusively on the basis of molecular weight.

Question 14

Specific enzyme activity:

Select one:
a. is the enzyme activity (expressed as units'') of a specific protein. b. is the enzyme activity (enzyme asunits’’) in a milligram of protein.
c. is the enzyme activity (expressed as ``units’’) in a mol of protein.
d. refers to proteins other than enzymes.
e. refers only to purified proteins.

Answer 14

b. is the enzyme activity (enzyme as ``units’’) in a milligram of protein.

Question 15

The backbone of two amino acid residues in a protein can be described as (where Ca is C-alpha):
Select one:
a. Ca–C–N–Ca–C–N
b. Ca–N–Ca–C–Ca–N–Ca–C
c. Ca–N–C–C–N–Ca–
d. C–N–Ca–Ca–C–N
e. Ca–Ca–C–N–Ca–Ca–C

Answer 15

a. Ca–C–N–Ca–C–N

Question 16

Which of the following bond-pairs within a peptide backbone show free rotation around both bonds?

Select one:
a. C¬O and N–C
b. N–Ca and N–C
c. Ca–C and N–Ca
d. C¬O and N–C?
e. N–C and Ca–C

Answer 16

c. Ca–C and N–Ca

Question 17

In the a helix the hydrogen bonds:

Select one:
a. occur only between some of the amino acids of the helix.
b. occur mainly between electronegative atoms of the R groups.
c. are perpendicular to the axis of the helix.
d. occur mainly between electronegative atoms of the backbone.
e. occur only near the amino and carboxyl termini of the helix.

Answer 17

d. occur mainly between electronegative atoms of the backbone.

Question 18

In a helix, the R groups on the amino acid residues:
Select one:
a. stack within the interior of the helix.
b. generate the hydrogen bonds that form the helix.
c. are located outside of the helix spiral.
d. cause only right-handed helices to form.
e. alternate between the outside and the inside of the helix.

Answer 18

c. are located outside of the helix spiral.

Question 19

A D-amino acid would interrupt an a helix made of L-amino acids. Another naturally occurring constraint on the formation of an a helix is the presence of:

Select one:
a. a negatively charged Arginine residue.
b. a positively charged Lysine residue.
c. two Glycine residues side by side.
d. a nonpolar residue near the carboxyl terminus. e. a Proline residue.

Answer 19

e. a Proline residue.

Question 20

Thr and/or Leu residues tend to disrupt an a-helix when they occur next to each other in a protein because:

Select one:
a. of the possible covalent interactions between the Thr and/or Leu side chains.
b. both amino acids are highly hydrophobic.
c. the R group of neither amino acid can form a hydrogen bond.
d. of electrostatic repulsion between the Thr and/or Leu side chains.
e. of steric hindrance between the bulky Thr and/or Leu side chains.

Answer 20

e. of steric hindrance between the bulky Thr and/or Leu side chains.

Question 21

Amino acid residues commonly found at the end of b turn are:

Select one:
a. Pro and Gly.
b. Ala and Gly.
c. two Cys.
d. hydrophobic.
e. those with ionized R groups.

Answer 21

b. Ala and Gly.

Question 22

A sequence of amino acids in a certain protein is found to be -Ser-Gly-Pro- Gly-. The sequence is most probably part of:

Select one:
a. b turn.
b. parallel b sheet.
c. a helix.
d. a–sheet.
e. antiparallel b sheet.

Answer 22

a. b turn.

Question 23

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:

Select one:
a. restricted to only about seven of the twenty standard amino acids found in proteins
b. always side by side.
c. generally on different polypeptide strands.
d. generally near the polypeptide chain’s amino terminus or carboxyl terminus.
e. generally near each other in sequence.

Answer 23

e. generally near each other in sequence.

Question 24

Which of the following statements is false?

Select one:
a. a-keratin is a protein in which the polypeptides are mainly in the a-helix conformation
b. Silk fibroin is a protein in which the polypeptide is almost entirely in the b conformation.
c. Collagen is a protein in which the polypeptides are mainly in the a-helix conformation
d. Gly residues are particularly abundant in collagen.
e. Mutations in collagen have been shown to be responsible for some human diseases

Answer 24

c. Collagen is a protein in which the polypeptides are mainly in the a-helix conformation

Question 25

To alter the shape of the a-keratin chains–as in hair waving– the a-keratin chains have undergone one chemical step resulting the conversion of disulfide bridges to Cysteine. What subsequent steps are required?

Select one:
a. chemical reduction and then chemical oxidation
b. chemical oxidation and then shape remodeling
c. shape remodeling and then chemical reduction
d. shape remodeling and then chemical oxidation
e. chemical reduction and then shape remodeling

Answer 25

d. shape remodeling and then chemical oxidation

Question 26

Which of the following statements about oligomeric proteins is false?

Select one:
a. Some subunits may have nonprotein prosthetic groups.
b. All subunits must be identical.
c. Contain more than one N-terminals
d. Some oligomeric proteins can further associate into large fibres.
e. Many have regulatory roles.

Answer 26

b. All subunits must be identical.

Question 27

Which of the following statements about proteins is false?

Select one:
a. Nonpolar amino acid side chains are mostly located on the surface of the water-soluble proteins.
b. Most of the globular proteins are compact.
c. Proteins are sometimes conjugated with carbohydrates or fats.
d. Many proteins have more than one polypeptide.
e. proteins consist of amino acids linked by peptide bonds.

Answer 27

a. Nonpolar amino acid side chains are mostly located on the surface of the water- soluble proteins.

Question 28

Which of the following statements about proteins is true?

Select one:
a. Proteins that contain a-helical regions never contain b–sheets
b. Proteins are generally very loosely structured.
c. In water-soluble proteins, hydrophobic
(nonpolar) amino acid residues are generally buried and not exposed to water.
d. Detergents (such as sodium dodecyl sulfate, SDS) will not affect the structure of a protein that contains disulfide (–S–S–) bonds.
e. Hydrogen bonds are not important in the structure of proteins.

Answer 28

c. In water-soluble proteins, hydrophobic
(nonpolar) amino acid residues are generally buried and not exposed to water.

Question 29

When oxygen binds to a heme-containing protein, the two open coordination bonds of Fe2+ are occupied by:

Select one:
a. two O2 molecules.
b. two O atoms.
c. one O2 molecule and one heme atom.
d. one O2 molecule and one amino acid atom.
e. one O atom and one amino acid atom.

Answer 29

e. one O atom and one amino acid atom.

Question 30

In the binding of oxygen to myoglobin, the relationship between the concentration of oxygen and the fraction of binding sites occupied can best be described as:

Select one:
a. random.
b. sigmoidal.
c. linear with a positive slope.
d. linear with a negative slope.
e. hyperbolic.

Answer 30

e. hyperbolic.

Question 31

Myoglobin and the subunits of hemoglobin have:

Select one:
a. no obvious structural relationship.
b. very similar primary structures, but different tertiary structures.
c. very similar primary and tertiary structures.
d. very different primary and tertiary structures.
e. very similar tertiary structures, but different primary structures.

Answer 31

e. very similar tertiary structures, but different primary structures.

Question 32

In haemoglobin, the transition from T state to R state (low to high affinity) is triggered by:

Select one:
a. subunit dissociation.
b. oxygen binding.
c. Fe2+ binding.
d. heme binding.
e. subunit association.

Answer 32

b. oxygen binding.

Question 33

Which of the following is not correct concerning 2,3-bisphosphoglycerate (BPG)?

Select one:
a. It is normally found associated with the haemoglobin molecules that are extracted from red blood cells.
b. It decreases the affinity of haemoglobin for oxygen.
c. It binds to the heme groups of haemoglobin.
d. It is an allosteric modulator.
e. It binds with lower affinity to foetal haemoglobin than to adult haemoglobin

Answer 33

c. It binds to the heme groups of haemoglobin.

Question 34

The amino acid substitution of Val for Glu in Hemoglobin S results in aggregation of the protein. Which interactions are formed between the molecules in this case?

Select one:
a. hydrophobic
b. ionic
c. hydrogen bonding
d. covalent
e. disulfide

Answer 34

a. hydrophobic

Question 35

An allosteric interaction between a ligand and a protein is one in which:

Select one:
a. two different ligands can bind to the same binding site.
b. the binding of the ligand to the protein is covalent.
c. multiple molecules of the same ligand can bind to the same binding site.
d. the binding of a molecule to a binding site affects the binding of an additional molecule to the same site.
e. the binding of a molecule to its binding site affects the binding properties of another site on the same protein

Answer 35

e. the binding of a molecule to its binding site affects the binding properties of another site on the same protein

Question 36

Which of the following statements is true of enzyme catalysts?

Select one:
a. They increase the equilibrium constant for a reaction, thus favoring product formation.
b. To be effective they must be present at the same concentration as their substrates.
c. They lower the activation energy for the conversion of substrate to product.
d. They increase the stability of the product of a desired reaction by allowing ionizations, resonance, and isomerizations not normally available to substrates.
e. They bind to substrates but are never covalently attached to substrate or product.

Answer 36

c. They lower the activation energy for the conversion of substrate to product.

Question 37

Which of the following statements is false?

Select one:
a. At the end of an enzyme-catalyzed reaction, the functional enzyme becomes available to catalyze the reaction again.
b. For S P, a catalyst shifts the reaction equilibrium to the right.
c. Substrate binds to an enzyme’s active site.
d. A reaction may not occur at a detectable rate even though it has a favourable equilibrium
e. Lowering the temperature of a reaction will lower the reaction rate

Answer 37

b. For S P, a catalyst shifts the reaction equilibrium to the right.

Question 38

Enzymes differ from other catalysts in that enzymes:

Select one:
a. usually display specificity toward a single reactant.
b. fail to influence the equilibrium point of the reaction.
c. form an activated complex with the reactants.
d. lower the activation energy of the reaction catalyzed.
e. are not consumed in the reaction.

Answer 38

a. usually display specificity toward a single reactant.

Question 39

The concept of “induced fit” refers to the fact that:

Select one:
a. enzyme-substrate binding induces an increase in the reaction entropy, thereby catalyzing the reaction.
b. when a substrate binds to an enzyme, the enzyme induces a loss of water (desolvation) from the substrate.
c. substrate binding may induce a conformational change in the enzyme, which then brings catalytic groups into proper orientation.
d. enzyme specificity is induced by enzyme-substrate binding.
e. enzyme-substrate binding induces movement along the reaction coordinate to the transition state.

Answer 39

c. substrate binding may induce a conformational change in the enzyme, which then brings catalytic groups into proper orientation.

Question 40

The benefit of measuring the initial rate (V) of a reaction, is that at the beginning of a reaction:

Select one:
a. V=Vmax
b. changes in [S] are negligible, so [S] can be assumed as constant.
c. the effects of allosteric modulators become negligible
d. KM is the lowest at zero time, so the affinity to the substrate is maximal.
e. changes in [ES] will not influence the rate.
f. varying [S] has no effect on V.

Answer 40

b. changes in [S] are negligible, so [S] can be assumed as constant.

Question 41

Which of the following statements about a plot of V vs. [S] for an enzyme that
follows Michaelis-Menten kinetics is false?

Select one:
a. The y-axis is a rate term with units of mmol/min.
b. The shape of the curve is a hyperbola.
c. At very high [S], the velocity curve becomes a horizontal line that intersects the y-axis at KM.
d. As [S] increases, the initial velocity of reaction(V) also increases.
e. KM is the [S] at which V=1/2 Vmax.
f. At high substrate concentrations the reaction is of zero order

Answer 41

c. At very high [S], the velocity curve becomes a horizontal line that intersects the y-axis at KM.

Question 42

The Lineweaver-Burk plot is used to:

Select one:
a. illustrate the effect of temperature on an enzymatic reaction.
b. solve, graphically, for the rate of an enzymatic reaction at infinite substrate concentration.
c. determine the equilibrium constant for an enzymatic reaction.
d. solve, graphically, for the ratio of products to reactants for any starting substrate concentration.
e. extrapolate for the value of reaction rate at infinite enzyme concentration.

Answer 42

b. solve, graphically, for the rate of an enzymatic reaction at infinite substrate concentration.

Question 43

The double-reciprocal transformation of the Michaelis-Menten equation, also called the Lineweaver-Burk plot, is given by 1/V = KM /(Vmax[S]) + 1/Vmax. To determine KM from a double-reciprocal plot, you would:

Select one:
a. multiply the reciprocal of the x-axis intercept by -1.
b. take the reciprocal of the x-axis intercept.
c. take the x-axis intercept where V
d. 1/2 Vmax.
e. take the reciprocal of the y-axis intercept.
f. multiply the reciprocal of the y-axis intercept by -1

Answer 43

a. multiply the reciprocal of the x-axis intercept by -1.
d. 1/2 Vmax.

Question 44

For enzymes in which the slowest (rate-limiting) step is the reaction k2 ES ®
PKM becomes equivalent to:
Select one:
a. kcat.
b. the turnover number.
c. the dissociation constant(Kd) for the ES complex.
d. the [S] where V
e. Vmax.
f. the maximal velocity.

Answer 44

c. the dissociation constant(Kd) for the ES complex.
e. Vmax.

Question 45

To calculate the turnover number of an enzyme you need to know the:

Select one or more:
a. initial velocity of the catalyzed reaction at low [S].
b. initial velocity of the catalyzed reaction at [S]&raquo_space; KM.
c. KM for the substrate.
d. enzyme concentration.

Answer 45

b. initial velocity of the catalyzed reaction at [S]&raquo_space; KM.
d. enzyme concentration.

Question 46

In a plot of l/V against 1/[S] for an enzyme-catalyzed reaction, the presence of a competitive inhibitor will alter the:

Select one:
a. curvature of the plot.
b. intercept on the l/V axis.
c. Vmax.
d. intercept on the l/[S] axis.
e. pK of the plot.

Answer 46

d. intercept on the l/[S] axis.

Question 47

In competitive inhibition, an inhibitor:

Select one:
a. binds only to the ES complex.
b. binds at several different sites on an enzyme.
c. binds reversibly at the active site.
d. binds covalently to the enzyme.
e. lowers the characteristic Vmax of the enzyme.

Answer 47

c. binds reversibly at the active site.

Question 48

Which of these statements about enzyme-catalyzed reactions is false?

Select one:
a. The activation energy for the catalyzed reaction is the same as for the uncatalyzed reaction, but the equilibrium constant is more favorable in the enzyme-catalyzed reaction.
b. At saturating levels of substrate, the rate of an enzyme-catalyzed reaction is proportional to the enzyme concentration.
c. The Michaelis-Menten constant (Km) equals the [S] at which V = 1/2 Vmax.
e. If enough substrate is added, the normal Vmax of a reaction can be attained even in the presence of a competitive inhibitor.
f. The rate of a reaction decreases steadily with time as substrate is depleted.

Answer 48

a. The activation energy for the catalyzed reaction is the same as for the uncatalyzed reaction, but the equilibrium constant is more favorable in the enzyme-catalyzed reaction.
c. The Michaelis-Menten constant (Km) equals the [S] at which V = 1/2 Vmax.

Question 49

Vmax for an enzyme-catalyzed reaction:

Select one:
a. is unchanged in the presence of a uncompetitive inhibitor.
b. increases in the presence of a competitive inhibitor.
c. is twice the rate observed when the concentration of substrate is equal to the KM
d. generally increases when pH increases.
e. is limited only by the amount of substrate supplied.

Answer 49

c. is twice the rate observed when the concentration of substrate is equal to the KM

Question 50

Enzyme X exhibits maximum activity at pH = 6.9. X shows a fairly sharp decrease in its activity when the pH goes much lower than 6.4. One likely interpretation of this pH activity is that:

Select one:
a. the enzyme is found in gastric secretions
b. a Lysine residue on the enzyme is involved in the reaction.
c. a Glutamate residue on the enzyme is involved in the reaction.
d. a Histidine residue on the enzyme is involved in the reaction.
e. the enzyme has a metallic cofactor.

Answer 50

d. a Histidine residue on the enzyme is involved in the reaction.

Question 51

A good transition-state analog:

Select one:
a. binds to the enzyme more tightly than the substrate.
b. binds covalently to the enzyme.
c. is too unstable to isolate.
d. binds very weakly to the enzyme.
e. does not react with the native enzyme

Answer 51

a. binds to the enzyme more tightly than the substrate.

Question 52

A transition-state analog:

Select one:
a. resembles the active site of general acid-base enzymes.
b. typically reacts more rapidly with an enzyme than the normal substrate.
c. is less stable when binding to an enzyme than the normal substrate.
d. stabilizes the transition state for the normal enzyme-substrate complex.
e. resembles the transition-state structure of the normal enzyme-substrate complex

Answer 52

e. resembles the transition-state structure of the normal enzyme-substrate complex

Question 53

Both water and glucose share an –OH that can serve as a substrate for a reaction with the terminal phosphate of ATP catalyzed by hexokinase. Glucose, however, is about a million times more reactive as a substrate than water. The best explanation is that:

Select one:
a. the larger glucose binds better to the enzyme; it induces a conformational change in hexokinase that brings active-site amino acids into position for catalysis.
b. glucose has more –OH groups per molecule than does water.
c. water normally will not reach the active site because it is hydrophobic.
d. water and ATP compete for the active site resulting in a competitive inhibition of the enzyme.
e. the –OH group of water is attached to an inhibitory H atom while the glucose –OH group is attached to C.

Answer 53

a. the larger glucose binds better to the enzyme; it induces a conformational change in hexokinase that brings active-site amino acids into position for catalysis.

Question 54

Which of the following statements about allosteric control of enzymatic activity is false?

Select one:
a. Allosteric proteins are generally composed of several subunits.
b. Heterotropic allosteric effectors compete with substrate for binding sites.
c. Binding of the effector changes the conformation of the enzyme molecule.
d. An effector may either inhibit or activate an enzyme.
e. Homotropic allosteric effectors do not have a separate binding site.

Answer 54

b. Heterotropic allosteric effectors compete with substrate for binding sites.

Question 55

A small molecule that decreases the activity of an enzyme by binding to a site other than the catalytic site is termed a:

Select one:
a. stereospecific agent.
b. alternative inhibitor.
c. allosteric inhibitor.
d. competitive inhibitor.
e. transition-state analog.

Answer 55

c. allosteric inhibitor.

Question 56

How is trypsinogen converted to trypsin?

Select one:
a. Proteolysis of trypsinogen forms trypsin.
b. Two inactive trypsinogen dimers pair to form an active trypsin tetramer.
c. An increase in Ca2+ concentration promotes the conversion.
d. Trypsinogen dimers bind an allosteric modulator, cAMP, causing dissociation into active trypsin monomers.
e. A protein kinase-catalyzed phosphorylation converts trypsinogen to trypsin

Answer 56

a. Proteolysis of trypsinogen forms trypsin.

Question 57

Select the correct statements!

Select one or more:
a. Basic amino acids have a net positive charge at neutral pH.
b. The isoelectric point of basic amino acids is at basic pH.
c. The isoelectric point of the basic amino acids can be calculated as the average of their three pKa values.
d. Arginine is a basic amino acid.

Answer 57

a. Basic amino acids have a net positive charge at neutral pH.
b. The isoelectric point of basic amino acids is at basic pH.
d. Arginine is a basic amino acid.

Question 58

Identify compound A in the reaction catalyzed by glutamate dehydrogenase:

Select one:
a. isocitrate
b. ascorbate
c. alpha-Ketoglutarate
d. oxaloacetate
e. malate

Answer 58

c. alpha-Ketoglutarate

Question 59

Identify compound A in the reaction catalyzed by glutamine synthetase:

Select one:
a. malate
b. L-glutamate
c. alpha-Ketoglutarate
d. oxaloacetate
e. aspartate

Answer 59

b. L-glutamate

Question 60

Identify compound A in the following reaction catalyzed by glutamine synthetase:

Select one:
a. L-asparagine
b. alpha-Ketoglutarate
c. glutathione
d. L-glutamine
e. L-aspartate

Answer 60

d. L-glutamine

Question 61

Identify cofactor A utilized in the reaction catalyzed by glutamine synthetase:

Select one:
a. Mg-GTP
b. Mg-GDP
c. Mg-ATP
d. Mg-ADP
e. Mg-UTP

Answer 61

c. Mg-ATP

Question 62

Identify the cofactor utilized and formed in the reaction catalyzed by glutamine synthetase:

Select one:
a. A is Mg-GTP, B is Mg-ATP
b. A is Mg-ATP, B is Mg- ADP+Pi
c. A is Mg-ADP+Pi, B is Mg- ATP
d. A is Mg-GDP+Pi, B is Mg- GTP
e. A is Mg-GTP, B is Mg- GDP+Pi

Answer 62

b. A is Mg-ATP, B is Mg- ADP+Pi

Question 63

The synthesis of glutamine catalyzed by glutamine synthetase involves the formation of the following intermedier. Name the intermedier:

Select one:
a. aspartyl-phosphate
b. alpha-Ketoglutarate
c. 3-phospho-glycerate
d. 2-phospho-glycerate
e. gamma-glutamyl-phosphate

Answer 63

e. gamma-glutamyl-phosphate

Question 64

Identify compound A in the reaction catalyzed by alanine aminotransferase:

Select one:
a. Lactate
b. Malate
c. Fumarate
d. Pyruvate
e. Succinate

Answer 64

e. Succinate

Question 65

Identify compound A in the following reaction:

Select one:
a. Glycine
b. Ornithine
c. Alanine
d. Glutamine
e. Lactate

Answer 65

c. Alanine

Question 66

Name the enzyme catalysing the following reaction:

Select one:
a. Aspartate dehydrogenase
b. Glutamate dehydrogenase
c. Pyruvate carboxylase
d. Alanine aminotransferase
e. Pyruvate dehydrogenase

Answer 66

d. Alanine aminotransferase

Question 67

Transamination of pyruvate forms the following compound:

Select one:
a. Lactate
b. Aspartate
c. Alanine
d. Malate
e. Glutamate

Answer 67

c. Alanine

Question 68

Transaminases require the following coenzyme:
Select one:

a. Coenzyme A
b. Lipoic acid
c. Biotin
d. Pyridoxal phosphate
e. FAD

Answer 68

d. Pyridoxal phosphate