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BCHS > exam 3 (lec. 13-18) > Flashcards

exam 3 (lec. 13-18) Flashcards

1
Q

Arterial oxygen pressure is ___ torr while in venous blood is ___ torr.

A. 3,10
B. 10, 3
C. 30, 100
D. 100, 30

A

D. 100, 30 (lecture 13)

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2
Q

BPG binds to hemoglobin and ___ oxygen affinity and keeps it in the ___ form.
A. Increases, deoxy
B. Decreases, oxy
C. Increases, oxy
D. Decreases, deoxy

A

D. Decreases, deoxy (lecture 13)

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3
Q

The ___ form of hemoglobin is called the ___ state and results in a blue color of blood.
A. Deoxy, T
B. Oxy, T
C. Deoxy, R
D. Oxy, R

A

A. Deoxy, T (lecture 14)

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4
Q

The oxy form of hemoglobin has:
A. the iron out of the heme plane
B. the iron in the heme plane
C. results in His F8 being 1.6 angstroms from the iron
D. no oxygen bound

A

B. the iron in the heme plane (lecture 14)

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5
Q

Myoglobin:
A. contains a heme with Fe (II) to binds to oxygen
B. contains a heme with Fe (III) to bind to oxygen
C. Transports oxygen throughout the body
D. transports oxygen throughout the body

A

A. contains a heme with Fe (II) to binds to oxygen (lecture 13)

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6
Q

The binding curve of myoglobin is:
A. Hyperbolic with a P50 of 2.8 torr
B. Hyperbolic with a P50 of 28 torr
C. Sigmoidal with a P50 of 2.8 torr
D. Sigmoidal with a P50 of 28 torr

A

A. Hyperbolic with a P50 of 2.8 torr (lecture 13)

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7
Q

The Bohr effect of hemoglobin is:
A. lower pH promotes tighter binding of oxygen by hemoglobin
B. Higher pH promotes easier release of oxygen by hemoglobin
C. Lower pH promotes easier release of oxygen by hemoglobin
D. Higher pH promotes a shift to the right of the oxygen
binding curve

A

Lower pH promotes easier release of oxygen by hemoglobin (lecture 13)

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8
Q

The Hill plot can be used to determine the Hill coefficient of a binding curve. The Hill coefficient is limited by:
A. the number of binding sites for the substrate
B. the cooperativity of the binding sites
C. the negative cooperativity of the binding sites
D. all of the above

A

D. all of the above

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9
Q

Measuring absorbance at ___ nM allows an easy method to determine the amount of oxygen bound to hemoglobin
A. 520
B. 568
C. 578
D. 600

A

C. 578 (lecture 13)

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10
Q

When hemoglobin iron goes from Fe (II) to Fe (III) the color becomes:
A. Red
B. Blue
C. Yellow
D. Brown

A

Brown (lecture 13)

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11
Q

BPG binds to the:
A. Deoxy state of hemoglobin’s alpha subunit
B. Oxy state of hemoglobin’s beta subunit
C. Oxy state of hemoglobin’s gamma subunit
D. Deoxy state of hemoglobin’s beta subunit

A

D. Deoxy state of hemoglobin’s beta subunit

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12
Q

The Boston mutant of hemoglobin (His58Tyr):
A. weakens heme binding
B. disrupts the H helix
C. promotes methemoglobin formation
D. disrupts the hydrogen bond that stabilizes the R conformation

A

C. Promotes methemoglobin formation

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13
Q

Fetal hemoglobin:
A. lacks an alpha subunit
B. contains BPG binding sites
C. lacks BPG binding sites
D. contains beta subunits

A

C. Lacks BPG binding sites

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14
Q

Myosin filament heads:
A. attach to actin
B. walk along kinesin
C. bind ATP to release microtubules
D. bind ADP to start the whole cycle of myosin muscle contraction

A

A. Attach to actin (lecture 14)

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15
Q

Enzymes are necessary for:
A. Milder reaction conditions
B. Reaction specificity
C. Reaction regulation
D. All of the above

A

D. All of the above (lecture 15)

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16
Q

Enzymes:
A. reduce the delta G of the reaction
B. Reduce the delta G
C. Needs ions to function
D. remove the need for intermediates

A

B. reduce the delta G

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17
Q

Which can enzymes not do without cofactors:
A. carry out acid-base reactions
B. transient covalent bonds
C. oxidation-reduction reactions
D. charge-charge reactions

A

C. oxidation-reduction reactions (lecture 15)

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18
Q

Which type of interaction does not help with enzyme substrate specificity?
A. Hydrogen bonding
B. Hydrophobic interactions
C. Ionic interactions
D. Covalent interactions

A

D. Covalent interactions (lecture 16)

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19
Q

Which is not a class of enzyme according to the reaction type:
A. Ion channels
B. Isomerases
C. Lyases
D. Ligases

A

A. Ion channels (DUHH)

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20
Q

The lack of nicotinamide in the diet results in:
A. Beriberi
B. Pellagra
C. Pernicious Anemia
D. Scurvy

A

B. Pellagra (lecture 15)

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21
Q

Given a bisubstrate reaction, when either substrate can bind first, it is called a:
a. ordered mechanism
b. ping pong mechanism
c. primary mechanism
d. random mechanism

A

d. random mechanism

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22
Q

Which amino acid could help with acid-base catalysis:
A. Ala
B. Asp
C. Phe
D. Thr

A

B. Asp
(Asp, Glu, His, Tyr, Cys, Lys)

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23
Q

Covalent catalysis usually requires a:
A. Metal Ion
B. Asp residue
C. Nucleophile
D. None of the above

A

C. Nucleophile (lecture 16)

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24
Q

Which amino acid cannot act as a nucleophile:
A. Cys
B. His
C. Ile
D. Thr

A

C. Ile

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25
Q

Chymotrypsin and ___ are an example of divergent evolution:
A. Elastase
B. Serine carboxy peptidase
C. Subtilisin
D. None of the above

A

A. Elactase (lecture 17)

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26
Q

Lysozyme uses ___ as the first step of its catalysis
A. general acid catalysis
B. Transition state catalysis
C. General base catalysis
D. Nucleophilic attack catalysis

A

A. general acid catalysis (lecture 17)

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27
Q

The specificity pocket of a serine protease which preferentially binds Asp could have in it:
a. S189 G216 G286
b. D189 G216 G286
c. L189 T216 V286
d. K189 G216 G286

A

d. K189 G216 G286 (lecture 17)

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28
Q

The catalytic triad of serine proteases is made up of:
a. His Gly Ser
b. Asp His Ser
c. Asp Glu Ser
d. Different from above

A

b. Asp His Ser (lecture 17)

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29
Q

The delta G reaction is the difference in the:
a. Delta G of products and reactants
b. Delta G of activation energy with and without enzyme
c. Delta G of reactants and activation energy with
enzyme
d. Delta G of products and the activation energy without
enzyme

A

a. Delta G of products and reactants

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30
Q

The delta delta G‡cat of the reaction of products with a
delta G of 20 kj/mol, reactants with a delta G of 15 kj/mol
a. 5 kJ/mol
b. 10 kJ/mol
c. 15 kJ/mol
d. 20 kJ/mol

A

b. 10 kJ/mol

31
Q

Enzyme kinetics is important because:
a. It allows the mechanism of a reaction to be determined
with structural and chemical data
b. It allows understanding of the enzyme’s role in metabolic pathways
c. Substrate binding constants can be measured
d. All of the above

A

d. All of the above (lecture 18)

32
Q

The rate of a second order reaction such as 2[A] -> P can
be determined by:
a. Plotting ln [A] versus time and determining the y-intercept
b. Plotting ln [A] versus time and determining the
negative slope of the line
c. Plotting 1/[A] versus time and determining the slope of the line
d. Plotting 1/[A] versus time and determining the y-intercept

A

c. Plotting 1/[A] versus time and determining the slope of the line

33
Q

The greater the delta G‡:
a. The more stable the transition state and the slower the reaction
b. The more unstable the transition state and the SLOWER the reaction
c. It says nothing about the reaction rate
d. The reaction rate does not depend on the delta G‡

A

b. The more unstable the transition state and the SLOWER the reaction (lecture 18)

34
Q

. A delta delta G‡ cat of 22.8 kJ/mol produces an increase of reaction rate of approximately:
a. 100 times
b. 1000 times
c. 10000 times
d. 100000 times

A

c. 10000 times

35
Q

What can be said about the enzymatic rate when substrate
concentration is equivalent to Km?
a. Vmax occurs
b. Vmax/2 occurs
c. Initial rate occurs
d. Cannot tell anything about reaction rate.

A

b. Vmax/2 occurs

36
Q

The slope of the Lineweaver-Burke graph gives:
a. 1/Vmax
b. 1/Km
c. Km/Vmax
d. Vmax/Km

A

c. Km/Vmax

37
Q

The following Lineweaver-Burke graph is representative
of what kind of inhibition:
(graph shows no intersection between red and blue line)
a. Competitive
b. Mixed
c. Noncompetitive
d. Uncompetitive

A

d. uncompetitive

if graph shows intersection at y-axis –> competitve

if graph shows intersection starting at negative x-axis –> noncompetitive

38
Q

Calculate the p50 value for Protein Y, that has a
cooperativity of 2, if YO2=0.34 when pO2= 18 torr
a. 20 torr
b. 25 torr
c. 30 torr
d. 35 torr

A

b. 25 torr

39
Q

In a rapidly respiring muscle cell, myoglobin:
a. Increases the rate O2 can diffuse through the cell
b. Decreases the solubility of O2
c. Increases the binding capacity of hemoglobin
d. None of the above

A

a. Increases the rate O2 can diffuse through the cell (lecture 13)

40
Q

Carbamate forms as a product of what reaction?
a. CO2 and the amino groups in oxyhemoglobin
b. O2 and the amino groups in deoxyhemoglobin
c. CO2 and the amino groups in deoxyhemoglobin
d. O2 and the amino groups in oxyhemoglobin

A

c. CO2 and the amino groups in deoxyhemoglobin (lecture 13)

41
Q

Calcium regulates muscle contraction by:
a. Binding to tropomyosin to expose the troponin binding
site
b. Binding troponin to expose the myosin binding site
c. Binding to actin to expose the troponin binding site
d. Binding to myosin to expose the actin binding site

A

b. Binding troponin to expose the myosin binding site (lecture 14)

42
Q

How is ATP hydrolysis involved in muscle contraction?
a. Directly precedes the power stroke step
b. Causes myosin to release actin
c. Causes the heavy chain of actin to release myosin
d. Causes “cocking” of the myosin head

A

d. Causes “cocking” of the myosin head (number 2 of the step)

43
Q

Which of the following statements regarding muscle
contraction is correct?
a. Myosin functions through a power stroke mechanism
b. Actin functions through a power stroke mechanism
c. Both A and B
d. Neither A or B

A

a. Myosin functions through a power stroke mechanism (lecture 14)

44
Q

In a multistep reaction, the rate determining step
corresponds to
a. The step with the highest free energy (delta G)
b. The step with the lowest free energy (delta G)
c. The step with the lowest free energy of activation
(delta G‡)
d. The step with the highest free energy of activation
(delta G‡)

A

d. The step with the highest free energy of activation (delta G‡)

45
Q

Which RNA residue is important for the function of the
enzyme RNAse, and results in the specificity
a. The 3’-OH
b. The 2’-OH
c. The 2’-H
d. The 3’-H

A

b. The 2’-OH

46
Q

Metal ions are effective catalysts because:
a. They can have charges greater than one
b. They can be present at higher concentrations,
compared to protons, at neutral pH
c. They cannot ionize water, unlike protons
d. Two of the above

A

d. Two of the above (lecture 16)

47
Q

The reaction 2A-> B+C has a rate constant of 10-4M-1 s1 and a reaction velocity of 9.61 x 10-2 Ms-1. What is the
concentration
a. 20 M
b. 40 M
c. 0.03 M
d. 31 M

A

d. 31M

48
Q

The hypothetical compound X irreversibly binds to an
enzyme, but does not affect the unbound enzyme. How does compound X affect the apparent
a. Apparent Km decreases and apparent Vmax increases
b. Both apparent Km and apparent Vmax decrease
c. Apparent Km stays the same and apparent Vmax decreases
d. Both apparent Km and apparent Vmax increase

A

c. Apparent Km stays the same and apparent Vmax decreases (lecture 18)

49
Q

You are running a kinetics experiment and all of your enzyme is currently bound to substrate. What is the effect of
a. The rate increases
b. The rate stays the same
c. The rate decreases
d. Because all substrate is bound, only the Km is affected

A

b. The rate stays the same

50
Q

Asparagine is formed through the following reaction:
aspartate + ATP + HN3 = asparagine +AMP+PPI. What type of enzyme catalyzes the reaction?
a. Oxidoreductase
b. Ligase
c. Hydrolase
d. Lyase

A

b. Ligase

51
Q

The following figure is the structure of :
(OH all on one side)
a. D-Arabinose
b. D-Lyxose
c. D-Ribose
d. D-Xylose

A

d. D-ribose……. i think

52
Q

Hypothetical enzyme A function optimally at pH of -5. How would the enzyme be affected if moved to a solution of physiological pH?
a. the inside would not be affected
b. the enzyme would be less catalytically active
c. the enzyme would be more catalytically active
d. there is no way to know

A

b. the enzyme would be less catalytically active

53
Q

Which of the following is true regarding reactions?
a. the free energy of an intermediate can be greater than the reactant
b. the absolute value of delta G for a reaction can be larger than delta G cross
c. delta G cross for an enzyme-catalyzed reaction can be greater than delta G cross for nonenzymatic reaction
d. only A and B

A

d. only A and B

54
Q

Given the following reaction scheme, what type of catalysis does step 2 represent:
a. acid base catalysis
b. covalent bond catalysis
c. ion metal catalysis
d. transition state catalysis

A

a. acid base catalysis

55
Q

Which of the following amino acids has the most significant role in the molecular mechanisms of hemglobin’s function?

A

Histidine

56
Q

At what oxygen concentration will myoglobin be 85% saturated with oxygen? (p50=2.8 torr)

A

15.9

57
Q

If curve 3 represents the binding of oxygen to Hb in normal red blood cells, which of the curves would represent the binding of oxygen to Hb in red blood cells that contain NO BPG?

A

2

58
Q

How does sliding filament model explain the shortening of the sarcomere during muscle contraction?

A

shortening of I band bc of INCREASED thin and thick filament overlap (lecture 14)

59
Q

If you add enzyme to a solution containing only the product(s) of a reaction, would you expect any substrate to form?

A

No, irreversible

60
Q

Which one of the following is correct
I. All enzymes are highly specific for the reactions they catalyze
II. Prosthetic groups are loosely associated with the polypeptide chain of an enzyme.
III. If an enzyme-catalyzed reaction requires a group with a low pK to be deprotonated and a group with a higher pK to be protonated, the pH vs. rate curve will have a peak in the middle of the two pK values.
IV. When comparing types of catalysis the proximity effect provides the largest rate enhancement

A

I, III

61
Q

Which one of the following statements about enzyme catalyzed reactions is FALSE?

A

changes delta G reaction

62
Q

A new drug has been discovered which inhibits the reaction catalyzed by enzyme A. Based on the information shown below, what is the drug?
(graph shows red and blue lines intersecting at y-axis)

A

competitive inhibitor

63
Q

Which of the following is TRUE in competitive inhibition?

A

it reversibly binds?

64
Q

. A delta delta G‡ cat of 28.75 kj/mol produces an increase of reaction rate of approximately:
a. 100 times
b. 1000 times
c. 10000 times
d. 100000 times

A

d. 100,000 times

65
Q

What is the sugar used in DNA or RNA?

A

ribose deoxyribose

66
Q

What kind of bond is between 2 sugars?

A

glycosidic bonds

67
Q

Which glucose containing structure is in sheets?

A

cellulose

68
Q

Name a function of sugars on proteins:

A
  • protect protein structure
  • define protein structure
  • self signaling/recognition between sugars
69
Q

Breaking down complex metabolites to simple products leads to what?

A

release of energy

70
Q

What are the three main pathways that lead to energy production?

A
  • Glycolysis
  • Citric acid cycle
  • Oxidative-Phosphorylation
71
Q

Why separate pathways?

A
72
Q

Why understand organic model reactions?

A

to understand

73
Q
A

BCHS (7 decks)

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