Test Bank Essential Organic Chemistry 2nd Edition By Bruice

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Test Bank Essential Organic Chemistry 2nd Edition By Bruice

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WITH ANSWERS

 

Test Bank Essential Organic Chemistry 2nd Edition By Bruice

 

Essential Organic Chemistry, 2e (Bruice)


Chapter 4


Alkenes: Structure, Nomenclature, Stability, and an Introduction
to Reactivity


1)
 

What is the molecular formula of the hydrocarbon that contains 5 carbon atoms, one ring, and one   bond?

 

Answer:
 

C5H8

 

Section:


4.1


2)
 

What is the molecular formula of the hydrocarbon that contains 8 carbon atoms, one ring, and two   bonds?

 

Answer:
 

C8H12

 

Section:


4.1


3)
 

What is the condensed formula of an unsaturated hydrocarbon containing three carbons?

 

Answer:
 

CH2=CHCH3

 

Section:


4.1


4)
 

What is the name given to a compound containing only carbons and hydrogens and having the maximiun number of hydrogens in the molecule?

 

  1. A)

 

alkene

 

  1. B)

 

nonsaturated hydrocarbon

 

  1. C)

 

unsaturated hydrocarbon

 

  1. D)

 

saturated hydrocarbon

 

  1. E)

 

alkyne

 

Answer:
 

D

 

Section:


4.1


5)
 

What is the common name for the following compound?

 

 

 

  1. A)

 

t-Butylene

 

  1. B)

 

sec-Butylene

 

  1. C)

 

Isobutylene

 

  1. D)

 

Butylene

 

  1. E)

 

Methylpropylene

 

Answer:
 

C

 

Section:


4.2


6)
 

What is the IUPAC name for the following compound?

 

 

 

  1. A)

 

2-methyl-1-butene

 

  1. B)

 

Isopentene

 

  1. C)

 

2-methylbutene

 

  1. D)

 

2-Ethylpropene

 

  1. E)

 

3-methyl-3-butene

 

Answer:
 

A

 

Section:


4.2


7)
 

What is the IUPAC name for the following compound?

 

 

 

  1. A)

 

5-methylcyclohexene

 

  1. B)

 

4-methylcyclohexene

 

  1. C)

 

1-methyl-3-cyclohexene

 

  1. D)

 

1-methyl-4-cyclohexene

 

  1. E)

 

methylcyclohexene

 

Answer:
 

B

 

Section:


4.2


8)
 

Which of the following is vinyl chloride?

 

  1. A)

 

CH3CH2Cl

 

  1. B)

 

CH2CHCH2Cl

 

  1. C)

 

CH2CHCl

 

  1. D)

 

 

 

 

  1. E)

 

 

 

 

Answer:
 

C

 

Section:


4.2


9)
 

Provide the proper IUPAC name for the alkene shown below.

 

 

 

Answer:
 

6-bromo-1-methylcyclohexene

 

Section:


4.2


10)
 

Provide the systematic name of the alkene below.

 

 

 

Answer:
 

2-ethyl-1-hexene

 

Section:


4.2


11)
 

Which of the following is an allylic alcohol?

 

  1. A)

 

CH2=CHCH2OCH3

 

  1. B)

 

CH2=CHCH2CH3

 

  1. C)

 

HOCH=CHCH2CH3

 

  1. D)

 

CH3CH=CHCH2OH

 

  1. E)

 

CH2=CHCH2CH2OH

 

Answer:
 

D

 

Section:


4.2


12)
 

Provide the systematic name of the compound below.

 

 

Answer:
 

5-isobutyl-1-methylcyclopentene

 

Section:


4.2


13)
 

Which of the following statements about ethene, C2H4, is incorrect?

 

  1. A)

 

The H-C-H bond angles are approximately 109.5.

 

  1. B)

 

All of the hydrogen atoms are in the same plane.

 

  1. C)

 

There is a total of five sigma bonds.

 

  1. D)

 

The carbon atoms are sp2 hybridized.

 

  1. E)

 

The H-C-H bond angles are approximately 120.

 

Answer:
 

A

 

Section:


4.3


14)
 

What is the hybridization of the carbon atom marked with an arrow in the molecule?

 

 

 

  1. A)

 

2sp3

 

  1. B)

 

sp

 

  1. C)

 

sp2

 

  1. D)

 

d2sp3

 

  1. E)

 

sp3

 

Answer:
 

C

 

Section:


4.3


15)
 

What is the hybridization of the carbon marked with an arrow in the molecule?

 

 

 

  1. A)

 

sp

 

  1. B)

 

sp2

 

  1. C)

 

sp3

 

  1. D)

 

4sp3

 

  1. E)

 

sp2f

 

Answer:
 

B

 

Section:


4.3


16)
 

Which of the following statements about propene, CH3CHCH2, is correct?

 

  1. A)

 

All nine atoms lie in the same plane.

 

  1. B)

 

The compound has a cis and trans isomer.

 

  1. C)

 

It generally acts as a Lewis acid.

 

  1. D)

 

There is a total of eight sigma bonds.

 

  1. E)

 

All the carbon atoms are sp2 hybridized.

 

Answer:
 

D

 

Section:


4.3


17)
 

Which of the following is capable of exhibiting cis-trans isomerism?

 

  1. A)

 

1-butene

 

  1. B)

 

1-pentene

 

  1. C)

 

cyclohexene

 

  1. D)

 

ethene

 

  1. E)

 

2-butene

 

Answer:
 

E

 

Section:


4.4


18)
 

Draw all the possible constitutional isomers of C4H8.

 

Answer:
 

 

 

 

Section:


4.4


19)
 

What is the IUPAC name of the structure shown below?

 

 

 

  1. A)

 

cis-4-methyl-2-pentene

 

  1. B)

 

cis-2-methyl-3-pentene

 

  1. C)

 

trans-2-methyl-3-pentene

 

  1. D)

 

(E)-2-methyl-3-pentene

 

  1. E)

 

trans-4-methyl-2-pentene

 

Answer:
 

E

 

Section:


4.4


20)
 

What is the IUPAC name of the structure shown below?

 

 

 

  1. A)

 

1-chloro-2-pentene

 

  1. B)

 

trans-4-chloro-3-butene

 

  1. C)

 

cis-1-chloro-1-butene

 

  1. D)

 

(Z)-1-chloro-2-butene

 

  1. E)

 

trans-1-chloro-1-propene

 

Answer:
 

C

 

Section:


4.4


21)
 

Assign the E or Z configuration to the following molecule:

 

 

 

Answer:
 

The molecule has a Z configuration based on the priority rule established by Cahn-Ingold-Prelog.

 

 

 

Section:


4.5


22)
 

Provide the proper IUPAC name for the alkene shown below.

 

 

 

Answer:
 

(E)-3,4-dimethyl-3-heptene

 

Section:


4.5


23)
 

Which of the following best describes the geometry about the carbon-carbon double bond in the alkene below?

 

 

 

  1. A)

 

E

 

  1. B)

 

Z

 

  1. C)

 

neither E nor Z

 

  1. D)

 

cis


  1. E)

 

trans


Answer:
 

C

 

Section:


4.5


24)
 

Draw the structure of (Z)-4-ethyl-3-methyl-3-heptene.

 

Answer:
 

 

 

 

Section:


4.5


25)
 

Draw and name the six alkenes which have the molecular formula C5H10.

 

Answer:
 

 

 

 

Section:


4.4 and 4.5


26)
 

Which of the following is the most stable alkene?

 

  1. A)

 

 

 

 

  1. B)

 

 

 

 

  1. C)

 

 

 

 

  1. D)

 

 

 

 

  1. E)

 

 

 

 

Answer:
 

E

 

Section:


4.6


27)
 

Which of the following is the most stable alkene?

 

  1. A)

 

trans-3-hexene

 

  1. B)

 

cis-3-hexene

 

  1. C)

 

1-hexene

 

  1. D)

 

cis-2,2,5,5-tetramethyl-3-hexene

 

  1. E)

 

(Z)-3-hexene

 

Answer:
 

A

 

Section:


4.6


28)
 

Which of the following is not an electrophile?

 

  1. A)

 

H+

 

  1. B)

 

+NH4

 

  1. C)

 

+NO2

 

  1. D)

 

Fe+3

 

  1. E)

 

CH2CH2

 

Answer:
 

E

 

Section:


4.7


29)
 

Which of the following statements is incorrect?

 

  1. A)

 

Electrons movetoward positively charged locations.

 

  1. B)

 

An electron-rich atom is called an electrophile.

 

  1. C)

 

An electrophile is electon loving.

 

  1. D)

 

Electron-rich atoms are attracted to electron-deficient atoms.

 

  1. E)

 

a nucleophile has a a pair of electrons it can share.

 

Answer:
 

B

 

Section:


4.7


30)
 

Which of the following is not a nucleophile?

 

  1. A)

 

FeBr3

 

  1. B)

 

Br-

 

  1. C)

 

NH3

 

  1. D)

 

 

 

  1. E)

 

CH3OCH3

 

Answer:
 

A

 

Section:


4.7


31)
 

What does a curved arrow represent?

 

  1. A)

 

that two structures are resonance structures

 

  1. B)

 

the movement of two electrons

 

  1. C)

 

a link between reactants and products

 

  1. D)

 

that two structures are equivalent

 

Answer:
 

B

 

Section:


4.7


32)
 

Draw the curved arrows to show how CH3CH=CHCH3 reacts with HBr to form a

carbocation.

 

Answer:
 

 

 

 

Section:


4.7


33)
 

A nucleophile acts as a __________ when it reacts with an electrophile.

 

  1. A)

 

Bronsted-Lowry acid

 

  1. B)

 

Arrhenius base

 

  1. C)

 

Lewis acid

 

  1. D)

 

Lewis base

 

  1. E)

 

none of the above

 

Answer:
 

D

 

Section:


4.7


34)
 

An electrophile acts as a __________ when it reacts with a nucleophile.

 

  1. A)

 

Bronsted-Lowry base

 

  1. B)

 

Arrhenius base

 

  1. C)

 

Lewis acid

 

  1. D)

 

Lewis base

 

  1. E)

 

none of the above

 

Answer:
 

C

 

Section:


4.7


35)
 

Which of the following is correct?

 

  1. A)

 

Curved arrows are always drawn from an electron poor center to an electron rich center.

 

  1. B)

 

A doubled headed arrow means one electron has been moved.

 

  1. C)

 

Curved arrows are always drawn from an electron rich center to an electron poor center.

 

  1. D)

 

A single headed arrow means two electrons have been moved.

 

  1. E)

 

Curved arrows are used to show movement of protons.

 

Answer:
 

C

 

Section:


4.7


36)
 

How many transition states are present in the following reaction diagram?

 

 

 

  1. A)

 

3

 

  1. B)

 

4

 

  1. C)

 

5

 

  1. D)

 

2

 

  1. E)

 

1

 

Answer:
 

D

 

Section:


4.8


37)
 

What is used to represent a transition state structure?

 

  1. A)

 

The structure is inside parentheses which have a double dagger superscript.

 

  1. B)

 

The structure is inside brackets which have a single dagger superscript.

 

  1. C)

 

The structure is inside brackets which have a double dagger superscript.

 

  1. D)

 

The structure is inside brackets which have a triple dagger superscript.

 

  1. E)

 

The structure is inside parentheses which have a single dagger superscript.

 

Answer:
 

C

 

Section:


4.8


38)
 

An increase in which of the following results in a decrease in the rate of the chemical reaction?

 

  1. A)

 

temperature

 

  1. B)

 

concentration

 

  1. C)

 

collision frequency

 

  1. D)

 

energy of activation

 

  1. E)

 

fraction of collisions with proper orientation

 

Answer:
 

D

 

Section:


4.8


39)
 

An increase in which of the following will occur if the reaction temperature is increased?

 

  1. Energy of activation
  2. Collision frequency

III.     Fraction of collisions with sufficient energy

 

  1. A)

 

I and II

 

  1. B)

 

I and III

 

  1. C)

 

II and III

 

  1. D)

 

I, II, and III

 

  1. E)

 

I

 

Answer:
 

C

 

Section:


4.8


40)
 

What is the activation energy for the reaction B A in the following diagram?

 

 

 

  1. A)

 

A

 

  1. B)

 

B

 

  1. C)

 

C

 

  1. D)

 

D

 

  1. E)

 

E

 

Answer:
 

E

 

Section:


4.8


41)
 

Which of the following correctly describes intermediates and/or transition states?

 

  1. A)

 

Transition states occur at minima on reaction coordinate diagrams.

 

  1. B)

 

Both transition states and intermediates occur at maxima on reaction coordinate diagrams.

 

  1. C)

 

An intermediate is always produced after the rate-determining step of a reaction mechanism.

 

  1. D)

 

Transition states have partially formed bonds whereas intermediates have fully formed bonds.

 

  1. E)

 

none of the above

 

Answer:
 

D

 

Section:


4.8


42)
 

Based on the following energy diagram, what is B?

 

 

 

  1. A)

 

activation energy

 

  1. B)

 

activated complex

 

  1. C)

 

transition state

 

  1. D)

 

intermediate

 

  1. E)

 

none of the above

 

Answer:
 

D

 

Section:


4.8


43)
 

The reaction step that has its transition state at the highest point on the reaction coordinate is the called the __________.

 

  1. A)

 

rate-determining step

 

  1. B)

 

activation energy

 

  1. C)

 

transition step

 

  1. D)

 

product favored step

 

  1. E)

 

reactant favored step

 

Answer:
 

A

 

Section:


4.8


 

 

Essential Organic Chemistry, 2e (Bruice)


Chapter 17


How Enzymes Catalyze Reactions : The Organic Chemistry
of the Vitamins


1)
 

Most biological catalyst are enzymes.

 

Answer:
 

TRUE

 

Section:


17.0


2)
 

What is the name for the reactant in an enzyme-catalyzed reaction?

 

  1. A)

 

solvent

 

  1. B)

 

active site

 

  1. C)

 

cofactor

 

  1. D)

 

substrate

 

  1. E)

 

coenzyme catalysis

 

Answer:
 

D

 

Section:


17.1


3)
 

How do enzymes differ from nonbiological catalysts?

 

  1. A)

 

They have specificity for the substrate.

 

  1. B)

 

They have lower molecular weights than nonbiological catalysts.

 

  1. C)

 

They require higher pressure to be functional.

 

  1. D)

 

They require lower pH to be functional.

 

  1. E)

 

They are more polar than nonbiological catalysts.

 

Answer:
 

A

 

Section:


17.1


4)
 

Which of the following statements account for the remarkable catalytic ability of enzymes?

 

  1. A)

 

proper positioning and specificity of active site and substrate

 

  1. B)

 

proper positioning of amino acid side chains that serve as catalytic groups

 

  1. C)

 

ability of the groups on the enzyme to stabilize transition states

 

  1. D)

 

A and B

 

  1. E)

 

all of the above

 

Answer:
 

A

 

Section:


17.1


5)
 

Explain the phenomenon known as molecular recognition. Give an example.

 

Answer:
 

Molecular recognition is the ability of one molecule to selectively bind or coordinate to another molecule, especially in a complex environment.

Ex.

The specificity of the active site of the enzyme for its substrate. This results from the conformation of the protein and the particular amino acid side chains that make up the active site. There are many other kinds of molecular recognition other than enzyme-substrate; hormone-receptors and inhibitor-enzyme.

 

Section:


17.1


6)
 

What suffix is used for most enzymes?

 

  1. A)

 

yme

 

  1. B)

 

mes

 

  1. C)

 

ose

 

  1. D)

 

ese

 

  1. E)

 

ase

 

Answer:
 

E

 

Section:


17.2


7)
 

Which of the following is considered an acid catalyst?

 

  1. A)

 

histidine side chain

 

  1. B)

 

protonated lysine side chain

 

  1. C)

 

glutamate residue

 

  1. D)

 

B only

 

  1. E)

 

A and C

 

Answer:
 

D

 

Section:


17.2


8)
 

Which of the following is considered a base catalyst?

 

  1. A)

 

histidine side chain

 

  1. B)

 

protonated lysine side chain

 

  1. C)

 

glutamate residue

 

  1. D)

 

B only

 

  1. E)

 

A and C

 

Answer:
 

E

 

Section:


17.2


9)
 

What is D-fructose-1,6-diphosphate converted into by aldolase?

 

  1. A)

 

fructose

 

  1. B)

 

D-glyceraldehyde-3-phosphate

 

  1. C)

 

dihydroxyacetone phosphate

 

  1. D)

 

A and B

 

  1. E)

 

B and C

 

Answer:
 

E

 

Section:


17.3


10)
 

Which of the following is not true about the enzyme aldolase?

 

  1. A)

 

It catalyzes the cleavage of D-glucose into two molecules each containing 3-carbons.

 

  1. B)

 

It catalyzes the cleavage of D-galactose into two molecules each containing 3-carbons.

 

  1. C)

 

It catalyzes the cleavage of a six carbon compound into two three carbon compounds.

 

  1. D)

 

It catalyzes the cleavage of D-fructose 1,6-diphosphate into glyceraldehyde-3-phosphate and dihydroxyacetone phosphate.

 

  1. E)

 

The enzyme is called aldolase because the reverse reaction is an aldol condensation.

 

Answer:
 

B

 

Section:


17.3


11)
 

Which of the following residues acts as a general-base catalyst in the cleavage of the C3-C4 bond in the mechanism of the aldolase-catalyzed reaction?

 

  1. A)

 

Methionine

 

  1. B)

 

Histidine

 

  1. C)

 

Cysteine

 

  1. D)

 

Asparagine

 

  1. E)

 

Lysine

 

Answer:
 

C

 

Section:


17.3


12)
 

Which of the following residues acts as a general-acid catalyst in aldolase but as a general-base catalyst in chymotrypsin?

 

  1. A)

 

Methionine

 

  1. B)

 

Histidine

 

  1. C)

 

Cysteine

 

  1. D)

 

Asparagine

 

  1. E)

 

Lysine

 

Answer:
 

B

 

Section:


17.3


13)
 

In which of the following classes of reactions is a coenzyme required?

 

  1. A)

 

oxidation reactions

 

  1. B)

 

two carbon transfer

 

  1. C)

 

acyl transfer

 

  1. D)

 

reduction reactions

 

  1. E)

 

A, B, and D

 

Answer:
 

E

 

Section:


17.4


14)
 

Which of the following statements best describes what cofactors are?

 

  1. A)

 

They are metal ions that assist enzymes in carrying out their catalytic reactions.

 

  1. B)

 

They are organic molecules that assist enzymes in carrying out their catalytic reactions.

 

  1. C)

 

They are organic molecules called coenzymes.

 

  1. D)

 

They are organic molecules derived from compounds commonly known as vitamins.

 

  1. E)

 

all of the above

 

Answer:
 

E

 

Section:


17.4


15)
 

Which of the following statements is not true of coenzymes?

 

  1. A)

 

Coenzymes catalyze chemical reactions similar to enzymes.

 

  1. B)

 

Coenzymes may function as oxidizing and reducing agents.

 

  1. C)

 

Coenzymes play a variety of chemical roles exactly like those played by the amino acid side chains of enzymes.

 

  1. D)

 

Coenzymes may function as nucleophiles or strong bases needed in a reaction.

 

  1. E)

 

Coenzymes may function as activators needed in a reaction.

 

Answer:
 

C

 

Section:


17.4


16)
 

Which of the following is not a lipid-soluble vitamin?

 

  1. A)

 

vitamin A

 

  1. B)

 

vitamin D

 

  1. C)

 

vitamin E

 

  1. D)

 

vitamin C

 

  1. E)

 

vitamin K

 

Answer:
 

D

 

Section:


17.4


17)
 

Which of the following vitamins is the only water-soluble vitamin that does not function as a coenzyme?

 

  1. A)

 

vitamin B12

 

  1. B)

 

riboflavin (B2)

 

  1. C)

 

vitamin C

 

  1. D)

 

thiamine (B1)

 

  1. E)

 

pyridoxine (B6)

 

Answer:
 

C

 

Section:


17.4


18)
 

Which of the following vitamins can be synthesized by all mammals except humans and guinea pigs?

 

  1. A)

 

vitamin B12

 

  1. B)

 

riboflavin (B2)

 

  1. C)

 

vitamin C

 

  1. D)

 

thiamine (B1)

 

  1. E)

 

pyridoxine (B6)

 

Answer:
 

C

 

Section:


17.4


19)
 

Which type of vitamins, water-soluble or lipid-soluble, can we overdose on?

 

Answer:
 

One can overdose on lipid-soluble vitamins because they are not easily eliminated by the body and can accumulate in cell membranes and other nonpolar components of the body.

 

Section:


17.4


20)
 

Which of the following vitamins are radical inhibitors or antioxidants?

 

  1. A)

 

niacin

 

  1. B)

 

vitamins B1 and B12

 

  1. C)

 

vitamins B2 and B6

 

  1. D)

 

vitamins A and D

 

  1. E)

 

vitamins C and E

 

Answer:
 

E

 

Section:


17.4


21)
 

Which coenzyme is used by enzymes to catalyze oxidation reactions?

 

  1. A)

 

NADH

 

  1. B)

 

NAD+

 

  1. C)

 

FAD

 

  1. D)

 

THF

 

  1. E)

 

B and C

 

Answer:
 

E

 

Section:


17.5


22)
 

In a process known as oxidative phosphorylation, every NADH that is formed in carrying out oxidation reactions in the early stages of catabolism is converted into __________.

 

  1. A)

 

three ATPs

 

  1. B)

 

two ATPs

 

  1. C)

 

four FADHs

 

  1. D)

 

six acetyl-CoAs

 

  1. E)

 

none of the above

 

Answer:
 

A

 

Section:


17.5


23)
 

Which of the following is/are coenzyme(s) formed from the vitamin niacin?

 

  1. A)

 

NAD+

 

  1. B)

 

NADP+

 

  1. C)

 

NADH

 

  1. D)

 

NADPH

 

  1. E)

 

all of the above

 

Answer:
 

E

 

Section:


17.5


24)
 

At what position of the pyridine ring in the following coenzyme will oxidation-reduction reactions take place?

 

 

 

  1. A)

 

1

 

  1. B)

 

2

 

  1. C)

 

3

 

  1. D)

 

4

 

  1. E)

 

5

 

Answer:
 

D

 

Section:


17.5


25)
 

What is the major organic product of this oxidation-reduction reaction?

 

 

 

  1. A)

 

 

 

 

  1. B)

 

 

 

 

  1. C)

 

 

 

 

  1. D)

 

 

 

 

  1. E)

 

 

 

 

Answer:
 

E

 

Section:


17.5


26)
 

Generally speaking, which of the following oxidation-reduction reactions utilize NAD+ and NADP+ as oxidation coenzymes?

 

  1. A)

 

alcohols oxidized to ketones

 

  1. B)

 

alcohols oxidized to aldehydes

 

  1. C)

 

alcohols oxidized to carboxylic acids

 

  1. D)

 

A and B

 

  1. E)

 

A, B, and C

 

Answer:
 

E

 

Section:


17.5


27)
 

Explain what is meant by a nucleotide and give an example.

 

Answer:
 

A nucleotide is composed of a heterocyclic molecule attached to the -position of a phosphorylated ribose.

Ex.

NAD+ (nicotinamide adenine dinucleotide) is composed of two nucleotides linked together through their phosphate group.

 

Section:


17.5


28)
 

Can an NAD+/NADH dependent enzyme tell the difference between the pro-R hydrogen and pro-S hydrogen of a substrate? Explain.

 

Answer:
 

The enzyme can tell the difference between R and S hydrogens because the enzyme has a specific binding site for its coenzyme which blocks one of the coenzymes sides, leaving the other side open for the substrate to bind to. For example, alcohol dehydrogenase removes only the pro-R hydrogen of ethanol.

 

Section:


17.5


29)
 

Which of the following statements regarding glycolysis is correct?

 

  1. A)

 

Glycolysis is another name for the Krebs cycle.

 

  1. B)

 

Disaccharides can enter glycolysis without being hydrolyzed.

 

  1. C)

 

Glycolysis occurs primarily in the fluid outside the cell.

 

  1. D)

 

Glycolysis is the series of reactions which produces 2 moles of pyruvate from each mole of D-glucose.

 

  1. E)

 

Glycolysis is the series of reactions which is responsible for the complete oxidation of pyruvate and acetyl-CoA to carbon dioxide.

 

Answer:
 

D

 

Section:


17.5


30)
 

What structural feature of enzymes that catalyze redox reactions requires the presence of a coenzyme for reaction to occur?

 

Answer:
 

An enzyme that catalyzes a redox reaction requires a coenzyme because none of the amino acid side chains can act as oxidizing or reducing agents.

 

Section:


17.5


31)
 

What are the main structural and functional differences between NAD+/NADH and NADP+/NADPH?

 

Answer:
 

The only way in which NADP+ differs structurally from NAD+ is the phosphate group bonded to the 2-OH group of the ribose of the adenine nucleotide. Functionally, NAD+ and NADH are generally used as coenzymes in catabolic reactions while NADP+ and NADPH are generally used as coenzymes in anabolic reactions.

 

Section:


17.5


32)
 

Explain why a cell typically maintains its [NAD+]/[NADH] ratio near 1000 while maintaining its [NADP+]/[NADPH] ratio at about 0.01.

 

Answer:
 

The relative concentrations of coenzymes in the cell encourage binding of the appropriate coenzyme. Since NAD+ and NADH are catabolic coenzymes, the NAD+ concentration in the cell needs to be much greater than the NADH concentration because catabolic reactions are most often oxidation reactions. The opposite is true of NADP+ and NADPH. These are anabolic coenzymes that are predominantly reduction reactions which require a higher concentration of NADPH.

 

Section:


17.5


33)
 

How does NAD+ serve as a catalyst in oxidation reactions?

 

  1. A)

 

It accepts a hydride ion at the 4-position of its pyridine ring.

 

  1. B)

 

It accepts a hydride ion at the amide carbonyl group at the 3-position.

 

  1. C)

 

It accepts a proton at the 4-position of its pyridine ring.

 

  1. D)

 

It accepts a proton at the amide carbonyl group at the 3-position.

 

  1. E)

 

none of the above

 

Answer:
 

A

 

Section:


17.5


34)
 

What are the products obtained from the reaction of NADH with FMN catalyzed by NADH dehydrogenase as shown below?

 

NADH + FMN   ?  +  ?

 

  1. A)

 

NAD+ + FMNH2

 

  1. B)

 

NAD+ + FMNH

 

  1. C)

 

NAF + DHN

 

  1. D)

 

NAF + DNH2

 

  1. E)

 

N2A2D2 + FMNH2

 

Answer:
 

A

 

Section:


17.5 and 17.6


35)
 

At what position on the following coenzyme (FAD/FMN) will oxidation-reduction reactions take place?

 

 

 

  1. A)

 

6

 

  1. B)

 

2

 

  1. C)

 

3

 

  1. D)

 

4

 

  1. E)

 

5

 

Answer:
 

E

 

Section:


17.6


36)
 

Explain what is meant by a prosthetic group. Give an example.

 

Answer:
 

A tightly bound coenzyme is known as a prosthetic group.

Ex.

Flavin adenine dinucleotide (FAD) or

Flavin mononucleotide (FMN)

 

Section:


17.6


37)
 

Propose a mechanism for the following reaction.

 

 

 

Answer:
 

 

 

 

Section:


17.6


38)
 

Which of the following is thiamine?

 

  1. A)

 

vitamin B12

 

  1. B)

 

vitamin C

 

  1. C)

 

vitamin B1

 

  1. D)

 

vitamin B6

 

  1. E)

 

vitamin E

 

Answer:
 

C

 

Section:


17.7


39)
 

Which of the following is/are the coenzyme(s) formed from the vitamin thiamine (B1)?

 

  1. A)

 

TPP

 

  1. B)

 

CoASH

 

  1. C)

 

PLP

 

  1. D)

 

THF

 

  1. E)

 

FAD

 

Answer:
 

A

 

Section:


17.7


40)
 

Which of the following substrates requires the coenzyme thiamine pyrophosphate (TPP) for catalyzing its decarboxylation reaction?

 

  1. A)

 

 

 

 

  1. B)

 

 

 

 

  1. C)

 

 

 

 

  1. D)

 

 

 

 

  1. E)

 

 

 

 

Answer:
 

B

 

Section:


17.7


41)
 

Which of the following statements best describes what an electron sink is?

 

  1. A)

 

a free radical initiator for enzyme catalysis

 

  1. B)

 

a site for electron localization

 

  1. C)

 

a site for electron delocalization

 

  1. D)

 

a site that donates electrons for enzyme catalysis

 

  1. E)

 

a site that accepts electrons for enzyme catalysis

 

Answer:
 

C

 

Section:


17.7


42)
 

In addition to TPP, which of the following coenzymes is/are required to facilitate the following reaction?

 

 

 

  1. A)

 

Lipoate

 

  1. B)

 

Coenzyme A

 

  1. C)

 

FAD

 

  1. D)

 

NAD+

 

  1. E)

 

all of the above

 

Answer:
 

E

 

Section:


17.7


43)
 

Which of the following coenzymes is required for the enzyme catalyzed reaction shown below?

 

transketolase

Xylose-5-P + Ribose-5-P              Glyceraldehyde-3-P + Sedoheptulose-7-P

 

 

  1. A)

 

TPP

 

  1. B)

 

PLC

 

  1. C)

 

THF

 

  1. D)

 

NADH

 

  1. E)

 

NADPH

 

Answer:
 

A

 

Section:


17.7


44)
 

Propose a mechanism for the following reaction.

 

 

 

Answer:
 

 

 

 

Section:


17.7


45)
 

Which of the following vitamins catalyzes acyl transfer reactions and requires CoASH as a coenzyme?

 

  1. A)

 

niacin

 

  1. B)

 

thiamine

 

  1. C)

 

vitamin B12

 

  1. D)

 

lipoate

 

  1. E)

 

panthothenate

 

Answer:
 

E

 

Section:


17.7


46)
 

Which of the following reactions does the coenzyme biotin catalyze?

 

  1. A)

 

decarboxylation of an -keto acid

 

  1. B)

 

decarboxylation of an -carboxy acid

 

  1. C)

 

carboxylation of an -carboxy acid

 

  1. D)

 

decarboxylation of a carbon adjacent to an ester or keto group

 

  1. E)

 

carboxylation of a carbon adjacent to an ester or keto group

 

Answer:
 

E

 

Section:


17.8


47)
 

Which of the following are required species for biotin-requiring enzymes?

 

  1. A)

 

ATP

 

  1. B)

 

Mg+2

 

  1. C)

 

HCO3-

 

  1. D)

 

A and B

 

  1. E)

 

A, B and C

 

Answer:
 

E

 

Section:


17.8


48)
 

Which of the following is the sequence of steps followed by biotin-requiring enzymes, as listed below?

 

  1. Transfer of the carboxy group from carboxybiotin to the substrate
  2. Activation of bicarbonate by ATP

III.    Formation of carboxybiotin

 

  1. A)

 

I, II, III

 

  1. B)

 

I, III, II

 

  1. C)

 

II, I, III

 

  1. D)

 

II, III, I

 

  1. E)

 

III, II, I

 

Answer:
 

D

 

Section:


17.8


49)
 

What does the term Pyridoxal stand for?

 

  1. A)

 

Pyridine aldehyde

 

  1. B)

 

Pyrrol oxyaldehyde

 

  1. C)

 

Pyrrolidine oxyaldehyde

 

  1. D)

 

Peroxy aldehyde

 

  1. E)

 

Pyrimidoxy aldehyde

 

Answer:
 

A

 

Section:


17.9


50)
 

Which of the following reactions of amino acids is not catalyzed by PLP-requiring enzymes?

 

  1. A)

 

decarboxylation

 

  1. B)

 

transamination

 

  1. C)

 

, -elimination

 

  1. D)

 

-keto esterification

 

  1. E)

 

C-C bond cleavage

 

Answer:
 

D

 

Section:


17.9


51)
 

Which of the following reactions is called an , -elimination of an amino acid?

 

 

 

  1. A)

 

I

 

  1. B)

 

II

 

  1. C)

 

III

 

  1. D)

 

IV

 

  1. E)

 

V

 

Answer:
 

B

 

Section:


17.9


52)
 

Show the transimination (trans-Schiffization) reaction that happens in all PLP-requiring enzymes in which the amino acid substrate forms a Schiff base with PLP, thereby freeing the lysine side chain.

 

Answer:
 

 

 

 

Section:


17.9


53)
 

Which of the following is/are water-soluble vitamins?

 

  1. A)

 

vitamin B12

 

  1. B)

 

riboflavin (vitamin B2)

 

  1. C)

 

thiamine (vitamin B1)

 

  1. D)

 

pyridoxine (vitamin B6)

 

  1. E)

 

all of the above

 

Answer:
 

E

 

Section:


17.6, 17.7, 17.9, and 17.10


54)
 

Which of the following statements is not true about the structure of vitamin B12?

 

  1. A)

 

The structure was determined by Dorothy Hodgkin in 1955 using X-ray crystallography.

 

  1. B)

 

The structure has an adenosyl group.

 

  1. C)

 

The structure has a cyano group, HO-, or H2O.

 

  1. D)

 

The cyano group is coordinated to cobalt.

 

  1. E)

 

The structure cannot be synthesized by plants and animals.

 

Answer:
 

B

 

Section:


17.10


55)
 

Which of the following best represents the chemical reaction catalyzed by B12-dependent enzymes?

 

  1. A)

 

 

 

 

  1. B)

 

 

 

 

  1. C)

 

 

 

 

  1. D)

 

 

 

 

  1. E)

 

 

 

 

Answer:
 

A

 

Section:


17.10


56)
 

Propose a mechanism for the following coenzyme B12-dependent enzyme-catalyzed reaction.

 

 

 

Answer:
 

 

 

 

Section:


17.10


57)
 

Which of the following statements is not true about the coenzyme tetrahydrofolate (THF)?

 

  1. A)

 

There are six different THF-coenzymes.

 

  1. B)

 

The coenzyme is used by enzyme-catalyzing reactions that donate a group containing a single carbon to their substrate.

 

  1. C)

 

THF results from the reduction of two double bonds of the precursor vitamin (folate).

 

  1. D)

 

Mammals synthesize the vitamin (folate) but bacteria cannot.

 

  1. E)

 

Homocysteine methyl transferase and glycinamide ribonucleotide are examples of enzymes that require THF-coenzyme.

 

Answer:
 

D

 

Section:


17.11


58)
 

The thymine molecule used for the biosynthesis of DNA is synthesized from uracil as shown below.

 

The structure of dTMP is a methylated dUMP. What is the structure of dTMP?

 

 

 

  1. A)

 

I

 

  1. B)

 

II

 

  1. C)

 

III

 

  1. D)

 

IV

 

  1. E)

 

V

 

Answer:
 

E

 

Section:


17.11


59)
 

Which of the following statements is/are true about 5-fluorouracil?

 

 

 

  1. A)

 

It is an anticancer drug.

 

  1. B)

 

It inhibits the enzyme thymidylate synthase.

 

  1. C)

 

It is an example of a mechanism-based inhibitor.

 

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