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Biochem > problem roulette exam 4 > Flashcards

problem roulette exam 4 Flashcards

1
Q

Which of the following dehydrogenation reactions do NOT contribute NADH to Complex I?

Isocitrate dehydrogenase

a-ketoglutarate dehydrogenase

Malate dehydrogenase

acyl-CoA dehydrogenase

glutamate dehydrogenase

A

acyl-CoA dehydrogenase

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2
Q

Which enzyme passes electrons directly or indirectly to coenzyme Q without pumping protons?

Glycerol-3-phosphate dehydrogenase

All options are correct

Succinate dehydrogenase

Acyl-CoA dehydrogenase

A

All options are correct

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3
Q

From the choices below, select the one which is NOT shared between oxidative phosphorylation and photophosphorylation

involvement of cytochromes.

proton pumping across a membrane to create electrochemical potential.

use of iron-sulfur proteins.

chlorophyll.

participation of quinones.

A

chlorophyll

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4
Q

The action of the enzyme that catalyzes this reaction (in the direction indicated) is likely to be fully active in the ________ during __________.
The liver, after a meal

The liver, starvation

The muscle, starvation

The liver, intense exercise

The muscle, intense exercise
Submit

A

The liver, after a meal

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5
Q

Glutamate is metabolically converted to α-ketoglutarate and NH4+ by a process described as:

deamination.

oxidative deamination.

transamination.

reductive deamination.

hydrolysis.

A

oxidative deamination.

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6
Q

Fully reduced Electron Transferring Flavoprotein passes its electrons to Coenzyme Q. In what metabolic pathway was ETF reduced by an adenine nucleotide electron carrier?

Glyoxylate Pathway

Pentose Phosphate Pathway

Glycolysis

Beta-oxidation of fatty acids

Kreb’s Cycle

A

Beta-oxidation of fatty acids

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7
Q

Under times of metabolic stress, what is the correct order of use of BioMolecules in catabolic pathways to ensure enough energy is produced to get through the stress?

Monosaccharides, fatty acids, polysaccharides, amino acids, triglycerides

Polysaccharides, monosaccharides, triglycerides, amino acids.

Fatty acids, monosaccharides, triglycerides, amino acids

Fatty acids, monosaccharides, polysaccharides, amino acids, proteins

Monosaccharides, polysaccharides, triglycerides, amino acids.

A

Monosaccharides, polysaccharides, triglycerides, amino acids.

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8
Q

During oxidative phosphorylation, the proton motive force that is generated by electron transport is used to:

reduce O2 to H2O.

generate the substrates (ADP and Pi) for the ATP synthase.

create a pore in the inner mitochondrial membrane.

induce a conformational change in the ATP synthase.

oxidize NADH to NAD+.

A

induce a conformational change in the ATP synthase.

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9
Q

in the mitochondria a motive force for ATP/ADP exchange is the __________ and for importing inorganic phosphate into the matrix is the ___________.

A

membrane potential (negative in the matrix), proton gradient

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10
Q

Where in the chloroplast is Plastocyanin located?

On the lumenal side of the stromal membranes

On the stromal side of the membranes

On the outside of the outer membrane

On the Inside of the outer membrane

On the cytoplasmic side of the chloroplast

A

On the lumenal side of the stromal membranes

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11
Q

How many carbon dioxide molecules are fixed in the Calvin Cycle in order to produce one glyceraldehyde 3-phosphate?

3

1

None, the Calvin Cycle does not fix carbon

2

4

A

3

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12
Q

Which of the following statements about aminotransferases is true?

The PLP cofactor alone can accelerate the rate of the reaction almost as much as the full PLP-enzyme complex

The aminotransferase reaction is essentially irreversible

The enzyme requires that both the donor amino acid and the acceptor a-ketoacid are bound simultaneously

A single aminotransferase is able to catalyze amino group transfer to a-ketoglutarate from any of the 20 amino acids

PLP is covalently linked to the enzyme for the entire reaction cycle

A

The PLP cofactor alone can accelerate the rate of the reaction almost as much as the full PLP-enzyme complex

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13
Q

The active site of the first enzyme in carbon fixation in C3 plants coordinates a magnesium ion. Which amino acid is NOT involved in this coordination?

All of these amino acids coordinate the magnesium.

His

Lys

Asp

Glu

A

His

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14
Q

During the initial charging step of fatty synthesis, a(n) ________ group is covalently linked to a _________ of acyl carrier protein.

Malonyl; biotin prosthetic group

Malonyl; cysteine

Acetyl; cysteine

Malonyl; phosphopantetheine prosthetic group

Acetyl; biotin prosthetic group

Acetyl; phosphopantetheine prosthetic group

A

Malonyl; phosphopantetheine prosthetic group

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15
Q

In the bacterial pheophtyin-quinone reaction centers, how are P870’s electrons replaced?

From a tyrosine radical

Oxidation of H2S

Oxidation of water by the oxygen-evolving complex

Oxidation of NADH

They do not have to be replaced because this reaction center is in a cyclic electron transfer pathway.

A

They do not have to be replaced because this reaction center is in a cyclic electron transfer pathway.

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16
Q

Which prosthetic group is found on all aminotransferases?

Thiamine pyrophosphate (TPP)

Flavin mononucleotide (FMN)

Flavin adenine nucleotide (FAD)

Lipoate

Pyridoxal phosphate (PLP)

A

Pyridoxal phosphate (PLP)

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17
Q

Glutamine synthetase converts _____ to _____ whereas glutamate synthase converts ____ to _____.

glutamate; glutamine; α-ketoglutarate; glutamate

asparagine; glutamine; α-ketoglutarate; glutamate

α-ketoglutarate; glutamine; oxaloacetic acid; glutamate

α-ketoglutarate; glutamine; α-ketoglutarate; glutamate

formate; glutamine; ammonia; glutamate
Submit

A

glutamate; glutamine; α-ketoglutarate; glutamate

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18
Q

If all the Acytyl-CoA used to synthesize a palmitate (C16) fatty acid are in the mitochondria, there will be an additional expense in fatty acid synthesis of up to ________.

2 ATP

8 ATP

16 ATP

7 ATP

14 ATP

A

16 ATP

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19
Q

Cholesterol is synthesized from:

lipoic acid.

malate.

choline.

oxalate.

acetyl-CoA.

A

acetyl-CoA.

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20
Q

Which of the following electron carriers is lipid soluble?

All of these

Plastocyanin

Flavin nucleotides

Ubiquinone

Cytochrome c

A

Ubiquinone

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21
Q

In the mitochondrial shuttles, NADH and acetyl-CoA are carried across the mitochondrial membrane as “equivalents.” NADH is carried across the membrane as _________, and acetyl-CoA is carried across the membrane as _______.

citrate; malate

malate; pyruvate

pyruvate; citrate

citrate; malate

malate; citrate
Submit

A

malate; citrate

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22
Q

All aminotransferases have the same prosthetic group. Please identify it from the list below.

FAD

Vitamin B12

Coenzyme A

Biotin

Pyridoxal phosphate

A

Pyridoxal phosphate

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23
Q

Which of the following is NOT required for the synthesis of Cholesterol from its initial precursor?

Coenzyme A

NADPH

ATP

Carbon dioxide

A

Carbon dioxide

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24
Q

What is the important intermediate at a branch point that leads to either AMP or GMP synthesis?

AICAR

Inosinate

Folate

Chorismate

Xanthylate

A

Inosinate

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25
Q

The first intermediate in cholesterol synthesis which contains all the carbon atoms which will eventually form the four fused ring cholesterol backbone is

Activated Isoprene

acetyl-CoA

squalene

mevalonate

lanosterol

A

squalene

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26
Q

The following enzyme in the palmitate synthesis pathway is positively regulated by citrate:

HMG-CoA reductase

Acetyl-CoA carboxylase

Malonyl/Acetyl-CoA-ACP transferase

Enoyl-ACP reductase

Ketoacyl synthase

A

Acetyl-CoA carboxylase

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27
Q

Which of the following molecules are negative regulators of fatty acid synthesis?

Citrate
Epinephrine
Palmityl-CoA

II and III only

None of these

I only

I and II only

III only

A

II and III only

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28
Q

The following molecules are produced by the first phase of the Q cycle:

Ubiquinol (fully reduced)
Semiquinone radical
Ubiquinone (fully oxidized)

II and III only

I only

I, II, and III

I and II only

I and III only

A

II and III only

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29
Q

When the [NADPH]/[NADP+] ratio in plants is high, photophosphorylation is primarily cyclic. What is/are the major product(s) of photophosphorylation in this circumstance?

ATP + NADPH

ATP

O2

NADPH

A

ATP

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30
Q

After each round of acyl chain elongation, the new acyl chain moves from

Detroit to Miami Beach when the snow starts

ACP to KS

Acetyl CoA to Malonyl CoA

ACP to Malonyl CoA

KS to ACP

A

ACP to KS

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31
Q

In cholesterol synthesis, the first molecule in the synthetic pathway that possesses a sterol nucleus is:

Lanosterol

Isoprene

Mevalonate

Squalene

Cholesterol

A

Lanosterol

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32
Q

Which of the following is involved in mitochondrial electron transport and not in electron transport in chloroplasts?

Cytochrome c oxidase

Plastoquinone

Cytochrome B6/f

Coenzyme Q

Iron-Sulfur Centers (Clusters)

A

Cytochrome c oxidase

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33
Q

Which of the following would NOT supply NADPH (from NADP+) that could be used for anabolic pathways?

Malic Enzyme

All of the above produce NADPH

Beta-Oxidation

Photosynthesis

Pentose Phosphate Pathway

A

Beta-Oxidation

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34
Q

Head-group Exchange is a strategy used for the synthesis of

Membrane phospholipids

Leukotrienes

Cholesterol

Triacylglycerols

Palmitate

A

Membrane phospholipids

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35
Q

In Photosystem II, which of the following directly oxidizes the Mn4CaO5 cluster?

A tyrosine radical

Water

A special chlorophyll in the P680 reaction center

An exciton

Oxygen (O2)

A

A tyrosine radical

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36
Q

What prosthetic group is required by acetyl-CoA carboxylase, covalently linked to a Lys residue?

Vitamin B12

Biotin

FADH2

Cardiolipin

Tetrahydrofolate

A

Biotin

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37
Q

Which of the following chemical transformations regulates Rubisco?

Decarboxylation

Phosphorylation/dephosphorylation

Reduction/Oxidation

Carbamoylation

Protonation

A

Carbamoylation

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38
Q

Coenzyme Q and cholesterol synthesis share which common precursor?

Squalene

NADH

Malonyl-CoA

Activated Isoprene

Lanosterol

A

Activated Isoprene

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39
Q

The fixation of atmospheric nitrogen is costly with respect to energy, and only certain organisms undergo nitrogen fixation. How many molecules of ATP are required to fix one N2 into 2 NH4+?

4

2

32

8

16

A

16

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40
Q

The synthesis of arginine starts with the amino acid , and uses reactions from the .

glutamine; citric acid cycle

glutamine; urea cycle

glutamate; urea cycle

glutamate; citric acid cycle

glutamate; glyoxylate cycle

A

glutamate; citric acid cycle

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41
Q

Succinate dehydrogenase is dysfunctional in a species of garden slug. While its metabolism is compromised on a number of levels, it can still undergo oxidative phosphorylation. What is the maximal P/O ratio for these organisms if NADH is used as an electron source?

1.5

1

2

4

2.5

A

2.5

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42
Q

Which of the following enzymes is present in the Calvin cycle, but not present in either glycolysis or the pentose phosphate pathway?

Aldolase

Transketolase

Ribulose 5-phosphate kinase

Phosphoglycerate kinase

Transaldolase

A

Ribulose 5-phosphate kinase

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43
Q

For the synthesis of one molecule of palmitate, the fatty acid synthase complex (in isolation) consumes the following reagents:

8 malonyl CoA, 14 NADPH

1 acetyl CoA, 7 malonyl CoA, 16 NADPH

1 acetyl CoA, 7 malonyl CoA, 14 NADPH

8 acetyl CoA, 14 NADPH

8 malonyl CoA, 16 NADPH

A

1 acetyl CoA, 7 malonyl CoA, 14 NADPH

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44
Q

Which of the following is a role for the transmembrane domain of the ATP Synthase at the end of the Respiratory Chain?

Contains the ADP/ATP binding site

Contains the catalytic domain for the ATPase

Contains the FMN that provides protons for ATP synthesis

Contains the proton pore

Contains the electron transport pore

A

Contains the proton pore

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45
Q

Many plants synthesize several different photopigments. With respect to photophosphorylation, the reason for this is:

Photopigments with different absorption maxima can absorb photons from the entire visible spectrum

If the reactants to synthesize chlorophyll are not available, other photopigments can replace chlorophyll in the photosystems

This provides several alternate routes of electron entry to the photosystems

Plants synthesize different photopigments depending on the nutrients available

The different standard reduction potentials of different photopigments allow them to operate under a variety of different redox conditions

A

Photopigments with different absorption maxima can absorb photons from the entire visible spectrum

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46
Q

The Oxygen Evolving Complex produces ____ electrons and pumps ____ H+ into the thylakoid lumen for every O2 produced.

2, 8

4, 4

8, 8

4, 2

2, 4

A

4, 4

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47
Q

Consider the following diagram showing feedback inhibition in the biosynthesis of amino acids. Which of the following types of regulation are observed in the lysine biosynthesis pathway?

Concerted inhibition
Sequential inhibition
Enzyme multiplicity

I and III

III only

I and II

I only

I, II and III

A

I, II and III

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48
Q

What structure, molecule or system replenishes the “electron hole” created in the P680 Reaction Center due to exciton transfer?

P700

FADH2

NADH

Oxygen evolving complex

Ferridoxin

A

Oxygen evolving complex

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49
Q

The following enzyme is the most important site of regulation for fatty acid biosynthesis:

Acetyl-CoA carboxylase

Ketoacyl reductase

Ketoacyl synthase

Malonyl/Acetyl-CoA-ACP transferase

Enoyl-ACP reductase

A

Acetyl-CoA carboxylase

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50
Q

The carbon skeletons of ketogenic amino acids may be incorporated directly into ____________, whereas the carbon skeletons of glucogenic amino acids may be incorporated directly into _____________.

LaTeX: \alphaα
-Ketoglutarate; Citrate and Malate

Malonyl-CoA; Citrate and DHAP

LaTeX: \alphaα
-Ketoglutarate; Acetyl-CoA

Succinyl-CoA and LaTeX: \alphaα
-Ketoglutarate; Acetyl-CoA

Acetyl-CoA; Succinyl-CoA and LaTeX: \alphaα
-Ketoglutarate

A

Acetyl-CoA; Succinyl-CoA and α
-Ketoglutarate

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51
Q

Which important intermediate of cholesterol synthesis, beginning with acetate, is itself transformed by three successive phosphoryl group transfer reactions?

Acetoacetyl-CoA

Isoprenes

Mevalonate

Squalene

Lanosterol

A

Mevalonate

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52
Q

CMP, UMP, and TMP all have _____ as a common precursor.

glutamine

aspartate

adenosine

inosine

S-adenosyl methionine

A

aspartate

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53
Q

Which of the following terms describes leptin?

Steroid hormone

Paracrine hormone

Eicosanoid hormone

Autocrine hormone

Endocrine hormone

A

Endocrine hormone

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54
Q

Free nitrogen (ammonia) can be incorporated into ___________ yielding __________ at a cost of ______________.

alpha -ketoglutarate, glutmate, 1 ATP

aspartate, asparagine, 1 ATP

glutamine, glutamate, 1 ATP

glutamate, glutamine, 1 ATP

glutamate, glutamine, 1 NAD(P)H

A

glutamate, glutamine, 1 ATP

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55
Q

If all the electrons used in the reductive steps of the synthesis of a palmitate (C16) fatty acid were instead fed into the respiratory chain for ATP synthesis, there could be a net production of up to _______ ATP.

20

17.5

35

40

28

A

35

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56
Q

Which of the following amino acids is the main carrier of nitrogen through the bloodstream during normal metabolic load?

Glu

Asn

Gln

Arg

Ala

A

Gln

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57
Q

In the urea cycle, fumarate is produced by the following enzyme:

Arginase

Argininosuccinate synthetase

Argininosuccinase

Carbamoyl phosphate synthetase

Ornithine transcarbamoylase

A

Argininosuccinase

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58
Q

Which of the following molecules in photophosphorylation is NOT an integral membrane protein?

Light Harvesting Complex

Photosystem I

Photosystem II

Cytochrome b6f complex

Plastocyanin

A

Plastocyanin

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59
Q

Which of the following statements describes insulin?

A “bottom-up” metabolic regulator that leads to a decrease in blood glucose levels

A peptide hormone that signals that blood glucose is low

A “top-down” metabolic regulator that leads to a decrease in blood glucose levels

A “bottom-up” metabolic regulator that signals that blood glucose is low

A “top-down” metabolic regulator that leads to an increase in blood glucose levels

A

A “bottom-up” metabolic regulator that leads to a decrease in blood glucose levels

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60
Q

Amytal is a barbituate that inhibits Complex I of the electron transport chain. Which of the following might happen if amytal is present in mitochondria:

Increased levels of NADH
ATP is not synthesized
QH2 is not produced

II and III only

II only

I, II, and III

I and II only

I only

A

I only

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61
Q

Pyrimidine nucleotides are synthesized de novo from what amino acid and using what extra source of energy?

Asp and ATP

Asn and NADPH

Ser and ATP

Glu and NADH

Asp and GTP

A

Asp and ATP

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62
Q

An amino acid that does not derive its carbon skeleton, at least in part, from α-ketoglutarate is:

threonine.

arginine.

proline.

glutamate.

glutamine.

A

threonine.

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63
Q

Electrons in photosystem I come from _____; electrons in photosystem II come from _____.

O2; Photosystem I

H2O; Photosystem I

Photosystem II; H2O

Photosystem II; O2

NADPH, Photosystem 1

A

Photosystem II; H2O

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64
Q

On which side of the chloroplast membrane is the ATP Synthase active site?

On the cytoplasmic side

On the lumenal side of the stromal membranes

On the Inside of the outer membrane

On the outside of the outer membrane

On the stromal side of the membranes

A

On the stromal side of the membranes

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65
Q

The molecule exported from the mitochondria to feed into fatty acid synthesis also regulates ___________and ______________.

Fatty acid synthase and PFK-1

carnitine acyltransferase and acetyl-CoA carboxylase

Fatty acid synthase and acetyl-CoA carboxylase

PFK-1 and acetyl-CoA carboxylase

PFK-1 and carnitine acyltransferase

A

PFK-1 and acetyl-CoA carboxylase

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66
Q

The Oxygen Evolving Complex of Photophosphorylation

Uses a Manganese Complex rather than Magnesium to remove electrons from molecular oxygen

Passes 4 electrons to P680+ and passes 4 protons to the chlorplast stroma

Passes 4 electrons to P700+

Links PSII with PSI through a pair of Cytochrome molecules

Accepts electrons and produces molecular oxygen, plus pumps 4 protons to the thylakoid lumen

A

Accepts electrons and produces molecular oxygen, plus pumps 4 protons to the thylakoid lumen

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67
Q

Which of the following nucleic acid derivatives is used in large amounts for fatty acyl chain synthesis?

FMN

NADP+

NADH

ACP

NADPH

A

NADPH

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68
Q

Nitrogen disposal via the urea cycle involves the input of ATP at two places, including a key adenylyl transfer reaction. What is the enzyme that catalyzes the adenylyl transfer?

Ornithine transcarbamoylase

Carbamoyl phosphate synthetase I

Argininosuccinate synthetase

Arginosuccinase

A

Argininosuccinate synthetase

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69
Q

Some herbicides inhibit electron transfer to plastocyanin. Which of the following is a likely effect of this herbicide?

ATP synthesis continues, but NADPH is not formed

NADPH synthesis continues, but ATP is not formed

ATP synthesis and NADPH synthesis are both prevented

The oxygen-evolving complex cannot donate electrons to Photosystem II

Excessive heat is generated, causing enzyme denaturation

A

ATP synthesis continues, but NADPH is not formed

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70
Q

In certain tissues, the yield of ATP from _______________ is reduced due to the use of the ___________________ rather than the _________________ for transport of electrons into the respiratory chain.

FADH2, glycerol 3-phosphate shuttle, malate-aspartate shuttle

NADH, glycerol 3-phosphate shuttle, malate-aspartate shuttle

FADH2, malate-aspartate shuttle, glycerol 3-phosphate shuttle

NADH, malate-aspartate shuttle, glycerol 3-phosphate shuttle

NADH, glyceraldehyde-3-phoshate shuttle, malate-aspartate shuttle

A

NADH, glycerol 3-phosphate shuttle, malate-aspartate shuttle

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71
Q

Which of the following is NOT a fate of glucose-6-phosphate in the fed state?

Synthesis of ribulose-5-phosphate

Conversion to glycogen

Oxidation via glycolysis, Kreb’s cycle, and the respiratory chain

Dephosphorylation to glucose

Conversion to acetyl CoA for fatty acid synthesis

A

Dephosphorylation to glucose

72
Q

Which of the following characterizes C4 plants?

Low starch concentration in leaf cells, low light conditions, wet and humid environment

High photorespiration rate, high metabolic rates, high water loss

Low water loss, growth in high light/tropical conditions, high photosynthetic rates

High water loss, high photosynthetic rates, high metabolic rates

A

Low water loss, growth in high light/tropical conditions, high photosynthetic rates

73
Q

About how many protons are passively transported through the F1/Fo complex in order to phosphorylate one molecule of ADP? (Assume 9 c subunits in Fo.)

4

2

2.5

3.5

3

A

3

74
Q

Which of the following is TRUE about the reaction shown?

This reaction takes place in the cytosol of liver cells

This reaction is catalyzed by a transcarbamoylase

The enzyme that catalyzes this reaction is not a major regulatory point

Glutamate is an allosteric activator of the enzyme that catalyzes this reaction

This reaction accounts for the consumption of half of the high energy phosphoryl groups required to convert ammonium to urea

A

This reaction accounts for the consumption of half of the high energy phosphoryl groups required to convert ammonium to urea

75
Q

When the [NADPH]/[NADP+] ratio in plants is low, photophosphorylation is primarily non-cyclic. What is/are the major product(s) of photophosphorylation in this circumstance?

I. ATP

II. NADPH

III. O2

All of these

II and III

I only

II only

I and III

A

II and III

76
Q

For which group of molecules below is Inosinate (IMP) an important intermediate?

Amino Acids derived from 3-phosphoglycerate

the deoxyribonucleic acids

Purine nucleotides

Pyrimidine nucleotides

Amino acids derived from alpha-ketoglutarate

A

Purine nucleotides

77
Q

Consider the following Z-diagram. Which of the following statements is NOT true?P680* has a higher electron affinity than P700*

The manganese cluster of the oxygen complex can be oxidized four times before it oxidizes water

Pheophytin (pheo) has a higher electron affinity than plastocyanin

Δ G of electron transfer from Fd to cytochrome b6f complex is negative

Without absorption of a photon, promotion of an electron from P680 to P680* would have a positive Δ G

A

Pheophytin (pheo) has a higher electron affinity than plastocyanin

78
Q

If an uncoupler is added to the mitochondrial membrane, which of the following would NOT be an expected consequence?

An increase in temperature

An increase in the electrical potential across the mitochondrial membrane

A decrease in the measured P/O ratio

An increase in oxygen utilization

A decrease in the amount of ATP produced per mole of glucose consumed

A

An increase in the electrical potential across the mitochondrial membrane

79
Q

Place the following electron-carriers into the proper order as found in plant chloroplasts.

1) Cytochrome b6f complex
2) Plastocyanin
3) P700
4) P680
5) NADPH

2, 1, 3, 4, 5

4, 2, 5, 1, 3

1, 3, 4, 2, 5

4, 1, 2, 3, 5

3, 2, 4, 1, 5

A

4, 1, 2, 3, 5

80
Q

What is the P/O ratio for mitochondrial oxidation using NADH?

2

1.5/2/.5

2.5

3

3/2

A

2.5

81
Q

The urea cycle involves the movement of the following two molecules across the mitochondrial membrane:

Carbamoyl phosphate and ornithine

Arginine and ornithine

Citrulline and ornithine

Carbamoyl phosphate and citrulline

Citrulline and arginine

A

Citrulline and ornithine

82
Q

Expressing thermogenin (UCP1) generates heat because:

None of the options are correct.

It uncouples electron transport from pumping protons, causing the electrons to release their potential energy as heat.

It uncouples F1 and Fo causing rapid ATP hydrolysis which releases heat.

It uncouples Oxygen reduction from proton transport.

It uncouples proton transport from ATP production, causing the protons to release their potential energy as heat.

A

It uncouples proton transport from ATP production, causing the protons to release their potential energy as heat.

83
Q

Fatty acid synthesis requires _____________ for each round, while beta oxidation yields _______________ for each round.

NADPH; FADH2

NADPH; NADH

2 NADPH; 1 FADH2 and 1 NADH

1 FADH2 and 1 NADH; 2 NADH

2 NADH; 1 FADH2 and 1 NADPH

A

2 NADPH; 1 FADH2 and 1 NADH

84
Q

What is the result of activation of Complex I of the Respiratory Chain?

4 Protons are pumped from the intermembrane space to the Matrix

NADH gets reduced

Electrons accepted from NADH are passed to FAD

QH2 becomes oxidized

4 protons are pumped from the matrix to the intermembrane space

A

4 protons are pumped from the matrix to the intermembrane space

85
Q

_______________ are synthesized as inactive _______________ and secreted to the stomach where _____________ activates them for degradation of dietary amino acids.

proteases, zymogens, phosphorylation

proteases, zymogens, low pH

zymogens, proteases, low pH

zymogens, proteases, high pH

proteases, zymogens, phosphorylation

A

proteases, zymogens, low pH

86
Q

Carbamoyl phosphate is an important intermediate in the synthesis of which of the following groups of molecules?

Amino acids derived from Pyruvate

Aromatic amino acids

Deoxyribonucleotides

Pyrimidines

Purines

A

Pyrimidines

87
Q

The cellular ATP/ADP ratio controls the rate of:

Oxidative phosphorylation
The TCA cycle
Glycolysis

I and II

I and III

I, II and III

I only

II and III

A

I, II and III

88
Q

Chemical uncouplers of photophosphorylation have been identified. Like mitochondrial uncouplers, these agents cause an increase in temperature of plant tissue. Which of the following is another likely metabolic consequence of a partial uncoupler of photophosphorylation:

NADPH synthesis is halted

Protons accumulate in the thylakoid lumen

Via regulatory mechanisms, the plant increases the ratio of cyclic to non-cyclic pathways

Protons move more rapidly from stroma to the thylakoid lumen

Oxygen consumption increases

A

Via regulatory mechanisms, the plant increases the ratio of cyclic to non-cyclic pathways

89
Q

The major pathways of Ammonium Assimilation lead to the synthesis of which one of the following amino acids?

Ser

Phosphoenolpyruvate

Gly

Asp

Gln

A

Gln

90
Q

The Glucose-Alanine Cycle performs what specific role in metabolism?

Transport of Urea to the Urinary tract

Production of ATP and NADH when the Citric Acid Cycle is low on intermediates

Catabolism of Glucose to produce the precursors for several amino acids, including Ala

Transport of amino groups to the liver in a non-toxic form

Transfer of Ala to smooth muscle where it is converted to Oxaloacetate

A

Transport of amino groups to the liver in a non-toxic form

91
Q

What molecule is central to carbohydrate (i.e. sugar) metabolism in the liver, being at a crossroads of at least 5 important possible fates and whose concentration controls regulatory enzyme activity in each of those fates?

Glutamate

Acetate

Glucose 6-phosphate

NADPH

ATP

A

Glucose 6-phosphate

92
Q

Which of the following statements about aminotransferases is true?

PLP is covalently linked to the enzyme for the entire reaction cycle

The PLP cofactor is always bound to the enzyme with a covalent bond

A single aminotransferase is able to catalyze amino group transfer to a-ketoglutarate from any of the 20 amino acids

The enzyme requires that both the donor amino acid and the acceptor a-ketoacid are bound simultaneously

The aminotransferase reaction is readily reversible

A

The aminotransferase reaction is readily reversible

93
Q

How many malonyl-CoA and acetyl-CoA are necessary to produce 1 molecule of Palmitate?

1 Malonyl-CoA and 7 Acetyl-CoA

7 Malonyl-CoA and 7 Acetyl-CoA

7 Malonyl-CoA and 1 Acetyl-CoA

1 Malonyl-CoA and 8 Acetyl-CoA

1 Malonyl CoA and 8 Acetyl-CoA

A

7 Malonyl-CoA and 1 Acetyl-CoA

94
Q

A new electron carrier has been discovered. It directly passes 4 electrons to ubiqinol. How many ATPs is this carrier worth when fully charged?

1.5 ATPs

3 ATPs

6 ATPs

2 ATPs

2.5 ATPs

A

3 ATPs

95
Q

Malonyl-CoA for acyl chain synthesis is produced by acetyl-CoA carboxylase. What prosthetic group is required for this enzyme?

NADH

Biotin

Transcobalamin

Magnesium

Thiamine pyrophosphate

A

Biotin

96
Q

The component of plant reaction centers which is most analogous in function to Complex III in oxidative phosphorylation is:

Plastocyanin

Ferredoxin:NADP oxidoreductase

Cytochrome b6f complex

pheophytin

Cytochrome c2

A

Cytochrome b6f complex

97
Q

What is the result of one round of electron transport by Complex I of the Respiratory Chain?

QH2 becomes oxidized

NADH gets reduced

4 Protons are pumped from the Intermembrane space to the Matrix

4 protons are pumped from the Matrix to the intermembrane space

Electrons accepted from NADH are passed to FAD

A

4 protons are pumped from the Matrix to the intermembrane space

98
Q

The compartment of the chloroplast which is analogous to the intermembrane space of the mitochondria is:

thylakoid membrane

stroma

outer membrane

thylakoid lumen

granal stacks

A

thylakoid lumen

99
Q

What is the main regulatory mechanism on Purine Synthesis?

Feedback inhibition, mostly by monophosphates

Phosphorylation/dephosphorylation of the first enzyme of the pathway

Inhibition of the formation of AICAR

Limitation of the starting reactant, which comes from Glycolysis

Competitive inhibition by Pyrimidine diphosphates

A

Feedback inhibition, mostly by monophosphates

100
Q

Inosinate (IMP) serves as a precursor in pathways that generate which of the following?

Asp

Fumarate

NADH

Thymidine

Cytosine

A

Fumarate

101
Q

Which of the following is the proper order of electron transport between Photosystem II and Photosystem I in higher plant membranes?

Pheophytin, plastocyanin, plastoquinone

Plastoquinone, Cytochrome b6/f, plastocyanin

Chlorophyll a, plastocyanin, plastoquinone

Cytochrome Q, Cytochrome a, Cytochrome c

Plastocyanin, plastoquinone, iron-sulfur center

A

Plastoquinone, Cytochrome b6/f, plastocyanin

102
Q

A transaminase uses alpha-ketoglutarate and the molecule shown below as a substrate. The products of the reaction are glutamate and ______________.Glycerate

alpha-ketoglutarate

Oxaloacete

Carbamate

Pyruvate

A

Pyruvate

103
Q

What is the form of sulfur that is incorporated into Cys (using Serine)?

Sulfate

Sulfide

Sulfite

H2S

A

Sulfide

104
Q

Which of the following actually leaves a Photochemical Reaction Center, a critical reaction in Photophosphorylation?

A molecule of cytochrome c

An electron

A hydride ion

A molecule of oxygen (O2)

A photon of light

A

An electron

105
Q

Passing two electrons from glycerol-3-phosphate through the respiratory chain yields:

6 ATP

10 ATP

1.5 ATP

None of the other answers is correct

2.5 ATP

A

1.5 ATP

106
Q

If a plant cell chloroplast has an excess of NADPH relative to ATP, it would be logical to adjust the photosynthetic pathway such that:

(Refer to the following image if necessary.)
The light harvesting complex associates more tightly with photosystem II thus favoring the noncyclic mode.

The light harvesting complex associates more tightly with photosystem II thus favoring the cyclic mode.

The light harvesting complex associates more tightly with photosystem I thus favoring the cyclic mode.

None of these other answers would apply

The light harvesting complex associates more tightly with photosystem II thus favoring the noncyclic mode.

A

The light harvesting complex associates more tightly with photosystem I thus favoring the cyclic mode.

107
Q

The key regulatory step in cholesterol biosynthesis is catalyzed by:

Acetyl CoA carboxylase

Mevalonate 5-phosphotransferase

HMG-CoA reductase

Phosphomevalonate kinase

HMG-CoA synthase

A

HMG-CoA reductase

108
Q

The following electron carriers are capable of transporting exactly one electron except:

Ubiquinone

FeS cluster

Cytochrome c

Plastocyanin

CuA

A

Ubiquinone

109
Q

In fatty acid synthesis, the step catalyzed by fatty acid synthase immediately after the dehydration step is: (The squiggle indicates the covalent linkage to ACP).

A
110
Q

For the following two half reactions:

Cytochrome c (Fe3+) + e– LaTeX: \rightarrow cytochrome c (Fe2+) E’ (V) = 0.220

FAD + 2H+ + 2e– LaTeX: \rightarrow FADH2 E’ (V) = -0.219

We would expect the spontaneous complete reaction to be:

A

2 Cytochrome c (Fe3+) + FADH2 -> 2 cytochrome c (Fe2+) + FAD + 2H+

111
Q

Which of the following molecules is NOT used in the reaction that produces Carbamoyl Phosphate, the nitrogen carrier, in the Urea Cycle?

Bicarbonate

Ammonia

ATP

All of the above molecules are used by carbamoyl phosphate synthetase I

Coenzyme A

A

Coenzyme A

112
Q

Which is the correct path electrons follow in the oxygen evolving complex?

H2O, Tyr, Mn, P680

H2O, Mn, Tyr, P680

O2, Tyr, Mn, P680

O2, Mn, Tyr, P680

P680, Tyr, Mn, H2O

A

H2O, Mn, Tyr, P680

113
Q

In comparing fatty acid biosynthesis with β oxidation of fatty acids, which of the following statements is incorrect?

A thioester derivative of crotonic acid (trans-2-butenoic acid) is an intermediate in the synthetic path, but not in the degradative path.

Fatty acid biosynthesis uses NADPH exclusively, whereas β oxidation uses NAD+ exclusively.

The condensation of two moles of acetyl-CoA in the presence of a crude extract is more rapid in bicarbonate buffer than in phosphate buffer at the same pH; the cleavage of acetoacetyl-CoA proceeds equally well in either buffer.

Fatty acid degradation is catalyzed by cytosolic enzymes; fatty acid synthesis by mitochondrial enzymes.

A thioester derivative of D-β-hydroxybutyrate is an intermediate in the synthetic path, not in the degradative path.

A

Fatty acid degradation is catalyzed by cytosolic enzymes; fatty acid synthesis by mitochondrial enzymes.

114
Q

What amino acid serves as a reactant in most transamination reactions for amino acid synthesis?

Ala

Arg

Gln

Gly

Glu

A

Glu

115
Q

One amino acid directly involved in the purine biosynthetic pathway is:

tryptophan

aspartate.

glutamate.

leucine.

alanine.

A

aspartate

116
Q

The cellular respiration rate is regulated by ADP. This is an example of which regulatory mechanism?

Sequential Inhibition

Mass action

Acceptor control

Concerted regulation

Feedback regulation

A

Acceptor control

117
Q

For every CO2 incorporated into 3-phosphoglycerate by Rubisco, ____________ is/are consumed (not counting ribulose 1,5-bisphosphate or water).

2 ATP

no other molecules

1 NADPH

1 ATP and 1 NADPH

1 ATP

A

no other molecules

118
Q

Which of the following is an alternative route of entry into the electron transport chain that bypasses both complex I and complex II and transfers electrons directly to ubiquinone?

Malate dehydrogenase

alpha-ketoglutarate dehydrogenase

Glyceraldehyde-3-phosphate dehydrogenase

Glycerol-3-phosphate dehydrogenase

Succinate dehydrogenase

A

Glycerol-3-phosphate dehydrogenase

119
Q

What important intermediate is the first in the purine synthesis pathway that has a complete double ring structure?

AICAR

Acetolactate

Inosinate

Spermidine

Squalene

A

Inosinate

120
Q

A 30-carbon precursor of the steroid nucleus is:

lysolecithin.

farnesyl pyrophosphate.

geranyl pyrophosphate.

squalene.

isopentenyl pyrophosphate.

A

squalene

121
Q

When the following reaction occurs in peripheral tissues (non-muscle) under normal turnover of cellular amino acids (not starvation conditions), a likely fate of the product shown in the upper right is:
Oxidative deamination to immediately release the nitrogen.

Immediate entry into the Urea cycle

Incorporation of a second nitrogen (at the expense of 1 ATP) prior to export to the bloodstream.

Direct export to the bloodstream for processing in the liver

A

Incorporation of a second nitrogen (at the expense of 1 ATP) prior to export to the bloodstream.

122
Q

Which one of these is most commonly used as a reducing agent in the cell to facilitate fatty acid synthesis?

NADP+

FADH2

NAD+

NADH

NADPH

A

NADPH

123
Q

In amino acid catabolism, the first reaction for many amino acids is a(n):
decarboxylation requiring thiamine pyrophosphate (TPP).

hydroxylation requiring NADPH and O2.

transamination requiring pyridoxal phosphate (PLP).

reduction requiring pyridoxal phosphate (PLP).

oxidative deamination requiring NAD+.

A

transamination requiring pyridoxal phosphate (PLP).

124
Q

Which of the following does NOT describe a physiological consequence of high blood glucagon levels?

Polymerization of fatty acid synthetase

Decreased activity of phosphofructokinase in the liver

Inhibition of acetyl-CoA carboxylase

Increased activity of glycogen phosphorylase

Glucose released to the blood

A

Polymerization of fatty acid synthetase

125
Q

The product of arginosuccinase that does not contain nitrogen:

Directly contributes electrons to the electron transport chain

Is directly transported across the mitochondrial membrane

Directly feeds into the citric acid cycle

Can be utilized in purine biosynthesis

Can be converted into malate via the action of cytosolic fumarase for transport into the mitochondria

A

Can be converted into malate via the action of cytosolic fumarase for transport into the mitochondria

126
Q

The synthesis of DNA requires deoxyribonucleotides derived from ribonucleotides by reduction. What molecule provides the reducing equivalents for this reaction?

FADH2

NADP+

NAD+

NADPH

NADH

A

NADPH

127
Q

Consider the following diagram of absorption spectra of various pigments.

Which order is the most likely path for the flow of exciton transfer?

Lutein –> chlorophyll a –> chlorophyll b

Phycocyanin –> Phycoerythrin –> beta-carotene

beta-carotene –> phycoerythrin –> phycocyanin

chlorophyll b –> phycocyanin –> phycoerythrin

beta-carotene –> Lutein –> phycoerythrin

A

beta-carotene –> phycoerythrin –> phycocyanin

128
Q

I add an inhibitor of mitochondrial respiration that prevents electron transfer to cytochrome c. Which of the following outcomes is the most likely?

Buildup of both QH2 and NADH; decreased oxygen consumption

Buildup of QH2 but not NADH, increased oxygen consumption

Normal levels of QH2 and NADH; decreased oxygen consumption

Normal levels of QH2 and NADH; increased oxygen consumption

Buildup of QH2 but not NADH; decreased oxygen consumption

A

Buildup of both QH2 and NADH; decreased oxygen consumption

129
Q

Which pair of amino acids would you expect to have essentially identical synthesis pathways (parallel reactions, same chemistry), differing only by the identity of one of the starting substrates?

Trp, Tyr

Val, Ile

Ser, Cys

Asp, Gln

Thr, Ser

A

Val, Ile

130
Q

The overall reaction: QH2 + 2 cyt c (ox) + 2HN+ –> Q + 2cyt c (red) + 4HP+ is catalyzed by which electron transfer complex?

Complex II

Complex IV

Complex III

ATP synthase

Complex I

A

Complex III

131
Q

What product from glycogen catabolism in very active skeletal muscle is sent to the liver through the blood as a part of the Cori Cycle?

NADH

Lactate (or Lactic Acid)

Glucose

Ketone Bodies

ATP

A

Lactate (or Lactic Acid)

132
Q

Which of the following statements is/are correct about purine synthesis?

I. GTP is required for the synthesis of AMP.

II. ATP is required for the synthesis of AMP.

III. GTP is required for the synthesis of GMP.

IV. ATP is required for the synthesis of GMP.

II only

IV only

III only

I only

I and IV

II and IV

A

I and IV

133
Q

In ATP synthase, the interaction of stalk with a beta-subunit in the F1 complex contributes to ATP synthesis by:

Decreasing the free energy for formation of a phosphodiester bond between ADP and Pi

Increasing the free energy for protons to cross the membrane

Allowing the c-ring to rotate with a free energy of ~0

Increasing the free energy of ATP dissociation from the beta subunit

Decreasing the free energy of ATP dissociation from the beta subunit

A

Decreasing the free energy of ATP dissociation from the beta subunit

134
Q

Identify the correct order of the four biochemical mechanisms that are repeated many times to produce Palmitate from Acetyl-CoA and Malonyl-CoA

Dehydration, Reduction, Condensation, Reduction

Reduction, Condensation, Reduction, Dehydration

Condensation, Reduction, Reduction, Dehydration

Reduction, Dehydration, Reduction, Condensation

Condensation, Reduction, Dehydration, Reduction

A

Condensation, Reduction, Dehydration, Reduction

135
Q

Which of the following important intermediates of cholesterol synthesis is missing from this list taken from the four summary steps: Acetate, Squalene, Cholesterol?

CDP-choline

Methyl-malonyl-CoA

Malonyl-CoA

Mevalonate

Phosphatidic Acid

A

Mevalonate

136
Q

The difference between C-3 and C-4 plants is

The number of steps in the Calvin Cycle in one type of plant versus the other type of plant

The number of CO2 molecules required by cells with these pathways to keep the concentration of Oxaloacetate constant in the Kreb’s Cycle

The number of carbons that are in the initial compound into which carbon is fixed

The total number of carbons that are removed as CO2 by one turn of the Calvin Cycle in each plant type

The number of carbons in the final Cycle products of Calvin Cycle for different plants

A

The number of carbons that are in the initial compound into which carbon is fixed

137
Q

Which of the following statements best describes the reactions of the Third Stage of Carbon Assimilation?

Dihydroxyacetone phosphate is used to produce either starch or sucrose

Triose phosphates are converted to pentose phosphates

Triose phosphates are reduced to form glyceraldehyde 3-phosphate

Decarboxylation of pentose phosphates to produce oxaloacetate

Carbon dioxide is incorporated into a pentose

A

Triose phosphates are converted to pentose phosphates

138
Q

In the Urea Cycle, ________ made in the cytosol is passed into the mitochondria, which is converted in the next step to _____________ which is then passed back to the cytosol.

Ornithine, Citrulline

Citrulline, Ornithine

Ornithine, Argininosuccinate

Ornithine, Carbamoyl phosphate

Citrulline, Carbamoyl phosphate

A

Ornithine, Citrulline

139
Q

The strategy of using multiple isozymes to catalyze an early shared step in amino acid synthesis, each of which is subject to a unique set of allosteric effectors is referred to as:

Uncompetitive inhibition

Sequential inhibition

Enzyme multiplicity

Concerted inhibition

Feedback inhibition

A

Enzyme multiplicity

140
Q

What is the final electron acceptor in Oxidative Phosphorylation?

Cytochrome c

Carbon dioxide

Water

Hydrides

Molecular oxygen

A

Molecular oxygen

141
Q

Which process occurs in photosynthesis?

I. Carbon atoms in CO2 become reduced.

II. Oxygen atoms in water become oxidized.

III. NADP is reduced to NADPH by electron transport processes.

III only

II only

None of these processes occur in photosynthesis.

I only

I, II and III

A

I, II and III

142
Q

Precursors for the biosynthesis of the pyrimidine ring system include:

glycine and succinyl-CoA.

glycine, glutamine, CO2, and aspartate.

glutamate, NH3, and CO2.

carbamoyl phosphate and aspartate.

inosine and aspartate.

A

carbamoyl phosphate and aspartate.

143
Q

Flavin mononucleotide

Biotin

Phosphopantethiene

Pyridoxal phosphate

Lipoic Acid

A

Pyridoxal phosphate

144
Q

If a person’s urine contains unusually high concentrations of urea, which one of the following diets has he or she probably been eating recently?

High carbohydrate, very low protein

Very low carbohydrate, very high protein

Very high carbohydrate, no protein, no fat

Very high fat, very low protein

Very very high fat, high carbohydrate, no protein

A

Very low carbohydrate, very high protein

145
Q

Heme groups are prosthetic groups in which Complex?

F1/Fo Particles

Oxygen Evolving Complex

Complex I

Complex III

Phosphate translocase

A

Complex III

146
Q

How many protons must be pumped across the membrane in order to make 1 molecule of ATP? (Consider all processes. Assume, as we did in class, that the c-ring of Fo has 9 subunits).

3

4

2.5

10

6

A

4

147
Q

Cytochrome c is a mobile electron carrier that moves among Complexes of the mitochondrial electron transport chain. Which Complexes does it move between?

IV and the F1/Fo ATPase

I and III

III and IV

II and IV

II and III

A

III and IV

148
Q

Most bacteria can synthesize all twenty amino acids. But certain mutant strains, known as “auxotrophs” are unable to synthesize a particular amino acid, and require the addition of that amino acid to their growth media in order to grow well. A glycine auxotroph would fail to synthesize glycine, as well as the following molecule:

Serine

Cytosine Nucleotides

Guanine nucleotides

Cysteine

3-phosphoglycerate

A

Guanine nucleotides

149
Q

Reactions catalyzed by which of the following proteins do NOT contribute electron carriers to the electron transport chain?

Succinate dehydrogenase

Malate dehydrogenase

Alcohol dehydrogenase

Glucose-6-phosphate dehydrogenase

A

Glucose-6-phosphate dehydrogenase

150
Q

The synthesis of amino acids often involves transamination reactions, resulting in the synthesis of which Kreb’s Cycle intermediate?

Alpha-ketoglutarate

Malate

Oxaloacetate

Fumarate

Citrate

A

Alpha-ketoglutarate

151
Q

Which of the following is true of non-cyclic phosphorylation in photosynthesis?

The same electrons used by the oxygen evolving complex are not used for ADP phosphorylation.

ADP phosphorylated by Cfo/CF1 is transported from chloroplasts and not used by them, so there is no phosphorylation/dephosphorylation cycle

Activated electrons from NADP+ reduction are passed through Plastocyanin to reduce P700+

NADH donates electrons to reduce P680, causing phosphorylation of ADP

Molecular oxygen is evolved and NADP+ is reduced

A

Molecular oxygen is evolved and NADP+ is reduced

152
Q

Which of the following is involved in Photophosphorylation and NOT Oxidative Phosphorylation

Cytochrome c

Cytochrome B6f

Coenzyme Q

Iron-Sulfur Centers (Clusters)

Copper Centers

A

Cytochrome B6f

153
Q

You add carbamoyl phosphate with an isotopically-labelled nitrogen to the cell. Which of the following nucleotides will contain the nitrogen label?

None of these

CTP

ATP

GTP

A

CTP

154
Q

The initial reaction in the REDUCTIVE phase (Stage 2) of the Calvin cycle is the reverse of a particular reaction in another pathway. What is the driving force for this reaction in the Calvin cycle?

This reaction uses Mg2+ and the elevated concentration of Mg2+ during the day helps to drive it forward

This reaction is favorable due to the high concentration of ATP made in the light reactions of photosynthesis.

This reaction is favorable due to the high concentration of NADPH made in the light reactions of photosynthesis.

In the direction it runs in the Calvin cycle, there is a large and negative LaTeX: \DeltaΔ
G’0 so the reaction is naturally favorable.
Submit

A

This reaction is favorable due to the high concentration of ATP made in the light reactions of photosynthesis.

155
Q

In photosynthesis, absorption of light energy in chloroplast “light reactions” ultimately leads to:

absorption of O2 and release of CO2.

absorption of CO2 and release of O2.

hydrolysis of ATP and reduction of NADP+.

use of iron-sulfur proteins.

synthesis of ATP and oxidation of NADPH.

A

absorption of CO2 and release of O2.

156
Q

How many reducing equivalents are transferred to molecular oxygen for the ten protons pumped out of the inner mitochondrial membrane by Complexes I through IV?

10

2

6

1

4

A

2

157
Q

Identify which of the following is not present in chloroplasts but is present in mitochondria

Electron transport system

Porphyrin rings

DNA

Matrix

Iron-Sulfur centers (clusters)

A

Matrix

158
Q

Onto which side of the mitochondrial membrane, or into which space, are protons actively pumped during electron transport?

Into the Cytoplasm

Into the Lumen

Into the Stroma

Into the Lamellae

Into the Intermembrane Space

A

Into the Intermembrane Space

159
Q

There is a defect in Complex III of some mitochondria that prevents protons frombeing pumped to the intermembrane space by this complex. All other complexes apparently function normally. How many total protons are pumped during oxidative phosphorylation in these mutant mitochondria if the initial electrons come from NADH?

10

6

4

8

2

A

6

160
Q

If ornithine labelled with 15N is added to cells actively metabolizing amino acids, which of the following molecules will be rapidly labelled with 15N?

Urea
Arginine
Citrulline

I only

III only

All of these

II and III only

II only

A

II and III only

161
Q

The order of the key intermediates in cholesterol synthesis is:

activated isoprenes, mevalonate, squalene, lanosterol

mevalonate, activated isoprenes, squalene, lanosterol

activated isoprenes, mevalonate, lanosterol, squalene

mevalonate, activated isoprenes, lanosterol, squalene

mevalonate, squalene, activated isoprenes, lanosterol

A

mevalonate, activated isoprenes, squalene, lanosterol

162
Q

What molecule is the ultimate electron donor in Photophosphorylation?

Chlorophyll

NADH

Water

Oxygen

Carbon Dioxide

A

Water

163
Q

Why are Reaction Centers named as such? (That is, why are they called Reaction Centers?

They release an electron, meaning they participate in oxidation-reduction

They split water

They produce molecular oxygen

They produce carbon dioxide

They capture an exciton of light

A

They release an electron, meaning they participate in oxidation-reduction

164
Q

Which of the following statements is TRUE about the following molecule:
In the mitochondria shuttle system, this molecule is generated in the matrix via oxidation of malate

This molecule is transported across the mitochondrial membrane by a shuttle system

This molecule is a direct carbon precursor to alanine, cysteine, and glycine

This molecule can be converted to pyruvate in a single enzymatic step

This molecule is the alpha-keto acid of glutamate

A

In the mitochondria shuttle system, this molecule is generated in the matrix via oxidation of malate

165
Q

The final reaction in synthesizing dNTPs is catalyzed by ribonucleotide reductase. This enzyme will:

Reduce the 2’ OH on an NTP using 2 electrons

Oxidize the 3’ OH on an NTP releasing 2 electrons

Catalyze the hydrolysis of the 2’OH from an NTP.

Oxidize the 3’ OH on an NTP releasing 2 electrons

Reduce the 3’ OH on an NTP using 2 electrons

A

Reduce the 2’ OH on an NTP using 2 electrons

166
Q

The synthesis of Cysteine from Serine requires ___ electrons to reduce sulfate to sulfide.

2

10

4

6

8

A

8

167
Q

Refer to the following diagram of the plant photosystems. Which of the following statements is FALSE?

To synthesize a molecule of NADPH, photons must be absorbed at both P680 and P700

Electron transfer in PSI can contribute to ATP synthesis or NADPH synthesis

Photon absorption decreases the electron affinity of the reaction center

Cytochrome b6f has a higher standard reduction potential than ferridoxin

P700 has a higher electron affinity than P680.

A

P700 has a higher electron affinity than P680.

168
Q

When the ΔG’° of the ATP synthesis reaction is measured on the surface of the ATP synthase enzyme, it is found to be close to zero. This is thought to be due to:

stabilization of ADP relative to ATP by enzyme binding.

a very low energy of activation.

enzyme-induced oxygen exchange.

None of the above

stabilization of ATP relative to ADP by enzyme binding.

A

stabilization of ATP relative to ADP by enzyme binding.

169
Q

The product of the following reaction (indicated with ???) has which of the following uses?
it can be converted into another amino acid in a one-step reaction

All choices are correct.

It can be used to make Arginine

It can be directly fed into the Urea cycle

It can be incorporated in proteins

A

All choices are correct.

170
Q

Which of the following is true regarding Ubiquinone?

It must accept two protons and 4 electrons to go from a fully reduced to a fully oxidized state.

None of the above statements is true regarding Ubiquinone

It is assigned to neither Complex II nor Complex III since its role is to function as a carrier between them

It can accept one electron to become a relatively stable radical

It contains one FAD and one iron-sulfur center

A

It can accept one electron to become a relatively stable radical

171
Q

Which of the following statements is NOT true of the major regulatory point for cholesterol synthesis.

I. It is immediately after reactions which are shared with the formation of ketone bodies.

II. It is at a step where 2 NADPH molecules are consumed.

III. A coenzyme A molecule is released.

IV. It introduces a branch point in a linear molecule.

IV only

All of the choices are true.

II only

III only

I only

A

IV only

172
Q

What vertebrate organ/tissue is responsible for production of large amounts of Ketone Bodies from ketogenic amino acids?

Muscle

Kidney

Liver

Brain

Intestine

A

Liver

173
Q

Eukaryotic cells synthesize which of the following from CDP-diacylglycerol?

Sucrose

Starch

Glycerol

Phospholipids

Cholesterol

A

Phospholipids

174
Q

Conversion of ornithine to citrulline is a step in the synthesis of:

tyrosine.

urea.

pyruvate.

aspartate.

carnitine.

A

urea.

175
Q
A

Biochem (3 decks)

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