Biochemistry Exam 3

What is the prosthetic group of dihydrolipoyl transacetylase?

lipoamide

In a net chemical reaction the TCA cycle, what is the missing stoichiometry?

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**2 carbon-dioxide**

**4 carbon dioxide**

**Pyruvate**

**6 carbon dioxide**

**Carbon dioxide**

4 carbon dioxide

In the TCA cycle, which of the following enzymatic step is linked to the formation of NADH

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**Fumarase**

**Succinate dehydrogenase**

**Isocitrate dehydrogenase**

**Aconitase**

**Citrate synthase**

Isocitrate dehydrogenase 

True or Falce

The citric acid cycle is the final common pathway for the oxidation of fuel molecules

True

The "only substrate-level phosphorylation" enzymatic step in the TCA cycle forms the following the product

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**Fumarate**

**L-malate**

**Alpha-ketoglutarate**

**succinyl CoA Synthase**

Succinate

succinate

In TCA, aconitase catalysis involves rapid dehydration followed by a quick hydration step

True

False

True

Most fuel molecules enter the TCA cycle as

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**pyruvate**

**Acetyl coenzyme A**

**Oxaloacetate**

**citrate**

Acetyl coenzyme A

The conversion of pyruvate into acetyl CoA consists of three steps

List them

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Decarboxylation, oxidation, and transfer of acetyl group to CoA

The pyruvate dehydrogenase complex cannot complete another catalytic cycle until the dihydrolipoamide is oxidized to…

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TPP

**FAD**

**Acetyl CoA**

**Lipoamide**

**NAD**

Lipoamide

In bacteria, the TCA cycle could be regulated by inhibition at the aconitase enzymatic step

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True

false

False

The following TCA cycle enzyme involved rapid dehydration followed by quick/rapid hydration step

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**Fumarase**

**Succinate dehydrogenase**

**Alpha-ketoglutarate dehydrogenase**

**Isocitrate dehydrogenase**

**Aconitase**

Aconitase

The following enzyme can inhibit the TCA cycle only in bacteria but not in other eukaryotes

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**Alpha-ketoglutarate dehydrogenase**

**Isocitrate dehydrogenase**

**None of the above**

**Aconitase**

**Malate dehydrogenase**

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None of the above

Which of the following TCA enzymes is not linked to the decarboxylation and oxidation processes?

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**Malate dehydrogenase**

**Alpha-ketoglutarate dehydrogenase**

**Pyruvate dehydrogenase complex**

**Isocitrate dehydrogenase**

Malate dehydrogenase

Following the TCA cycle biomolecule is closely linked to "The gluconeogenesis pathway.

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**pyruvate**

**Citrate**

**Oxaloacetate**

**Malate**

**succinats**

Oxaloacetate

In TCA cycle, formation of Lmalate by enzyme fumarase involve

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**Hydration**

**Oxidation reduction**

**Reduction**

Oxidation

**Dehydration**

Hydration

Participation of the three enzymes of the pyruvate dehydrogenase complex and five coenzymes is required for acetyl CoA formation. What are the 5 coenzymes required for this complex?

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\

FAD

NAD+

Coenzyme A

ATP

lipoamide

The Citric Acid cycle (Krebs or TCA cycle ) takes place in mitochondrial Inner membrane space Essentially in TCA cycle the Electrons removed form acetyl CoA to from citrate and FADH2

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True

False

False

**In TCA, isocitrate dehydrogenase enzyme involves rapid dehydration followed by a quick hydration step**

**True**

**False**

False

This allosteric enzyme is the first control point fo the TCA cycle

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**Citrate synthase**

**Malate dehydrogenase**

**fumarase**

**Alpha ketoglutarate dehydrogenase**

**Pyruvate dehydrogenase complex**

**Isocitrate dehydrogenase**

Isocitrate dehydrogenase

Following TCA cycle biomolecule is closely linked to "Pyrimidine" biosynthetic pathway.

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**glutamate from a-ketoglutarate**

**glutamate from succinate CoA** 

**Aspartate from oxaloacetate** 

**Asparate from citrate**

**Asparate from glutamate**

Aspartate from oxaloacetate 

in glycerol 3 phosphate shuttle electrons from ........can enter the Mitrochondrial electron transport chain by being used to reduce dihydroxyacetone phosphate to glycerol 3 phosphate

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NADH+

FAD 

NADH 

QH2

FADH2

NADH

During "Malate -Aspartate Shuttle ", in cytoplasm , aspartate is deaminated to form glutamate and the cycle is restarted

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**True**

**False**

False aspartate makes oxaloacetate by aminating alphaketoglutarate

in the Chemiosmotic hypothesis model, the transfer of electrons through the respiratory chain leads to the pumping of electrons from cytoplasmic side of the inner mitochondrial membrane to the matrix

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**True**

**false**

false it pumps electrons from the matrix to the cytoplasmic side to create the gradient that ATP synthase uses to creat ATP

ATP synthase is composed of a proton conducting unit and catalytic units. The F1 subunit consists of five types of polypeptide chains are?

alpha3, beta3, Gamma, Delta and epsilon

ADP enters the mitochondrial matrix only if ATP exits, and vice versa.

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True

False

True

The coenzyme Q is also known as ubiquinone.

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Which is NOT correct relating to coenzyme Q

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**ubiquinone is a hydrophilic quinone**

**ubiquinone is a hydrophobic quinone**

**Fully oxidized state (Q), coenzyme Q has 2 keto groups**

**Quinones can exist in three oxidation states**

**Scmquonine penetrates ubiquinol (QH3)**

**the fully reduced form of coenzyme o**

ubiquinone is a hydrophilic quinone

Cyanide reacts with the ferric form ....... whereas carbon monoxide inhibits the ferrous form

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**Heme bH**

**HEME BL**

**HEME A3**

**FE-SE CLUSTER**

**HEME**

HEME A3

Most Electron Transport Chain \[ETC\] complex contains Fe-cluster, except this one

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NADHQ oxidoreductase

Q-cytochrome c oxidoreductase 

Cytochrome c reductase 

Succinate Q reductase

Succinate Q reductase (Complex ll)

when second electron and proton to the semiquinone generate ubiquinol ( QH2) the..... From the coenzyme Q which holds its protons more tightly

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**Both oxidized and reduced**

**Fully oxidized**

**Partially reduced**

**Partially oxidized**

**Fully reduced**

fully reduced

Which of the following ETC complex does not involve coenzyme Q in the membrane core \[Reflecting oxidant or reductant role\]?

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**Only ETC I**

**Only ETC II**

**Only ETC Iii**

**all Only ETC I,ii and III**

**Only ETC IV**

Only ETC Il (succinate Q dehydrogenase)

Cytochrome c oxidase (complex IV) catalyzes the ……. of molecular oxygen to water

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**Oxidation**

**First oxidation then reduction**

**Reduction**

**Reduction of coQ**

reduction

In oxidation-reduction reactions, the donor of electrons in model case x is called the reducing agent, whereas the acceptor of electrons H+ here is called the

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**Oxidant**

**Partially reductant**

**Both as redox**

**Reductant**

**Partially oxidant**

Oxidant

A......potential difference between NADH and molecular oxygen drives electron transport through the chain and favors the formation of a proton gradient.

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1\.14 mV

0\.82V

0\.32V

1\.14 

1\.14V

1\.14V

The regulation of the rate of oxidative phosphorylation by the ..... level is called …. or……..

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**FADH2**

**ADP**

**NADH**

**Cytochrome C**

**ATP**

ADP, respiratory control or acceptor control

FADH2 enters the electron transport chain at the second protein complex of the chain. FADH2 does not leave the complex; rather, its electrons are transferred to Fe-S centers and then finally to Q to form QH2.

True

False

True

Which molecule mediates the electroneutral exchange of H2PO4- for ADP in concert with the ATP\* ADP translocase?

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**hydroxide (OH-)**

**pyruvate,**

**phosphoric acid (H3PO4)**

**ATP**

**ADP**

hydroxide (OH-)

In the heart and liver, electrons from ....... are brought into mitochondria by the malate- aspartate shuttle , which is mediated by two membrane carriers and four enzymes

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**Mitochondrial matrix NADH**

**Mitochondrial matrix NAD+**

**Mitochondrial matrix FADH2**

**Cytoplasmic NAD+** 

**Cytoplasmic NADH**

Cytoplasmic NADH

The electrons of NADH enter the chain at NADH- Q oxidoreductase. which is not true for this complex ETC 1?

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**None of them ( all are correct statements)**

**It is the largest ETC complex**

**It has 46 subunits**

None of them ( all are correct statements)

(46 subunits, M.W.>900 kD, FMN pros group, Largest\*)

mitochondria have two membrane systems and outer membrane in an extensive high folded inner membrane the outer membrane is folded into a series of external ridges called cristae

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True

False

False

according to the chemiosmotic hypothesis which location will have basic pH

( higher than neutral such as 9.5 or so) after the pumping process?

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5 matrix

What is the net potential of the reduction of NADH?

0\.32V

name the intermediate shown in circle during the TCA cycle

Oxalosuccinate, intermediate between isocitrate(left) and alpha-ketoglutarate(right)

among the following which one is not a product after the end of the oxidation step in the TCA Cycle?

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A-ketoglutarate

Sycccinyl CoA

Fumarate

Oxaloacetate

Succinante

Succinante

Oligomycin and dicyclohexylcarbodimide (DCCD) prevent the influx of protons through .....

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**NADH Q Oxidoreductase**

**Q-cytochrome c oxidoreductase**

**Cytochrome c oxidase**

**Sussinate Q reductase**

**ATP synthase**

ATP synthase

This enzyme converts pyruvate into oxaloacetate by oxidizing ATP in gluconeogenesis

pyruvate carboxylase

The pyruvate complex cannot complete another catalytic cycle until dihydrolipoamide is oxidized to ……... Afterward, it is regenerated by dihydrolipoyl dehydrogenase (E3) when it is oxidized to its original form.

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lipoamide

based on the electron flow of the respiratory chain and the given picture competent, name the related ETC (electron transport complex) enzyme

NADH Q oxidoreductase (complex 1)

name the intermediate shown in circle during the TCA cycle

Citryl CoA is the intermediate. Oxaloacetate reacts with acetyl coats to make citric coA before producing citrate as the product

in the heart And liver electrons from cytoplasmic NADH are brought into mitochondria by the Malate aspirate shuttle in the cytoplasm the aspirate is then deaminated to form ..... and the cycle is restarted

oxaloacetate