Biochemistry Exam 3

What is the prosthetic group of dihydrolipoyl transacetylase?

What is the prosthetic group of dihydrolipoyl transacetylase?

lipoamide

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

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

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

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

pyruvate

Acetyl coenzyme A

Oxaloacetate

citrate

Acetyl coenzyme A

The conversion of pyruvate into acetyl CoA consists of three steps

List them

Decarboxylation, oxidation, and transfer of acetyl group to CoA

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

TPP

FAD

Acetyl CoA

Lipoamide

NAD

Lipoamide

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

True

false

False

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

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

Alpha-ketoglutarate dehydrogenase

Isocitrate dehydrogenase

None of the above

Aconitase

Malate dehydrogenase

None of the above

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

Malate dehydrogenase

Alpha-ketoglutarate dehydrogenase

Pyruvate dehydrogenase complex

Isocitrate dehydrogenase

Malate dehydrogenase

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

pyruvate

Citrate

Oxaloacetate

Malate

succinats

Oxaloacetate

In TCA cycle, formation of Lmalate by enzyme fumarase involve

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?

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

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

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.

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

NADH+

FAD

NADH

QH2

FADH2

NADH

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

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

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.

True

False

True

The coenzyme Q is also known as ubiquinone.

Which is NOT correct relating to coenzyme Q

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

Heme bH

HEME BL

HEME A3

FE-SE CLUSTER

HEME

HEME A3

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

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

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]?

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

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

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.

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……..

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?

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

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?

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

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?

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?

A-ketoglutarate

Sycccinyl CoA

Fumarate

Oxaloacetate

Succinante

Succinante

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

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.

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