Ch.10

Glutathione peroxidase:

one of the four major enzymatic defenses against oxidative stress. a selenium-containing enzyme key component in an enzymatic system most responsible for controlling cellular peroxide levels catalyzes reduction of substances by GSH reduces peroxide to form water transforms peroxides into alcohols

The cytochromes contain which type of prosthetic group?

Heme

All the following are components of the electron transport chain except

Include: Complex I (NADH dehydrogenase complex) Complex II (succinate dehydrogenase complex) Complex III (cytochrome bc1 complex) cytochrome c Complex IV (cytochrome oxidase)

Examples of antioxidants include all the following except

Include: alpha-tocopherol (vitamin E), ascorbic acid (vitamin C), beta-carotene

________ is a metal cofactor of cytochromes.

Iron

Reducing power generated in the cytoplasm can be transferred into the mitochondrion by which of the following processes?

Malate-aspartate shuttle/ glycerol phosphate shuttle

. Antimycin A inhibits cyt b in complex III. If this inhibitor is added to a suspension of mitochondria which of the following will increase in concentration?

NAD+, flavins, and cyt b reduced (increase in concentration) Cytochromes c1, c, and a oxidized (Neither NADH not FADH2... Both will be saturated because they wouldn't get used.)

Which of the following is the best reducing agent?

NADH usually

Which of the following would not be classified as a ROS?

ROS include: superoxide radical, hydrogen peroxide, hydroxyl radical, singlet oxygen

The principal sources of electrons for the electron transport system is (are) which of the following?

Reduced coenzymes, derived from glycolysis, citric acid cycle, fatty acid oxidation

Which of the following molecules inhibits Complex I of the electron transport chain?

Rotenone and amytal

Which of the following is not a step in the ATP synthesizing process?

Three steps: 1) ADP and Pi bind to L site (rotation converts L conformation → T conformation) 2) ATP is synthesized 3) ATP is released as T conformation converts to O conformation

In the ATP synthase the Fo factor

also known as transmembrane channel for protons, has 3 subunits (a, b2, c10-12). Fo motor converts proton motive force into rotational force of central shaft that drive ATP synthesis.

During the oxidation of NADH there are several steps in which delta E0' is sufficient for ATP synthesis. These occur within

complex I,II,III,IV

In Complex III, electrons are transferred from UQH2 to

cytochrome c (cyt c).

Examples of uncouplers include

dinitrophenol (DNP), FCCP, CCCP.

Glutathione peroxidase requires ____ for full activity.

glutathione reductase

The reaction of Fe+2 with H2O2 results in production of

hydroxyl radical ( OH)

______ are hydrophobic molecules that dissipate ionic gradients.

ionopheres

ROS are generated during

nonenzymatic processes (exposure to UV light and ionizing radiation causes ROS formation)

Nonshivering thermogenesis is regulated by which of the following?

norepinephrine

According to the solid state model of electron transport electron transfer is efficient because

of short diffusion distances for the mobile electron carriers.

A respiratory burst is initiated when NADPH reacts with oxygen to produce which of the following?

oxygen radical

The ultimate electron acceptor of the mitochondrial electron transport system is

oxygen.

The NADPH required for generation of GSH from GSSG is synthesized by the reactions of

pentose phosphate pathway.

Molecules involved in the conversion of oxidized proteins to their functional reduced suylfhydryl form include all the following except

peroxiredoxins, Thioredoxin, Thioredoxin reductase

ATP synthesis and mitochondrial electron transport are coupled by

proton gradient across inner mitochondrial membrane/chemiosmosis.

The return of ___ into mitochondrion is coupled to the formation of ATP.

protons

The statement aerobic organisms use oxygen to generate energy required to maintain metabolic processes yet they risk damage caused by highly reactive oxygen molecules can be referred to as:

reaction oxygen species (ROS)/ paradox of oxygen.

The function of complex III is the transfer of electrons from

reduced coenzyme Q (UQH2) to cytochrome c protein.

The first ROS formed during the reduction of oxygen is

super oxide radical ( O2-)

The primary function of catalase is

to catalyze conversion of peroxide to water and dioxygen

The ultimate waste products of aerobic cellular metabolism of oxygen include

water and CO2.

The energy that is captured by the electron transport system is in the form of

ATP

Which of the following acts as an allosteric inhibitor of complex IV?

ATP

Evidence supporting the charismatic theory includes all the following except:

1) pH drops in a weakly buffered mitochondria suspension when actively respiring 2) Disruption of inner membrane stops respiration 3) Uncouplers and ionophores disrupt proton gradient, inhibiting ATP synthesis

One of the mechanisms by which vitamin C protects membrane is by:

1) preventing lipid per oxidation by reacting with peroxyl radicals formed in cytoplasm before they can reach the membrane 2) enhancing antioxidant activity of vitamin E by regenerating reduced alpha tocopherol from alpha tocopheroxyl radical

The maximum P/O ration of FADH2 is

1.5

How many ATP are generated during oxidation of one NADH?

2.5 / 2.25

The final product of oxidative phosphorylation is ATP

36 molecules

How many protons are required to drive phosphorylation of ADP by the mitochondrial ATP synthase?

4

21. The major sources of NADH that reduce Complex I of the ETC include

???

The control of aerobic respiration by ___ is referred to as respiratory control.

ADP

Which of the following complexes contain copper?

Complex IV cytochrome oxidase

The ETC component that transfers electrons directly to oxygen is

Complex IV, cytochrome oxidase.

Carbon monoxide inhibits which of the following?

Cytochrome oxidase (electron transport)