Biochem Ch.14 Online HW

Which of the statement is TRUE for flavoproteins involved in electron transport chain? Flavin nucleotides of flavoproteins can link two-electron and one-electron process. The flavoproteins contains a dominant squalene structure. The complex III and complex IV contains flavoproteins. All the flavoproteins provide the same standard reduction potential on Flavin.

Flavin nucleotides of flavoproteins can link two-electron and one-electron process.

Arrange the following steps or substances by where they appear in the process of glucose metabolism.

Glucose is physically broken apart during glycolysis to form pyruvate. Then pyruvate is converted to acetyl CoA. Acetyl CoA goes through the citric acid cycle, and this cycle produces many NADH and FADH2 molecules. NADH and FADH2 enter the electron transport chain, which oxidizes them and uses the energy to pump protons out of the matrix of the mitochondrion. These protons drive ATP synthase to produce ATP.

How is heme A different from heme?

Heme A has side chain modified by a formyl and isoprenoid group.

Cytochrome c, an essential protein of the electron transport chain, is located in the mitochondria. Please identify its specific location.

Intermembrane space

Which intermediates of citric acid cycle are NAD+ -linked substrates?

Isocitrate Alpha-ketogluterate Malate

What functional unit imparts the lipophilic character to coenzyme Q?

Isoprene

The complete reaction catalyzed by complex I can be summarized as ________.

NADH + Q +5H+ ↔ QH2 + NAD+ + 4H+

Which electron carrier transfers electron to Complex III?

Coenzyme Q

Coenzyme Q carries electrons between which stages of the electron-transport chain? Complex II and Complex III Complex I and Complex III Complex III and Complex IV Complex I and Complex II

Complex II and Complex III Complex I and Complex III

Which two of the above steps would you most expect to serve as key steps for kinetic control?

Between C and D Between B and C

Calculate the standard free energy change for the reaction Pyruvate + CO2 + H+ + 2e- → Malate, given that the standard reduction potential for the reduction of pyruvate to malate is -0.33.

63 kJ

Structure A is _____.

ATP synthase

Which complexes of electron transport chain contain an iron-sulfur cluster?

Complexes I, II and III

What is the role of FMN in complex I?

Converts a two-electron transfer to a one-electron transfer.

Besides iron ion in the heme A of cytochromes a and a3 what other metal ion is available as an electron donor and acceptor?

Copper

The terminal electron acceptor for complex III of the electron transport chain is ________.

Cytochrome c

For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle.

Each glucose produces two pyruvates, each of which is converted into acetyl CoA.

Which complexes in the electron transport chain do NOT contribute to the pumping of protons in to the intermembrane space? I and V III and IV II and V I and II

II and V

What is the total number of ATP molecules that can be produced from the complete oxidation of one glucose molecule?

If you estimate that within the mitochondria 1 NADH produces 2.5 ATP and 1 FADH2 produces 1.5 ATP, then 32 ATP are produce. Some biochemist round up and estimate that 1 NADH produces 3 ATP and 1 FADH2 produces 2 ATP within the mitochondria, thus they obtain 36 ATP produced.

Cristae in mitochondria comprises what part of mitochondria?

Inner membrane

Which of the statement is TRUE for Complex V of the respiratory chain complex? It pumps the electrons in to the intermembrane space. It pumps electron back to matrix and produces ATP. It pumps the electrons in to the matrix of mitochondria. It is involved in the production of ATP from ADP.

It pumps electron back to matrix and produces ATP.

Which of the statement is TRUE for Complex I of the respiratory chain complex? It receives electrons from oxidation of NADH. It transfers the electrons from coenzyme Q to cytochrome c. It receives electrons from oxidation of FADH2. It catalyzes the oxidation of cytochrome c.

It receives electrons from oxidation of NADH.

What is the order for the flow of electrons through the electron transport chain in mitochondria?

NADH succinate coenzyme Q cytochrome c oxygen

During electron transport, energy from _____ is used to pump hydrogen ions into the _____. During

NADH and FADH2 intermembrane space

The number of electrons carried by coenzyme Q at a time during the electron transport chain.

One

What is the terminal electron acceptor in the electron transport chain and ATP synthesis in mitochondria?

Oxygen

The proximate (immediate) source of energy for oxidative phosphorylation is _____.

kinetic energy that is released as hydrogen ions diffuse down their concentration gradient

In cellular respiration, most ATP molecules are produced by _____.

oxidative phosphorylation

Concentration gradients are a form of

potential energy

ATP synthase phosphorylates

ADP

The final electron acceptor of cellular respiration is _____.

Oxygen

The cell uses organelles to sequester reactions and concentrate reactants. Match each stage of cellular respiration with its location in the cell.

->Cytosol: Glycolysis ->Mitochondrial matrix: CAC ->Inner mitochondrial membrane: Oxidative phosphorylation

For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle.

3 NADH + H+ are produced per each acetyl CoA that enters the citric acid cycle.

Label the steps of electron transport leading to oxidative phosphorylation where ATP is synthesized from ADP using the energy stored by the electron-transport chain.

Energy is required to move electrons and protons into the intermembrane space, and this energy is released when the protons move back into the matrix through ATP synthase. This energy is harnessed to phosphorylate ADP, forming ATP.

The iron can gain or lose electron to move from ________ and ________ states.

Fe+2 Fe+3

Rank the following molecules by the number of ATP molecules they produce.

Pyruvate can be oxidized to produce 12.5 ATP molecules. Acetyl CoA can likewise be oxidized to produce 10 ATPmolecules. The electron carriers NADH and FADH2 have enough energy to produce 2.5 and 1 ATP molecules, respectively. GTP carries the same amount of energy as ATP.

The density of cristae is higher in mitochondria of the cell with higher rates of ________.

Respiration

What is the name of Complex II based on its function in electron transport chain?

Succinate-coenzyme Q reductase

Explain this apparent paradox.

The standard reduction potential for FAD is higher than NAD+, making FAD a stronger oxidant than NAD+. Flavin adenine dinucleotide (FAD) is a flavoprotein (or flavin dehydrogenase) cofactor which is tightly bound to the E3component of the pyruvate dehydrogenase complex (PDH complex) known as lipoamide dehydrogenase. FAD accepts a pair of electrons from reduced lipoamide (dihydrolipoamide) to form reduced FADH2. Each flavoprotein provides a different microenvironment resulting in the flavin being conferred a unique redox potential. In lipoamide dehydrogenase, the redox potential of flavin becomes more negative than in other flavin-dependent dehydrogenases. Hence, electrons are able to move from FADH2 to NAD+ under physiological conditions. Additionally, nicotinamide adenine dinucleotide (NAD+) acts as a dissociable substrate for lipoamide dehydrogenase after accepting a pair of electrons from reduced FADH2. Hence, despite having a higher standard reduction potential than NAD+, FADH2 bound to the E3 subunit of PDH complex is oxidized by NAD+.