8. Respiration

Electron Transport Chain

ELECTRON TRANSPORT CHAIN ANIMATION - Biochemistry High-yield Usmle step 1

The poison cyanide binds to an electron carrier within the electron transport chain and blocks the movement of electrons. When this happens, glycolysis and the citric acid cycle soon grind to a halt as well. Why do you think these other two stages of cellular respiration stop? (Explain your answer.)
a. They run out of ATP.
b. Unused O2 interferes with cellular respiration.
c. They run out of NAD+ and FAD.
d. Electrons are no longer available.

The breakdown of glucose into six carbon dioxide molecules.

The breakdown of NADH and FADH2 to carbon dioxide.

Harnessing energy from high-energy electrons derived from glycolysis, pyruvate oxidation, and the Krebs cycle.

Which of the following events takes place in the electron transport chain?a) The breakdown of glucose into six carbon dioxide molecules.b) The breakdown of NADH and FADH2 to carbon dioxide.c) Harnessing energy from high-energy electrons derived from glycolysis, pyruvate oxidation, and the Krebs cycle.d) Substrate-level phosphorylation.

Suppose that you’ve been hired by a firm interested in using bacteria to clean up organic solvents found in toxic waste dumps. Your new employer is particularly interested in finding cells that are capable of breaking a molecule called benzene into less-toxic compounds. Where would you go to look for bacteria that can metabolize benzene as an energy or carbon source? How would you design an enrichment culture capable of isolating benzene-metabolizing species?

The researchers who observed that magnetite was produced by bacterial cultures from the deep subsurface carried out a follow-up experiment. These biologists treated some of the cultures with a drug that poisons the enzymes involved in electron transport chains. In cultures where the drug was present, no more magnetite was produced. Does this result support or undermine their hypothesis that the bacteria in the cultures perform cellular respiration? Explain your reasoning.

Remembering the ETC

The electron transport chain                   .
a. is located in the matrix of the mitochondrion;
b. has the electronegative carbon dioxide at its base;
c. is a series of nucleotides located in the inner mitochondrial membrane;
d. is a series of enzymes located in the intermembrane space;
e. moves electrons from protein to protein and moves protons from the matrix into the intermembrane space

Electron transport chain

In mitochondria, exergonic redox reactions
a. are the source of energy driving prokaryotic ATP synthesis.
b. provide the energy that establishes the proton gradient.
c. reduce carbon atoms to carbon dioxide.
d. are coupled via phosphorylated intermediates to endergonic processes

Cellular Respiration Part 3: The Electron Transport Chain and Oxidative Phosphorylation

Reducing NAD+ to NADH in glycolysis and the citric acid cycle

No. Electrons from glucose are used to reduce NAD+, but is this the only correct answer?

Producing a proton gradient for ATP synthesis in the mitochondria

No. Electrons from glucose are used to produce a proton gradient for ATP synthesis, but is this the only correct answer?

Driving substrate-level phosphorylation in glycolysis

No. Electrons from glucose are not involved in substrate-level phosphorylation.

The second and third answers are correct.

No. At least one of these answers is incorrect.

Electrons derived from the oxidation of glucose are involved in many different processes in cellular respiration.

Most of the electrons removed from glucose by cellular respiration are used for which of the following processes?

Electrons are pumped across a membrane by active transport.

No. Electrons are not transported in this manner.

Acetyl CoA is fully oxidized to CO2.

No. This occurs in the citric acid cycle.

Hydrogen atoms are added to CO2 to make an energy-rich compound.

No. This represents the production of organic compounds; their oxidation occurs in the process of cellular respiration.

Glucose is broken down to a three-carbon compound in preparation for the citric acid cycle.

Electrons are passed from one carrier to another, releasing a little energy at each step.

The name "electron transport chain" pretty much gives you the answer to the question.

Which of the following best describes the electron transport chain?

Cyanide binds to at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most of the cyanide will be found within the
a. mitochondria.
b. ribosomes.
c. peroxisomes.
d. lysosomes.

The Electron Transport Chain Explained (Aerobic Respiration)

A high level of NADH is present in the cell.

No. If electron transport is inhibited, it is true that NADH levels in the cell rise, but this does not in itself inhibit glycolysis or the citric acid cycle.

The uptake of oxygen stops because electron transport was inhibited.

No. This is a true statement, but it does not explain why glycolysis and the citric acid cycle stop.

Electrons are no longer available from the electron transport chain to power glycolysis and the citric acid cycle.

No. Electrons from the electron transport chain are used to reduce oxygen; they do not participate in glycolysis or the citric acid cycle.

No. In fact, when electron transport is inhibited, the cell's supply of ATP is hydrolyzed rapidly to ADP and phosphate.

NAD+ and FAD are not available for glycolysis and the citric acid cycle to continue.

How is the electron transport chain coupled to glycolysis and the citric acid cycle?

When a poison such as cyanide blocks the electron transport chain, glycolysis and the citric acid cycle also eventually stop working. Which of the following is the best explanation for this?

Animation: Electron Transport

Electron Transport Chain (Music Video)

In the electron transport chain, the final electron acceptor is:a) H2O.b) CO2.c) H2O.d) O2.e) NAD+.

Animation: Electron Transport Chain: Factors Affecting ATP Yield

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?
a. The pH of the matrix increases.
b. ATP synthase pumps protons by active transport.
c. The electrons gain free energy.
d. NAD+ is oxidized.

Cellular Respiration 5 - Oxidative Phosphorylation

No. This is the location of the citric acid cycle.

the intermembrane space of the mitochondrion

No. One of the listed locations is correct.

Think about what is required to form a proton gradient.

In eukaryotic cells, the components of the electron transport chain are located in or on __________.

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1. Introduction to Biology

2. Chemistry

3. Water

4. Biomolecules

5. Cell Components

6. The Membrane

7. Energy and Metabolism

9. Photosynthesis

10. Cell Signaling

11. Cell Division

12. Meiosis

13. Mendelian Genetics

14. DNA Synthesis

15. Gene Expression

16. Regulation of Expression

17. Viruses

18. Biotechnology

19. Genomics

20. Development

21. Evolution by Natural Selection

22. Evolution of Populations

23. Speciation

24. History of Life on Earth

25. Phylogeny

26. Prokaryotes

27. Protists

28. Plants

29. Fungi

30. Overview of Animals

31. Invertebrates

32. Vertebrates