Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 37m
3. Water1h 26m
4. Biomolecules2h 23m
5. Cell Components2h 26m
6. The Membrane2h 31m
7. Energy and Metabolism2h 0m
8. Respiration2h 40m
9. Photosynthesis2h 49m
10. Cell Signaling59m
11. Cell Division2h 47m
12. Meiosis2h 0m
13. Mendelian Genetics4h 44m
14. DNA Synthesis2h 27m
15. Gene Expression3h 6m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 53m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport1h 2m
- Water Potential
  1h 2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 49m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

8. Respiration

Electron Transport Chain

General Biology

8. Respiration

Electron Transport Chain

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3:20 minutes

Problem 8

Textbook Question

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.

Verified step by step guidance

Identify the role of electron transport chains in cellular respiration. Electron transport chains are a series of complexes that transfer electrons from electron donors to electron acceptors via redox reactions, and couple this electron transfer with the transfer of protons (H+ ions) across a membrane. This process creates an electrochemical proton gradient that drives the synthesis of ATP, which is the main energy currency of the cell.

Understand the function of the drug used in the experiment. The drug poisons the enzymes involved in the electron transport chains, effectively inhibiting the process of electron transfer and the subsequent production of ATP.

Relate the inhibition of the electron transport chain to the production of magnetite. Magnetite production in bacteria often involves the reduction of iron, a process that can be linked to the electron transport chain activity. If the electron transport chain is inhibited, the bacteria may not be able to reduce iron to form magnetite.

Analyze the experimental results. In the presence of the drug, no magnetite was produced, suggesting that the normal function of the electron transport chain is crucial for the production of magnetite in these bacteria.

Conclude whether the results support or undermine the hypothesis. Since the inhibition of the electron transport chain (a key component of cellular respiration) stops the production of magnetite, this supports the hypothesis that the bacteria perform cellular respiration, using the electron transport chain to drive processes such as magnetite production.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Cellular Respiration

Cellular respiration is a metabolic process in which cells convert nutrients into energy, primarily in the form of ATP, while producing waste products. This process typically involves glycolysis, the Krebs cycle, and the electron transport chain. In bacteria, this can occur anaerobically or aerobically, depending on the organism and environmental conditions.

Electron Transport Chain (ETC)

The electron transport chain is a series of protein complexes located in the inner mitochondrial membrane (or plasma membrane in bacteria) that facilitate the transfer of electrons derived from nutrients. This process generates a proton gradient that drives ATP synthesis. Inhibition of the ETC can severely disrupt cellular respiration, leading to reduced energy production and metabolic byproducts.

Magnetite Production

Magnetite is a magnetic iron oxide produced by certain bacteria as a byproduct of their metabolic processes, often linked to their respiratory activities. The production of magnetite can indicate the presence of specific metabolic pathways, including those involved in electron transport. If magnetite production ceases when the ETC is inhibited, it suggests that the bacteria rely on cellular respiration for its synthesis.

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Related Practice

Textbook Question

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.

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Textbook Question

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.

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Textbook Question

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

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Textbook Question

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.

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.

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Textbook Question

Explain the relationship between electron transport and oxidative phosphorylation. How do uncoupling proteins 'uncouple' this relationship in brown adipose tissue?

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Textbook Question

Explain the relationship between electron transport and oxidative phosphorylation. How do uncoupling proteins 'uncouple' this relationship in brown adipose tissue?

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Textbook Question

Cyanide (C ≡ N⁻) blocks complex IV of the electron transport chain. Suggest a hypothesis for what happens to the ETC when complex IV stops working. Your hypothesis should explain why cyanide poisoning in humans is fatal.

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