Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

2. Cell Chemistry & Cell Components

Simple and Facilitated Diffusion

Anatomy & Physiology

2. Cell Chemistry & Cell Components

Simple and Facilitated Diffusion

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2:36 minutes

Problem 14

Textbook Question

SCIENTIFIC THINKING Mercury is known to inhibit the permeability of water channels. To help establish that the protein isolated by Agre's group was a water channel, the researchers incubated groups of RNA-injected oocytes (which thus made aquaporin proteins) in four different solutions: plain buffer, low concentration and high concentration of a mercury chloride (HgCl2) solution, and low concentration of a mercury solution followed by an agent (ME) known to reverse the effects of mercury. The water permeability of the cells was determined by the rate of their osmotic swelling. Interpret the results of this experiment, which are presented in the graph below. Control oocytes not injected with aquaporin RNA were also incubated with buffer and the two concentrations of mercury. Predict what the results of these treatments would be

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Observe the graph which shows water permeability (rate of osmotic swelling) for different treatments of oocytes.

Note that oocytes in buffer have the highest water permeability, indicating normal aquaporin function.

Oocytes in low HgCl2 show reduced water permeability, suggesting that mercury inhibits aquaporin function.

Oocytes in high HgCl2 have even lower water permeability, reinforcing the inhibitory effect of mercury on aquaporins.

Oocytes in low HgCl2 and ME show restored water permeability, indicating that ME reverses mercury's inhibitory effect on aquaporins.

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Key Concepts

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

Aquaporins

Aquaporins are specialized membrane proteins that facilitate the transport of water across cell membranes. They play a crucial role in regulating water permeability in various tissues. In this experiment, the presence of aquaporins in oocytes allows researchers to measure how different conditions affect water movement, providing insights into the function of these proteins.

Mercury Chloride (HgCl2) as an Inhibitor

Mercury chloride (HgCl2) is known to inhibit the function of aquaporins by binding to the proteins and altering their structure, thus reducing water permeability. In the experiment, varying concentrations of HgCl2 were used to assess its impact on the osmotic swelling of oocytes, helping to establish a link between aquaporin activity and water transport.

Osmotic Swelling

Osmotic swelling refers to the increase in cell volume due to the influx of water when cells are placed in a hypotonic solution. This phenomenon is used in the experiment to measure water permeability, as the rate of swelling indicates how effectively water can enter the oocytes. The results help to interpret the effects of aquaporins and inhibitors like HgCl2 on cellular water transport.