Animal Cell Practical: Osmosis & Tonicity Flashcards
(12 cards)
What is osmosis?
The movement of water across a semipermeable membrane from a region of lower particle concentration to a region of higher particle concentration.
What is tonicity?
Tonicity describes how a solution affects cell volume, considering both osmotic concentration and membrane permeability.
What is osmotic concentration measured in?
Milliosmoles (mOsm), which account for the number of particles in solution, not just solute concentration.
What is the reflection coefficient?
A value indicating a solute’s permeability across a membrane:
1 = impermeant
0 = freely permeant
What happens to red blood cells in an isotonic solution?
They remain normal in size and shape.
What happens to red blood cells in a hypertonic solution?
They lose water and become crenated (shrunken).
What happens to red blood cells in a hypotonic solution?
hey take in water, swell, and may burst (hemolysis).
Why does water move across the membrane during osmosis?
Due to Brownian motion and electrostatic interactions at aquaporins which drive water toward the side with more solutes.
What are aquaporins?
Protein channels in the cell membrane that facilitate bulk water transport.
Why do some solutions with the same osmotic concentration have different effects on cells?
Because of differences in solute permeability; tonicity depends on both osmotic concentration and reflection coefficient.
What happens when aquaporins are blocked (e.g., with HgCl₂)?
Water movement slows or stops, reducing swelling or bursting even in hypotonic solutions.
What is the role of mercuric chloride (HgCl₂) in Experiment B?
t blocks aquaporins, limiting water transport across the membrane.
