Lecture on Osmosis and Its Effects

Introduction

• Growing up in West Texas: cold winters, icy roads
• Salt used to prevent ice on roads affects roadside plants
• Salty ocean water during hurricanes can kill plants

Key Concept: Osmosis

• Movement of water through a semi-permeable membrane (e.g., cell membrane)
• Water travels from high to low concentration areas through passive transport
  • No energy required
• Water moves towards areas of higher solute concentration (lower water concentration)

Osmosis Demonstration with U-tube

• U-tube with semi-permeable membrane simulates cell membrane
• Side B with higher solute concentration attracts water from side A
• Water moves to balance solute concentration
• Terminology:
  • Hypertonic: higher solute concentration (e.g., Side B)
  • Hypotonic: lower solute concentration (e.g., Side A)

Osmosis in Real Life Scenarios

IV Fluids and Red Blood Cells

• Pure water in IV is disastrous due to osmosis
• Cells swell and burst when surrounded by pure water
• IV fluids are isotonic to blood plasma to prevent cell damage

Saltwater Fish in Freshwater

• Saltwater fish cells have higher solute concentration than freshwater
• Water moves into fish cells, potentially harmful
• Some fish (e.g., salmon) can adapt to both environments

Plant Water Uptake

• Water moves from saturated soil into hypertonic root hair cells
• Plant cell walls prevent bursting and support structure

Pressure Potential and Water Potential

• Water potential = solute potential + pressure potential
• Solute potential is negative; pressure potential is positive
• Example: Potato cores in water lab
  • Water enters potato cells, increasing turgor pressure

Conclusion

• Osmosis is crucial for water movement in living organisms
• Important for plant structure and growth
• Stay curious about how osmosis affects life processes