<<–2/”>a href=”https://exam.pscnotes.com/5653-2/”>p>diffusion and facilitated diffusion.
Introduction
Cellular membranes are like gatekeepers, selectively controlling what enters and exits the cell. This movement of substances is essential for nutrient uptake, waste removal, and maintaining a balanced cellular Environment. Two fundamental processes facilitating this movement are diffusion and facilitated diffusion. While both involve the transport of Molecules across the membrane, they differ in their mechanisms and the types of molecules they transport.
Key Differences: Diffusion vs. Facilitated Diffusion
| Feature | Diffusion | Facilitated Diffusion |
|---|---|---|
| Definition | The passive movement of molecules from a region of high concentration to low concentration. | The passive movement of molecules across a cell membrane with the help of specific transport proteins. |
| Energy Requirement | Does not require energy (passive transport) | Does not require energy (passive transport) |
| Molecule Type | Small, non-polar, or lipid-soluble molecules (e.g., Oxygen, carbon dioxide) | Large, polar, or charged molecules (e.g., glucose, ions) |
| Transport Proteins | Not involved | Involved (carrier proteins or channel proteins) |
| Specificity | Non-specific (any molecule can diffuse if it fits through the membrane) | Highly specific (transport proteins bind to specific molecules) |
| Rate of Transport | Relatively slow | Relatively faster than simple diffusion |
| Saturation | Does not saturate (rate increases with concentration) | Saturates (rate reaches a maximum when all transport proteins are occupied) |
| Examples | Oxygen and carbon dioxide exchange in lungs, dye spreading in water | Glucose uptake in cells, ion movement across nerve cell membranes |
Advantages and Disadvantages
| Process | Advantages | Disadvantages |
|---|---|---|
| Diffusion | Simple, does not require energy, allows movement of essential small molecules. | Limited to small, non-polar molecules; slow rate; cannot move against gradient. |
| Facilitated Diffusion | Allows transport of larger, essential molecules; faster than simple diffusion. | Limited by the number of transport proteins; cannot move against gradient. |
Similarities
Both diffusion and facilitated diffusion:
- Are passive transport processes, meaning they do not require the cell to expend energy.
- Move molecules down their concentration gradient (from high to low concentration).
- Are essential for cell survival and function.
FAQs on Diffusion and Facilitated Diffusion
1. What is the main difference between diffusion and facilitated diffusion?
The main difference is that facilitated diffusion requires the help of specific transport proteins, while diffusion does not.
2. Why is facilitated diffusion important for cells?
Facilitated diffusion allows cells to take up essential molecules that are too large or polar to diffuse through the membrane on their own.
3. Can diffusion and facilitated diffusion occur in the same cell?
Yes, both processes can occur simultaneously in the same cell, allowing for the efficient transport of different types of molecules.
4. What factors can affect the rate of diffusion and facilitated diffusion?
Factors affecting the rate include:
- Temperature
- Concentration gradient
- Size of molecules
- Availability of transport proteins (for facilitated diffusion)
5. Can facilitated diffusion move molecules against their concentration gradient?
No, facilitated diffusion, like diffusion, can only move molecules down their concentration gradient. To move molecules against the gradient, the cell must use active transport, which requires energy.
Let me know if you’d like more details on any of these aspects!