Diffusion

Definition

Diffusion is the process by which molecules spread from areas of high concentration to areas of low concentration, resulting in an even distribution of substances. This passive movement occurs naturally and is crucial for various biological processes, particularly in the functioning of cells and their interactions with their environment.

5 Must Know Facts For Your Next Test

1. Diffusion does not require energy, making it a type of passive transport vital for cellular function.
2. Small nonpolar molecules, like oxygen and carbon dioxide, can easily diffuse across cell membranes due to their size and chemical properties.
3. The rate of diffusion is influenced by factors such as temperature, size of the molecules, and the medium through which they are diffusing.
4. Cells rely on diffusion to transport essential nutrients and remove waste products efficiently.
5. In a biological context, diffusion plays a key role in processes like gas exchange in the lungs and nutrient absorption in the intestines.

Review Questions

• How does diffusion contribute to maintaining homeostasis in cells?
  • Diffusion helps maintain homeostasis by ensuring that essential substances like nutrients and gases are balanced within the cell. As molecules move from areas of high concentration to low concentration, cells can efficiently take in necessary materials and expel waste products. This dynamic balance allows cells to function optimally, adapting to changes in their internal and external environments.
• Compare and contrast diffusion with facilitated diffusion, highlighting their differences in mechanism and efficiency.
  • Diffusion occurs directly through the cell membrane without assistance, typically involving small or nonpolar molecules. In contrast, facilitated diffusion requires specific transport proteins to help larger or polar molecules cross the membrane. While both processes are passive and rely on concentration gradients, facilitated diffusion is often more efficient for certain substances that cannot easily penetrate the lipid bilayer on their own.
• Evaluate the role of temperature in affecting the rate of diffusion and its implications for cellular processes.
  • Temperature plays a significant role in influencing the rate of diffusion; as temperature increases, so does molecular movement, leading to faster diffusion rates. This has important implications for cellular processes since higher temperatures can enhance nutrient uptake and waste removal. However, excessively high temperatures may also disrupt cellular structures and functions, demonstrating the need for optimal conditions for effective diffusion.

Related terms

Concentration Gradient: The difference in the concentration of a substance across a space, which drives the process of diffusion.

Osmosis:

The specific type of diffusion that refers to the movement of water molecules through a selectively permeable membrane.

Facilitated Diffusion: A process that helps larger or polar molecules diffuse across cell membranes with the assistance of transport proteins.