-Plasma membrane have several functions such as it separates the contents of the cell from its outside environment and it regulates what enters and exits …show more content…
What makes a plasma membrane a central cellular structure?
3. What makes the plasma membrane semipermeable to substances?
- The plasma membrane is said to be selectively permeable because it allows certain substances to pass through while blocking the passage of others. The actual structure of the plasma membrane allows free passage or restricts movement of substances across the membrane. There are three ways in which the plasma membrane controls the movement of substances, these are the simple diffusion, facilitated diffusion and active transport. 4. How do lipid/steroids substances cross the plasma membrane? What transport mechanisms are involved when lipids cross the plasma membrane?
- Steroids can pass through the plasma membrane independently, even though they are much bigger molecules than water or carbon dioxide. Many steroids are important signaling molecules that are generated in one part of a complex organism and stimulate a reaction in another part of the organism. Simple diffusion is the transport mechanism involved when lipid cross the plasma membrane since lipid diffusion is evidently a passive diffusion process, which means no energy is involved and substances can only move down their concentration gradient. Simple diffusion cannot be controlled by the cell, in the sense of being switched on or