Selectively permeable

Definition

Selectively permeable refers to the property of a cell membrane that allows certain molecules or ions to pass through it by means of active or passive transport. This selectivity is essential for cellular homeostasis and function.

5 Must Know Facts For Your Next Test

1. Selectively permeable membranes regulate the entry and exit of substances based on size, charge, and solubility.
2. Passive transport across selectively permeable membranes includes diffusion, facilitated diffusion, and osmosis.
3. The phospholipid bilayer with embedded proteins is a key structural component of selectively permeable membranes.
4. Selective permeability is crucial for maintaining the cell's internal environment distinct from its external surroundings.
5. Transport proteins such as channels and carriers play significant roles in selective permeability.

Review Questions

• What are the primary mechanisms by which molecules move across a selectively permeable membrane without energy input?
• How does the structure of the phospholipid bilayer contribute to selective permeability?
• Why is selective permeability important for cellular function and homeostasis?

Related terms

Diffusion: The movement of molecules from an area of higher concentration to an area of lower concentration without energy input.

Osmosis: The diffusion of water through a selectively permeable membrane from an area of low solute concentration to high solute concentration.

Transport Proteins: Proteins that assist in the movement of substances across a cell membrane, including channels and carriers.