What are the examples of selectively permeable membrane?
Posted September 20, 2023
Selectively permeable membrane is a type of cellular membrane that allows only select particles and molecules to pass through it but inhibits the entry or exit of other substances.
Examples of selectively permeable membrane include:
Cell Membrane (Plasma Membrane)
The cell membrane surrounds all cells, separating and protecting the interior of the cell from the outside environment. It is made up of a lipid bilayer wherein the phospholipids are arranged in such a way that the hydrophilic phosphate heads of each molecule are exposed to the aqueous external and internal environment while the hydrophobic fatty acid tails lie embedded inside the membrane. This arrangement gives the bilayer its semipermeable nature, which regulates the passage of molecules in and out of the cell. It allows certain molecules like oxygen and glucose to enter while restricting the passage of larger molecules and ions.
Mitochondria are the energy-producing organelles in cells and play a key role in cellular respiration. Mitochondria have inner and outer membranes. The inner mitochondrial membrane is selectively permeable and controls the flow of ions and molecules involved in energy production ensuring that the metabolic rate and internal chemistry of intercellular and extracellular environments remain undisturbed.
Nuclear Membrane (Nuclear Envelope)
The cell’s nucleus is enclosed by a semipermeable double membrane that controls the movement of molecules between the nucleus and the cytoplasm. It selectively permits the passage of specific molecules, such as RNA and proteins.
A neuron enters an excited state in order to transmit an electrochemical signal. It must then eventually return to its resting state before relaying the next signal. This alternating cycle of excitement and relaxation in the neuron is facilitated by a semipermeable synaptic membrane that selectively controls the movement of ions.
Chloroplasts, which are found in plant cells, are responsible for photosynthesis. The thylakoid membranes within chloroplasts are selectively permeable, allowing for the movement of ions and molecules involved in photosynthesis.