For accomplishing the task effectively, they require an optimal concentration of ions, molecules, and proteins. Following are the different biological examples that explain the importance of selectively permeable membranes in order to function more effectively. Mitochondria is one of the essential organelles of the cell.
It is also considered the powerhouse of the cell. It is responsible for cellular respiration and the process is the aid of certain proteins. A selectively permeable membrane performs this task. It brings in proteins without disturbing the internal chemistry and metabolic rate of inter and extracellular environments.
A neuron comes to an excited state while transmitting the electrochemical signal. Before passing the next signal it should be recovered and return to its resting potential. This alternate excitation and relaxation of the neuron are maintained by a selectively permeable membrane by the selective discharge of ions.
The alternate excitation and relaxation also happened in cardiac muscles and heartbeat. A selectively permeable membrane is responsible for maintaining equilibrium among the inter and extracellular environment for keeping the heartbeat normal. It is not easy to visualize the cell membrane through a light microscope. Due to this, the hypothesis about the existence of selectively permeable membrane cell membrane came in the late 19th century, almost years after the cell had been discovered.
At different times, different models had been suggested to explain what is a selectively permeable membrane. The selectively permeable cell membrane was identified in the s but its chemical composition was explained in The structure of the cell membrane makes it flexible which makes it an ideal boundary for growing cells.
Lipids and proteins are identified as the main components in the membrane. James Danielli and Hugh Davson in , proposed the structure of the membrane. This was the first structure that was accepted widely. Danielli and Davson said that the structure of a selectively permeable membrane resembles a sandwich.
They said proteins are like bread and lipids are in the form of filling. With the passage of time and advancement in transmission electron microscopy TEM , a more defined structure was proposed in the s. According to this, the structure consists of a double-layer despite being single.
Singer and Garth L. Nicolson in proposed a new and better model for explaining the structure of the selectively permeable membrane. Although the fluid mosaic model evolved still it explains the structure of selectively permeable membrane in the best way. The fluid mosaic model said that the plasma membranes are selectively permeable; this means that the structure of a selectively permeable membrane is a mosaic of components that includes proteins, phospholipids, carbohydrates, and cholesterol.
Cholesterol or protein molecules are either embedded or present on the entire lipid bilayer. There is variation in the structure of a selectively permeable membrane and other membranes. It has multiple nuclear pore complexes.
The cellular contents are surrounded by a double layer, cell membrane. These cellular structures and cell junctions are elaborated in this tutorial Read More. Generation of resting membrane potential. Skip to content Main Navigation Search. Dictionary Articles Tutorials Biology Forum. Cell Structure A typical eukaryotic cell is comprised of cytoplasm with different organelles, such as nucleus, endoplasmic reticulum, Golgi apparatus, mitochondria, and so on.
How does a cell membrane affect water movement? How does a cell membrane become polarized? How does the lipid bilayer form a barrier to molecules? How does cholesterol affect lipid bilayer? How do lipid bilayers form? How do ions cross the lipid bilayer? How can a molecule be hydrophobic? How do cells regulate ion movement?
0コメント