How selectivity of the cell membrane is achieved

Each receptor protein can only recognize and accept one or a few substances. Phosphorus and potassium, for example, are transported by different proteins. (Potassium and sodium are the same protein!)

The selective delivery of cell membrane receptor proteins is due to the notch at the tail of the long chain of the protein, which can only bind to one or a few specific substances due to the nature of the entire protein molecule. There is not just one, but many receptor proteins on the cell membrane; There are many kinds of substances that can be combined. This determines the selective permeability of the cell membrane and the diversity and effectiveness of its permeable substances, ensuring that all the nutrients required by the cell can be accurately and smoothly reached.

The waste products produced by cell metabolism are water and carbon dioxide, which are both small molecules that can enter and exit the cell membrane at will, just like oxygen. They all diffuse from high to low concentrations. Nucleic acids and other substances are macromolecular substances that cannot pass through the cell membrane at will.

Most substances need to be transported by carriers through the cell membrane, and a carrier can only transport one substance, so whether the substance can enter the cell depends on whether there is a corresponding carrier on the membrane, the key is the protein on the membrane, the protein type is different, the transported substance is different, and it has a selective effect.

There are two types: penetration and active transport. Osmosis is achieved by the difference in the concentration of the liquid inside and outside the cell membrane; Active transport is achieved by selective active transport of a protein on the cell membrane.

It is determined by the type and number of carriers on the membrane, if it is not needed, there is no such carrier, and if it is needed, the number of corresponding vectors is also very small....

on the cell membrane. The following three points are decisive in the choice of permeability:

1. Specific transporters with different structures and functions in cell membranes (including carrier proteins.

channel proteins), which differ in type, number, and activity on the plasma membrane of different cells.

2. The phospholipid bilayer of the cell membrane itself.

hydrophobicity.

Features. 3. Cell viability.

Selective permeability means that the membrane can only allow some substances (e.g., glucose, carbon dioxide.

etc.), the property of not allowing other substances (such as proteins) to pass through. Selective permeability is a type of semi-permeability, and only bioactive membranes have selective permeability.

Cell membranes and other biofilms are selectively permeable membranes

So the answer is: biofilm.

The selective permeability of the cell membrane is related to the type of molecule that passes through. The smaller the molecule and the more hydrophobic or non-polar it is, the easier it is to pass through the membrane, such as; O2, CO2, N2, benzene, uncharged polar small molecules can also quickly diffuse through the membrane, such as: H2O and glycerol, for some uncharged polar macromolecules (such as glucose, sucrose) and some ions (such as H+, Na+, HCO3-), impermeable.

1.Specific transporters (including carrier proteins, channel proteins) with different structures and functions in the cell membrane, and they differ in type, quantity, and activity on the plasma membrane of different cells2The hydrophobic characteristics of the phospholipid bilayer of the cell membrane itself.

3.Vitality of cells. The above aspects have a direct role in determining the selection and permeability of cell membranes.

The cell membrane isolates each cell from its surroundings, maintaining a relatively stable environment inside the cell. At the same time, the cell membrane also has important functions such as material exchange, cell recognition, secretion, excretion, and immunity.

The ways in which substances move in and out of the cell include free diffusion (transport from the side with a high concentration of a substance to a side with a low concentration without consuming energy and carriers), active transport (generally from the side with a low concentration of substances to the side with a high concentration of energy, which requires the consumption of energy and carriers), and endocytosis and efflux (macromolecules and particulate matter).

In the process of active transport, due to the different number of carriers of different substances on the cell membrane, it is difficult to beat the different quantity, speed and difficulty of the same substance entering and exiting the cell, which reflects the functional characteristics of the cell membrane - selective permeability.

The type and number of proteins on the cell membrane determine the selective permeability of the cell membrane.

Cell fluidity: it is cell fusion, cell secretion or phagocytosis selective permeability: cell absorption of mineral ions.

A thin film on the surface of a cell. It is sometimes referred to as the extracellular membrane or protoplasmic membrane. The chemical composition of cell membranes is basically the same and is mainly composed of lipids, proteins, and sugars.

Each ingredient contains approximately 10% respectively. Among them, the main components of lipids are phospholipids and cholesterol. In addition, cell membranes contain small amounts of water, inorganic salts, and metal ions.

Related to carrier proteins!! It is related to the type and quantity!! The type determines the substance that passes through, and the quantity determines the amount of the substance that passes through. When the cell membrane is inactivated, it will be fully permeable.

It mainly depends on the glycoprotein on the membrane. There are sugar side chains on glycoproteins, and after the sugar side chains are decomposed, they will lose their selective permeability, and the selective permeability of the cell membrane does not mean that all substances cannot pass through. The component of the cell membrane is the phospholipid bilayer.

1. Specific transporters (including carrier proteins and channel proteins) with different structures and functions in the cell membrane, which have different types, quantities and activities on the plasma membrane of different cells.

2. The hydrophobic characteristics of the phospholipid bilayer of the cell membrane itself.

3. Cell viability. The above aspects have a direct role in determining the selection and permeability of cell membranes.