What describes the property of selective permeability?

Definition
noun
A feature and a function of the plasma membrane that is essential to maintain homeostasis by regulating the passage of some substances while preventing others from entering the cell
Supplement
Selective permeability refers to the one of the distinctive characteristics of the plasma membrane. The plasma membrane is the membrane that contains the cytoplasm. In the animal cell, it is the outermost covering. In a plant cell, the plasma membrane is found beneath the cell wall. The plasma membrane is capable of being selectively permeable because of its structure. It is composed of a bilayer of phospholipids interspersed with proteins. The phospholipid part of the plasma membrane renders the latter hydrophobic and therefore polar molecules would not be able to easily pass through this layer. The proteins embedded on the plasma membrane act as transporters or channels for certain molecules (e.g. ions). Thus, the composition and structure of the plasma membrane makes the latter semipermeable, i.e. selective to the entry of certain molecules and substances. This means that not all substance would be able to gain entry or exit through the cell. The selective permeability of the plasma membrane helps the latter to carry out an important function of controlling or regulating the passing through of substances between the external environment and the cytoplasm.
See also:

Table of Contents Show

What are the properties of a selectively permeable membrane?
What is an example of selective permeability?
What is the definition of selective permeability quizlet?

fluid mosaic model
plasma membrane

Last updated on June 24th, 2021

In cell biology, selective permeability is the property of a living cell membrane that allows the cell to control which molecules can pass through the membrane, moving into or out of the cell. In order to understand this property, it helps to be aware that there are three different methods by which molecules can move into or out of cells: passive transport, active transport, and transport by the use of vesicles.

In passive transport across a selectively permeable membrane, molecules move across the membrane without the cell having to expend any extra energy. When water molecules move passively into or out of a cell, for example, this is called osmosis. Other small molecules may move across the membrane by the process of diffusion. This means that they move across the cell membrane from an area of high concentration to an area of low concentration. Oxygen molecules may diffuse from the lung cavity by passive transport into blood cells in the lung.

Selective permeability is the property of a living cell membrane which controls which molecules are allowed past the membrane.

Active transport is a vital mechanism used by living cells for selective permeability. This method is necessary for small molecules to move across the cell membrane in situations where the molecules need to move against a concentration gradient. Unlike passive transport, active transport gives the cell the ability to move molecules from an area of low concentration to an area of high concentration. This works by means of special channels called pumps, which are present in the cell plasma membrane, and that use up energy when they move molecules across the membrane. Active transport is often used by cells lining the stomach to absorb glucose, amino acids, and other nutrients.

Selective permeability occurs in the cells lining the stomach.

Vesicles are tiny pockets that may form in the cell membrane to aid in the transport of larger molecules. The vesicles allow the cell to take in or eject these molecules across the cell membrane. This process is called endocytosis when molecules are moved into the cell and exocytosis when molecules are moved out of the cell.

Selective permeability of membranes generally depends on the size of the molecules, the positive or negative charge of the molecules, and their solubility in water or oil. In plasma cell membranes, it also depends on many biological functions and biochemical reactions both within and outside each cell. It is one of a living cell's most vital biochemical attributes, and it is a fundamental part of most of the vital processes needed to support life.

What are the properties of a selectively permeable membrane?

A selectively permeable cell membrane is one that allows certain molecules or ions to pass through it by means of active or passive transport. Active transport processes require the cell to expend energy to move the materials, while passive transport can be done without using cellular energy.

What is an example of selective permeability?

In addition to the cellular membrane, another example of a selectively permeable membrane is the inner membrane of an egg.

What is the definition of selective permeability quizlet?

Selective permeability. Ability of the cell membrane to allow certain substances to pass through while keeping others out. Diffusion. The movement of particles or molecules from an area of high concentration to an area of low concentration.