Describe a selectively permeable membrane.?

Answer 1

The plasma membrane functions to isolate the inside of the cell from its environment, but it is imperative that such isolation not be complete. A large number of molecules must constantly transit between the inside and outside of the cell, most frequently one-at-a-time, but also in large packages. The plasma membrane functions as a selectively permeable membrane with exquisite selectivity regarding which molecules cross and which direction they are allowed to travel. In the simplest case, nutrients must be allowed to enter the cell and waste products to exit. Another critical task is to maintain an ionic composition inside the cell that is very different from that outside the cell.

Answer 2

The cell membrane, which is inside the cell wall and outside the cytoplasm, controls what leaves and enters the cell through selective permeability based on the negative and positive charges of the substances' ions. The cell membrane has two bipolar layers on its surface called polar, "head" and nonpolar, "tail." The polar allows water into the cell and the nonpolar doesn't allow the water into the cell. Some sunstances have a more positive charge ion than a negative charge, This means that the substance will be absorbed more rapidly into the cell, leading to overdose of the substance, but the cell has a specialized protein that controls the No. of that substance to be absorbed in the cell called the
Sodium-potassium pump. This protein takes out three sodium ions, becaues it has a positive charge and absorbs potassium ions, because it has a negative charge. That's how selective permeability works.

Answer 3

The plasma membrane (also known as cytoplasmic membrane, or cell membrane) is a semi-permeable membrane in the cell. Many studies about the structure of this membrane and how it works have been done.. The most well known is the (fluid mosaic) which clearly describes the structure of the cell membrane..

The cell membrane consist of phospholipid bilayer, glycoproteins, integral proteins, carbohydrates, and sterol (absent in bacteria)...

The integral proteins works as controllers for bodies that enter the cell, that's why it is permeable... it doesnt allow the entrance of all those bodies, that's why it is semi premeable...

The carbohydrates are attached to the integral protein, and helps in the self-recognition of the cell.

Beside being a semi-premeable membrane, the cell membrane in some organisms (that lack the mitochondrion or the chloroplast) contains the enzymes and bigments necessary for photosynthesis or breathing in general..

Hope this helped out..

Thanks

Answer 4

The cell membrane is responsible, along with the cell wall, for maintaining a balance between the outside world and the inside the cell. The cell membrane is a selectively permeable barrier that allows some substances to pass through to the inside of the cell while keeping others out. In order to understand how the cell membrane functions to regulate flow into and out of a cell, it is important to understand the structure of a typical membrane.

Answer 5

Permeable membranes surround cells, their function being to let some matter penetrate it into the cell, and other matter to stay out of the cell.

Answer 6

transport of material is one of the vital role for the cell.It offers a barrier between the cell contents and their environment ,allowing only substances to pass through it, thus it known as differentially permeable membrane

Answer 7

only certain things are allowed through the membrane

Answer 8

Well, the molecules have to show id before they get through.

Answer 9

kind of like a wall which only lets certain things through!