Q:

What is the cell membrane made of?

A:

Quick Answer

The cell membrane is comprised of phospholipids and proteins. The phospholipids are oriented so that their hydrophilic, polar heads face outwards and their hydrophobic, non-polar tails face inwards toward the middle of the cell. Proteins dot the cell membrane to allow solutes to be transported in and out of the cell membrane.

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Full Answer

The cell membrane is a biological membrane that separates the interior of the cell from the outside environment. It is selectively permeable and allows ions and small polar molecules through via passive diffusion. Large molecules such as proteins must be transported into the cell via transmembrane or carrier proteins that are embedded in the membrane. Cell membranes also allow water to pass through them via osmosis. Cell membranes are flexible and allow the cell to be fluid and to maintain their volume as they change shapes. They are also involved in a variety of cellular functions. These include cell adhesion, ion conductivity and cell signaling. Cell membranes can also be very diverse. In eukaryotes, they are single-layered and follow the fluid mosaic model. In prokaryotes, the cell membrane is surrounded by an outer membrane. The cell membrane and outer membrane are separated by a periplasmic space. However, some prokaryotes have no cell membrane at all.

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Related Questions

  • Q:

    Why is the cell membrane said to be selectively permeable?

    A:

    The cell membrane is said to be selectively permeable because it lets certain substances pass through while restricting the passage of others. The actual structure of the cell membrane allows free passage or restricts movement of substances across the membrane. Three ways in which the cell membrane controls the movement of substances is simple diffusion, facilitated diffusion and active transport.

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  • Q:

    What keeps cell membrane from collapsing?

    A:

    According to science writer Clare Smith for SeattlePi, the cell membrane is kept from collapsing by its phospholipid bilayer, maintenance of the correct temperature, a cytoskeleton and cell junctions. These are necessary because the cell membrane is one of the most crucial components of a cell.

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  • Q:

    Where is the cell membrane located?

    A:

    The cell membrane is a semipermeable lipid bilayer that surrounds the cytoplasm of all cells. In animal cells, it is the outermost layer of the cell. In plants, fungi and some bacteria, a cell wall surrounds the cell membrane to form the cell's outermost layer.

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  • Q:

    What would happen if there was no cell membrane?

    A:

    The cell membrane is essential to the life of the cell and without it, the cell dies. If all the cells in an organism suddenly die, the organism itself dies as well.

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