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Cell membranes are made up of a phospholipid bilayer.. they have a hydrophilic (water loving) head and two hydrophobic (water fearing) tails. Phospholipids contain a phosphate group and a lipid group, that's why they are called that.

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14y ago
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11y ago

The predominant constituent of the cell membrane consists of two layers of phospholipids. The two layers are sandwiched together with the hydrophobic, lipid component in the middle of the layers and the charged, hydrophilic phosphate component directed outwards. This membrane is permeable to some materials, but communication and transport across the membrane is facilitated by protein receptors and channels. These proteins typically exist in clusters of functional units, surrounded by a vast expanse of phospholipids, much like objects on the surface of the sea...

The metaphor shouldn't be taken too far however. The phospholipid "sea" is extremely shallow. And the proteins aren't floating on the surface but anchored in place through interactions with hydrophobic elements of the bilayer. Maybe a better metaphor would be rocks frozen into the ice of a skating rink where the ice is the phospholipid bilayer and the rocks are the proteins.

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7y ago

Most of these channels are active pumps powered by ATPand selectively transport certain chemicals either into or out of the cell. They oppose the direction of passive osmotic transport.

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7y ago

The main importance of protein channels in cell membranes is to mediates passive transport across the biological membrane by forming an aqueous channel through which solutes of appropriate size and charge can difuse. Examples of protein channels are Na+/K+ channel, Ca+2 channel, and porins (present in the outer membrane of gram-negative bacteria).

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7y ago

Somethings that must go through the membrane need a protein channel.

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Q: Why is the cell membrane described as a phopholipids?
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2 layers of these form much of the cell membrane?

A double layer, known as a bilayer, of phopholipids forms the main part of the cell membrane.


What forms an envelope around the cell described as and selectively permeable?

The plasma membrane (cell membrane).


What is described by the fluid mosaic model?

The cell membrane.


How is the cell membrane of Achaea different?

They phopholipids have an ester link between glycerol and the fatty acid chain instead of the prokaryotic ether link. This makes it less fluid at extreme temps.


Which part of a cell controls which substances can enter?

The cell membrane. It is described as semipermeable


Which cell organelle synthesizes the lipids that make up the bulk of cell membranes?

The cell membrane is a lipid bilayer, composed of phopholipids: A glyerol molecule with two fatty-acid groups at one end and a phosphate group at the other.Phospholipids are synthesised in the cytoplasm next to the endoplasmic reticulum. The ER sythesthies the lipids, and contains enzymes that catalyse the production of phopholipids such as Glycerol-3-phosphate acyltransferase. The phospholipids produced migrate naturally to the internal face of the membrane, and flippase moves them to the outer face.


Do red blood cells have a cell membrane?

Yes, red blood cells (erythrocytes) have a cell membrane, but they don't contain a nucleus- thus they're described as enucleate.


What type of lipid molecules do membranes consist of?

Phopholipids - They have a hydrophillic head that is positioned to the inside of the cell and the outside environment. They also have hydrophobic tails that point towards each other inside the membrane. This is why cell membranes are referred to as lipid bilayers. They are 2 layers of phospholipids organzied by their interaction with water.


Why is the cell membrane described as being a selective barrier?

Cell membranes are selective barriers because they only let certain substances pass through and therefore ensures the cells survival.


What has a polar head and non polar tail in a cell?

The phospholipid bilayer, otherwise known as the cell membrane contains many structures such as these. The individual units you speak of are called phopholipids, and are usually desribed as having a hydrophilic (polar) head group and a hydrophobic (non-polar) tail group. Hope this helps


What regulates passage of materials into and out of cells?

The cell membrane controls movement of materials in and out of the cell.


What organization is described as being a fluid mosaic model?

The phospholipid bilayer, also known as the cell membrane.