Why is the membrane described as a phospholipids bilayer?

Answer 1

The phospholipid bilayer is fluid due to the unsaturated hydrocarbon tails of phospholipids found in the hydrophobic region. These unsaturated hydrocarbon tails do not have all the hydrogen it can possibly have, so carbon forms a double bond. This double bond within the tails causes a kink in the tail, which prevents tight packing within the hydrophobic region. Preventing the tight packing makes the bilayer more fluid, which all membranes need to be fluid for it to be able to work. Being solid will alter the permeability and affect the enzymes.

Answer 2

The usual phospholipid that we encounter is those found in the cell membrane, namely the membrane phospholipid. They are the predominant lipids of cell membrane.

They can act as:

1) reservoir of intracellular protein messengers such as phosphoinositol biphosphate. This is obtained from the cleavage of phosphatidylinositol by Phospholipase C. Phosphoinositol biphosphate is one of the most important secondary messenger in the cell signalling pathway of human.

2) anchors to cell proteins

On the other hand, phospholipids also exist out of cell membrane. These are non-membrane phospholipid. Some examples are:

1) Dipalmitoylphosphatidylcholine (DPPC) is a component of lung surfactant. Secreted by granular pneumocytes, it decreases surface tension of fluid layer, reducing pressure required to reinflate alveoli.

2) Phospholipid is also an essential component of bile, where their detergent properties (amphipathic) aid in the solubilzation of cholesterol. Phosphatidylcholine (lecithin) and bile salts are both the major components of bile.

3) Act as building blocks of the biological cell membranes in virtually all organisms

4)Participate in the transduction of biological signals across the membrane.

5)Act as efficient store of energy as with triglycerides.

6)Play an important role in the transport of fat between gut and liver in mammalian digestion.

7)An important source of acetylcholine which is the most commonly occuring neurotransmitter substance occuring in mammals.

Answer 3

The membrane is described as a phospholipid bilayer because it consists of two layers of phospholipid molecules arranged with their hydrophilic (water-attracting) heads facing outward and their hydrophobic (water-repelling) tails facing inward. This structure forms a barrier that separates the internal cellular environment from the external environment.

Answer 4

It is described as a phospholipids bilayer because there are two layers of phospholipid molecules.