Classification of Phospholipids

 Classification

Phospholipids are classified into two types.

1.        Glycerophospholipids (or) Phosphoglycerides that contain glycerol as alcohol.

2.        Sphingophospholipids that contain sphingosine as alcohol.

 

Glycerophospholipids

These are the major lipids that occur in biological membranes. They present in all plant and animal cells. They are abundantly present in heart, brain, kidney, egg yolk and soyabean. The important glycerophospholipids are lecithin, cephalin, phosphotidyl inositol, cardiolipin and plasmalogen.


The lecithins contain glycerol, fatty acids, phosphoric acid and choline (nitrogenous base). Lecithins generally contain a saturated fatty acid at a1 position and an unsaturated fatty acid at β postition.


The cephalin contains glycerol, fatty acids, phosphoric acids and ethanol amine as nitrogenous base.


Phosphatidyl inositol contains a hexahydric alcohol called as inositol.


Plasmalogens posses an ether link in a1 position instead of ester link. The alkyl radical is an unsaturated alcohol and they are found in brain and nervous tissue

Spingophospholipids

These are present in plasma membrane and myelin sheath. They are amphipathic lipids having polar head and non-polar tail. They contain an amino alcohol called shingosine. It is attached to a fatty acid by an amide linkage to form ceramide. Ceramide is linked to phosphoryl choline to form sphingomyelin, which is an important member of sphingophospholipids.

Comments

Post a Comment

Popular posts from this blog

Cell Membrane and its Functions

Image
  Cell Membrane The cell is enveloped and thus separated from its surroundings by a thin wall contains a rigid framework of polysaccharide chains crosslinked with short peptide chains. Its outer surface is coated with lipopolysaccharide. Cell membrane is also called as plasma membrane (or) plasma lemma. The pili, not found in all bacteria have extensions of the cell wall. The cell membrane contains about 45% lipid and 55% protein. The cell membrane or plasma membrane have an average thickness of 75A°. The principal lipids are phospholipids, sphingolipids and cholesterol. An important feature of these lipids is they are composed of hydrophobic (water - insoluble) hydrocarbon sections and hydrophilic (water soluble) units. The latter include charged units (eg. phosphate or amino groups) and uncharged units (eg. hexose). In water, such compounds orient themselves in such a way that only the hydrophilic section is exposed to water. The hydrophobic components of individual molecules ten...
Read more

Types of Living cells

Image
  Types of cells Two general types are recognised in nature. They are prokaryotic and eukaryotic cells. Prokaryotic cells Prokaryotes were the first cells to arise in biological evolution. They are very small and simple having only a single membrane. The cell membrane, is usually surrounded by a rigid cell wall. They are devoid of nucleus and membranous organelles such as mitochondria and endoplasmic reticulum etc. (Fig. 1.1). Eukaryotic cells Eukaryotic cells are presumably derived from prokaryotes. They are much larger and much more complex than prokaryotic cells (Fig. 1.2). They have nucleus and membrane bound subcellular organelles. Many of their metabolic reactions are segregated within structural compartments. The significant differences between prokaryotic and enkaryotic cells are: The eukaryotic cell structure is composed of (i) cell membrane, (ii) nucleus (iii) mitochondria (iv) endoplasmic reticulum (v) golgi apparatus (vi) ribosomes (vii) lysosomes and others. These spec...
Read more

Sub cellular Organelles

Image
  Sub cellular Organelles   Cell Membrane The cell is enveloped and thus separated from its surroundings by a thin wall contains a rigid framework of polysaccharide chains crosslinked with short peptide chains. Its outer surface is coated with lipopolysaccharide. Cell membrane is also called as plasma membrane (or) plasma lemma. The pili, not found in all bacteria have extensions of the cell wall. The cell membrane contains about 45% lipid and 55% protein. The cell membrane or plasma membrane have an average thickness of 75A°. The principal lipids are phospholipids, sphingolipids and cholesterol. An important feature of these lipids is they are composed of hydrophobic (water - insoluble) hydrocarbon sections and hydrophilic (water soluble) units. The latter include charged units (eg. phosphate or amino groups) and uncharged units (eg. hexose). In water, such compounds orient themselves in such a way that only the hydrophilic section is exposed to water. The hydrophobic compone...
Read more