The following about biological membrane is correct
|A||They are symmetric bi-leaflet structure|
|B||Their constituent lipid & protein moieties are held together by covalent interaction|
|C||They are rigid assemblies of protein, lipid & carbohydrates|
|D||Their lipid moieties are amphipathic in nature|
a. Membranes are complex structures composed of lipid, proteins and carbohydrates.
b. Membranes are asymmetric sheet like enclosed structures with an inside and an outside surface.
These sheet like structures are Non-covalent assembles that are thermodynamically stable and metabolically active.
c. Membrane lipids are amphipathic. All major lipids [eg. PL, glycosphingolipids, and cholesterol] of membranes contain both hydrophobic regions and hydrophilic regions, and are therefore Amphipathic
d. Membrane lipids form bilayer.
e. Membranes and their component are dynamic structure (the fluid mosaic model of membrane structure is widely accepted now, given by singer and Nicolson).
6. Membranes contain: -
a. Integral proteins → asymmetrically distributed — across the membrane bilayer.
b. Peripheral proteins - do not interact directly with phospholipids
c. Integral proteins - most of the membrane proteins fall into the integral class, usually globular and
amphipathic, generally span the bilayer membrane (called Transmembrane protein); and consists of two hydrophilic ends separated by an intervening hydrophobic region.
Membrane is semi permeable. - Membrane is 7.5 nm (75 Angstrom unit) thick
Major Lipids are phospholipids (PL) such as phosphatidyl choline and phosphatidylethanolamine (head end is polar or hydrophilic and tail ends are relatively- non polar or Hydrophobic)