ANP 1105 Lecture Notes - Lecture 2: Reuptake, Pinocytosis, Oligodendrocyte
Document Summary
The fluid mosaic model depicts the plasma membrane as an exceedingly thin structure composed of a double layer or bilayer, of phospholipids with embedded proteins. The proteins, many of which float in the fluid lipid bilayer, form a constantly changing mosaic pattern. Each lollipop-shaped phospholipid (cid:373)ole(cid:272)ule has a polar (cid:862)head(cid:863) that is (cid:272)harged a(cid:374)d is hydrophilic and an uncharged, non-polar (cid:862)tail(cid:863) that is (cid:373)ade up of t(cid:449)o fatt(cid:455) (cid:272)hai(cid:374)s a(cid:374)d is hydrophobic. The polar heads are attracted to water- the main constituent of both the intracellular and extracellular fluids- and so they lie on both the inner and outer surfaces of the membrane. The non-polar tails, avoid water and line up in the center of the membrane. All plasma membranes share a sandwich-like structure: they consist of two parallel sheets of phospholipid molecules lying tail to tail, with their polar heads bathed in water on either side of the membrane or organelle.