Flashcards in Chapter 12 Terms Deck (24):
Long hydrocarbon chains of various lengths and degrees of unsaturation terminated with carboxylic acid groups.
Are abundant in all biological membranes; a molecule is constructed from 4 components: one or more fatty acids, a platform to which the fatty acids are attached, a phosphate, and an alcohol attached to the phosphate.
A more complex alcohol that is sometimes a part of a phospholipid.
Phospholipids derived from glycerol.
The amino group of the sphingosine backbone is linked to a fatty acid by an amide bond. In addition, the primary hydroxyl group is esterified to phophorylcholine.
Are sugar containing lipids. In animal cells, they are derived from sphingosine.
The simplest glycolipid, which contains a single sugar residue, either glucose or galactose.
A more complex glycolipid, which contains a branched chain of as many as 7 sugar residues. Glycolipids are oriented in a completely asymmetric fashion with the sugar residues always on the extracellular side of the membrane.
The third major type of membrane lipid, which has a structure that is quite different from that of phospholipids. It's a steroid, built from 4 linked hydrocarbon rings.
A molecule containing both a hydrophilic and a hydrophobic moiety.
Aphipathic (amphiphilic) molecule
Composed of 2 lipid sheets; they hydrophobic tails of each individual sheet interact with one another, forming a hydrophobic interior that acts as a permeability barrier. The hydrophilic head groups interact with the aqueous medium on each side of the bilayer.
An aqueous compartment enclosed by a lipid bilayer.
Interact extensively with the hydrocarbon chains of membrane lipids, and they can be released only by agents that compete for these nonpolar interactions. Most span the lipid bilayer.
Integral membrane protein
Are bound to membranes primarily by electrostatic and hydrogen-bond interactions with the head groups of lipids. These polar interactions can be disrupted by adding salts or by changing the pH.
Peripheral membrane protein
Allows for the visualization of hydrophobicity over the length of a peptide sequence.
The rapid lateral movement of membrane proteins and lipids.
Describes the overall organization of biological membranes; membranes are two-dimensional solutions of oriented lipids and globular proteins.
Fluid mosaic model
Are regions of membranes with a distinct, characteristic structural composition and that appear to act as platforms to colocalize proteins involved in intracellular signaling pathways.
Receptor binding on the surface of the cell induces the membrane to invaginate, with the assistance of specialized intraceullular proteins such as clathrin. The process results in the formation of a vesicle within the cell.
Specialized protein which polymerizes into a lattice network around the growing membrane bud during a receptor mediated endocytosis.
In the bloodstream, iron is tightly bound to this protein, which can bind two Fe+3 ions with a dissociation constant of 10^23 M at neutral pH.
Cells requiring iron express this in their plasma membranes. Formation of a complex between this and iron-bound transferrin initiates receptor-mediated endocytosis.
Vesicles involved in receptor-mediated endocytosis.