Chapter 7 - Lipids and Biological membranes

Flashcards about Lipids and Biological Membranes.

Amphiphilic molecules

Molecules that, in aqueous solutions, aggregate to form micelles.

Micelle formation

Molecular arrangement of lipids which eliminates unfavorable contacts between water and the hydrophobic tails of the amphiphiles, yet permits the solvation of the polar head groups.

Spheroidal micelle formation

Lipids can pack efficiently to form this type of micelle.

Lipid bilayers

Phospholipids and sphingolipids with two hydrocarbon tails that give them a somewhat rectangular cross section, better known as this term

Glycerophospholipids or phosphoglycerides

An amphiphilic lipid in which two fatty acyl groups are attached to a glycerol – 3 – phosphate whose phosphate group is linked to a polar group (X).

Sphingolipids

A derivative of the C18 amino alcohol sphingosine.

Phospholipid bilayer

Composed of two layers of lipids, each containing a hydrophobic tail and a hydrophilic head.

Transverse diffusion

The transfer of a lipid molecule across a bilayer.

Flip-flop

Another term for Transverse diffusion.

Lateral diffusion

The movement of a lipid within one leaflet of a bilayer.

Fluidity of a lipid bilayer

A critical property that allows lipids and proteins to move laterally within the membrane and is influenced by factors like temperature, lipid composition, and the presence of cholesterol.

Transition temperature (melting temperature)

The temperature at which a lipid bilayer shifts from a gel-like solid to a more fluid liquid crystal form.

Integral membrane proteins (intrinsic membrane proteins)

Membrane proteins that interact with only one leaflet of the membrane (monotopic), cross the entire membrane, or are anchored by different types of lipids.

Peripheral membrane proteins (extrinsic membrane proteins)

Membrane proteins that are only temporarily associated with the membrane and can be easily removed using any polar solvent.

Compartmentalization

Membranes define boundaries within cells, creating distinct internal environments for specialized functions.

Selective permeability

Cell membranes regulate what enters and exits the cell, allowing selective transport of ions, nutrients, and waste.

Signal transduction

Membranes contain receptor proteins that detect chemical signals and initiate intracellular signaling cascades.

Energy conversion

In mitochondria and chloroplasts, membranes are the sites of ATP production.

Structural support and shape

Membranes provide mechanical support, helping cells maintain their shape.

Molecular recognition and cell identity

Membrane proteins and glycoproteins act as identification markers, enabling immune recognition, tissue formation, and cell–cell communication.

Cell movement and interaction

Membranes facilitate cell motility and interactions with the extracellular matrix, playing a role in endocytosis and exocytosis.

Fatty acids

Carboxylic acids with long-chain hydrocarbon side groups.

Sphingolipids

Lipids where Ceramides are the parent compounds of the more abundant molecules of these lipids.

Sphingomyelins

The most common sphingolipids, are ceramides bearing either a phosphocholine or a phosphoethanolamine head group.

Cerebrosides

Ceramides with head groups that consist of a single sugar residue which makes these lipids glycosphingolipids.

Gangliosides

Ceramides with attached oligosaccharides that include at least one sialic acid residue.