Cell membrane Flashcards
Lipid molecules make up how much of the membrane?
50%
All lipid molecules are __________- that is they have a ___________ end and a ___________end
All lipid molecules are **amphiphilic **- that is they have a hydrophillic end and a hydrophobic end
What are the most abundant membrane lipids?
Phospholipids
What are the main phospholipids in animal cell membranes?
Phosphoglycerides
In addition to phospholipids, the lipid bilayers in many cell membranes contain what?
Cholesterol and glycolipids
What are the three components of cholesterol?
A polar head group, a rigid steroid ring structure, and a nonpolar hydrocarbon tail
The shape and _________ nature of the phospholipid molecules cause them to form ___________ spontaneously in ___________ environments.
The shape and **amphiphilic **nature of the phospholipid molecules cause them to form **bilayers **spontaneously in **aqueous **environments.
Lipid molecules spontaneously form what structures in aqueous environments?
Micelles
The fluidity of a membrane depends on what?
Its composition and the temperature
What do lipid droplets store?
Neutral lipids such as triacylglycerides and cholesterol esters
What are glycolipids?
Sugar-containing lipid molecules that are found exclusively in the non-cytosolic monolayer
What are the different ways in which membrane proteins associate with the lipid bilayer?
- a single alpha helix
- multiple alpha helices
- a beta barrel
- anchored to cytosolic surface
- by a covalently attached lipid chain
- by an oligosaccharide linker
- non-covalent interactions
What membrane protein is this?
A single and multipass alpha helix
What membrane protein is this?
A beta barrel
What cytosolic membrane proteins are these?
An amphiphatic membrane protein and a protein attached to a prenyl group
What exposed membrane protein is this?
A protein covalently linked via a disaccharide to phosphatidyl inositol, or known as a “GPI anchor”
What non-covalently attached membrane proteins are these?
External and internal peripheral proteins
The cell surface is usually coated with what?
Sugar residues, referred to as the carbohydrate layer
What can be used to solubilise membrane proteins?
Detergents, which are small amphiphilic molecules of variable structure.
Strong ionic detergents, such as ___, can solubilise even the most _____________ membrane proteins. This allows the proteins to be analysed by ___ ____________-____ electrophoresis.
Strong ionic detergents, such as SDS, can solubilise even the most **hydrophobic **membrane proteins. This allows the proteins to be analysed by SDS polyacrylamide-gel electrophoresis.
How to cells restrict the lateral movement of membrane proteins?
From interactions of the plasma membrane with an underlying cytoskeleton.
What filamentous protein is responsible for the biconcave shape in red blood cells?
Spectrin
