L31 Structure and Function of Plasma Membrane Flashcards
Plasma membranes have been described as having ‘a trilaminar staining pattern’. Explain this.
When stained with osmium there appears to be 2 dark lines separated by a lightly stained central zone.
Resembles train tracks.
Hydrophilic heads form dark layers and the middle is the hydrophobic tails (which do not stain).
How much of a cell membrane is made of lipid molecules?
30-80%
What lipids are found in cell membranes?
Phospholipids, glycolipids, sterols
How long are phospholipid fatty acid ‘tails’?
14-24 carbon atoms long
When surrounded by water, cone-shaped (single chain) lipid molecules aggregate to form a __?__
micelle
When surrounded by water, cylindrical-shaped (double tailed) lipid molecules aggregate to form a __?__
bilayer
What is a glycerol based phospholipid known as?
Phosphoglyceride
What are the main phosphoglycerides in the plasma membrane?
Phosphatidylcholine
Phosphatidylethanolamine
Phosphatidylserine (-)
Phosphatidylinositol
Which of these molecules has an overall negative charge?
a) Phosphatidylcholine
b) Phosphatidylethanolamine
c) Phosphatidylserine
d) Phosphatidylinositol
c) Phosphatidylserine
What is the main sphingolipid in the plasma membrane?
Sphingomyelin
What type of molecule forms the head of a phospholipid?
A polar molecule
e.g. choline, ethanolamine, serine, inisitol
In a phospholipid, the fatty acid chains need to attach to __?__
glycerol or sphingosine
How are glycolipids formed?
Addition of CHO group(s) to lipids.
Glycerol-based: glycolipid
Sphingosine-based: sphingolipid
Combo of glycerol and sphingosine: glycosphingolipid
What are the most common glycosphingolipids?
- Cerebrosides
- Gangliosides
In what cells are glycosphingolipids prominent?
Nerve cells.
Think of the names of the most common glycosphingolipids:
- Cerebroside
- Ganglioside