Membranes Flashcards
What makes up a phospholipid molecule in the bilayer?
HYDROPHILIC HEAD
Polar head group
Phosphate group
Glycerol
HYDROPHOBIC TAIL
Two fatty acid chains
What is the most common polar molecule occurring in the phospholipid bilayer as a head group?
Choline, followed by serine, inositol and ethanolamine
What is the most common phospholipid in the cell membrane?
Phosphotidylcholine
What are four commonly-occurring phospholipids in the bilayer?
Phosphatidylcholine, phosphatidylethanolamine, phosphatidyl serine, phosphatidyl inositol
The first two have net charge of 0, while the last two have a net charge of -1
What makes up a glycolipid?
A sugar (glucose or galactose), serine, and two fatty acid chains
What function do carbohydrates usually serve in the membrane?
Cell-cell recognition
What are the three types of movements that occur in the phospholipids of the bilayer, and which is the least frequent?
Lateral movements, rotation, and flip-flopping across the membrane. While lateral movements occur 10^7 times per second, flip-flopping only occurs once per month
What function does cholesterol serve in the bilayer?
Cholesterol inserts itself with its polar hydroxyl group near the polar head group of the phospholipids, and its non-polar tail near the hydrophobic tails. It partially immobilizes the regions of fatty acids around it, stiffening the bilayer.
Glycolipids and sphingomyelin are only on the _______________ leaflet
Extracellular
Phosphatidylcholine is mostly on the _______________ leaflet
Extracellular
Phosphatidylinositol, phosphotidylserine, and phosphotidylethanolamine are mostly on the _______________ leaflet
Intracellular
True or False:
Cholesterol is mostly on the outer extracellular leaflet
FALSE
Cholesterol is evenly distributed throughout both leaflets, and spontaneously shuttles back and forth between them
