be differences in the \"sides\" of a cell when we talk about cellular polarity. (3pts) The
membranes of cells also show \"polarity\". Name at least 3 separate characteristics of the
membrane in the image below that illustrate polarity 1. Chol 0 Gang SPM OPI TM1 TM2 Acyl
cytoplasm 2. (3pts) The blue shaded regions of the membrane are lipid rafts, which show
differences in lipid and protein composition from other parts of the membrane. These differences
restrict movement of molecules into and out of the raft and also molecules within the raft. Which
of the following would you expect within a lipid raft? choose three answers a. increase in
cholesterol content b. decrease in cholesterol content c. increase in glycosphingolipids with
longer fatty acid tails d. increase in glycosphingolipids with shorter fatty acid tails e. increase in
unsaturated phospholipids f increase in saturated phospholipids
Solution
Ans
1. characterstics of the membrane that illustrate polarity -
a) glycolipids and GPI - linked proteins are exclusively located on the outer leaflet of the plasma
membrane. the carbohydrate groups are exposed to the outer surface.
b) The outer leaflet of the plasma membrane consists mainly of phosphatidylcholine and
sphingomyelin (assymetrical distribution)
c) phosphatidylethanolamine and phosphatidylserine are the predominant phospholipids of the
inner leaflet. A fifth phospholipid, phosphatidylinositol, is also localized to the inner half of the
plasma membrane.
2. following are expected within a lipid raft.
a. increase in cholesterol content .
b. increase in glycosphingolipids with longer fatty acid tails.
c. increase in saturated phospholipids.
This composition results in lateral phase separation and the generation of a liquid-ordered
domain..
membranes of cells also show \"polarity\". Name at least 3 separate characteristics of the
membrane in the image below that illustrate polarity 1. Chol 0 Gang SPM OPI TM1 TM2 Acyl
cytoplasm 2. (3pts) The blue shaded regions of the membrane are lipid rafts, which show
differences in lipid and protein composition from other parts of the membrane. These differences
restrict movement of molecules into and out of the raft and also molecules within the raft. Which
of the following would you expect within a lipid raft? choose three answers a. increase in
cholesterol content b. decrease in cholesterol content c. increase in glycosphingolipids with
longer fatty acid tails d. increase in glycosphingolipids with shorter fatty acid tails e. increase in
unsaturated phospholipids f increase in saturated phospholipids
Solution
Ans
1. characterstics of the membrane that illustrate polarity -
a) glycolipids and GPI - linked proteins are exclusively located on the outer leaflet of the plasma
membrane. the carbohydrate groups are exposed to the outer surface.
b) The outer leaflet of the plasma membrane consists mainly of phosphatidylcholine and
sphingomyelin (assymetrical distribution)
c) phosphatidylethanolamine and phosphatidylserine are the predominant phospholipids of the
inner leaflet. A fifth phospholipid, phosphatidylinositol, is also localized to the inner half of the
plasma membrane.
2. following are expected within a lipid raft.
a. increase in cholesterol content .
b. increase in glycosphingolipids with longer fatty acid tails.
c. increase in saturated phospholipids.
This composition results in lateral phase separation and the generation of a liquid-ordered
domain..
