Cell Membranes

Question 1

A 1-year-old girl was brought to the local clinic because of severe abdominal pain. She is pale-skinned, shows marked mental retardation, and has an enlarged abdomen. After genetic testing the doctor diagnosed her with Niemann-Pick's disease. The symptoms of this disease are due to the accumulation of which one of the following lipids?
A. Spingomyelin
B. Phosphatidylcholine
C. Phosphatidylserine
D. Cerebroside
E. Ceramide

Answer 1

A. Spingomyelin

Question 2

A medical student was studying the fluidity of the plasma membrane of hippocampal neurons. He cultured cells in the presence of a high concentration of fluorescently labelled PUFAs. Examination of the cells under a microscope showed bright fluorescence around the boundary of the cells suggesting that the PUFAs were incorporated into the neuronal membrane. Which of the following statements is the most accurate?
A. The plasma membrane of these cells is likely rigid
B. The plasma membrane of these cells is likely fluid
C. The plasma membrane of these cells has high cholesterol
D. The plasma membrane of these cells has phosphatidyl serine facing the outside of the bilayer
E. The plasma membrane of these cells has a 10-fold increase in integral membrane proteins

Answer 2

B. The plasma membrane of these cells is likely fluid