Which of the Following is Correct Regarding the Composition of Various

Question

Which of the following is correct regarding the composition of various biological membranes?
A) Bacterial plasma membranes are often composed of one main type of phospholipid and lack cholesterol.
B) Cholesterol in the eukaryotic plasma membrane induces phase transition to the gel state.
C) Inositol phospholipids are the most abundant lipids in the endoplasmic reticulum membrane.
D) The mitochondrial and bacterial membranes are rich in glycolipids.
E) Yeast cells synthesize more fatty acids with cis?-double bonds when the temperature in the environment rises.

Accepted Answer

Often one main type of phospholipid makes up the membrane in a bacterium, and these membranes lack cholesterol. Glycolipids are also rare in the mitochondrial and bacterial membranes, as are the functionally important phosphoinositides in eukaryotic membranes. The role of cholesterol in membrane fluidity and phase transition is a complicated one and depends on many variables, but at concentrations found in eukaryotic membranes, cholesterol prevents the packing of phospholipids into the gel state. Unsaturated fatty acids enhance the fluidity of the bilayer, as does the rise in temperature.