Question

Name two glycerophospholipids found in eukaryotic cell membranes and two sphingolipids. What fraction of the lipid in most plasma membranes is cholesterol, and how does cholesterol content affect membrane fluidity?

Short answer

Question: Name two glycerophospholipids and two sphingolipids found in eukaryotic cell membranes, determine the fraction of cholesterol present in most plasma membranes, and describe how the cholesterol content affects the membrane fluidity. Answer: Two examples of glycerophospholipids in eukaryotic cell membranes are phosphatidylethanolamine and phosphatidylcholine. Two examples of sphingolipids in eukaryotic cell membranes are sphingomyelin and a glycosphingolipid like a cerebroside. The fraction of cholesterol in most plasma membranes is about 30-40%. Cholesterol affects membrane fluidity by adjusting its rigidity through inserting itself between the fatty acid chains of lipids. At high temperatures, cholesterol decreases fluidity, and at low temperatures, it prevents tight packing, maintaining or increasing fluidity. Overall, cholesterol maintains membrane fluidity over a range of temperatures.

Step-by-step solution

Name Glycerophospholipids

In eukaryotic cell membranes, two examples of glycerophospholipids are phosphatidylethanolamine and phosphatidylcholine.

Name Sphingolipids

Similarly, two examples of sphingolipids found in eukaryotic cell membranes are sphingomyelin and a glycosphingolipid, such as a cerebroside.

Cholesterol Content in Plasma Membranes

The fraction of cholesterol in most plasma membranes is about 30-40%.

Effect of Cholesterol on Membrane Fluidity

Cholesterol affects membrane fluidity by inserting itself between the fatty acid chains of lipids, thus adjusting the membrane's rigidity. At high temperatures, cholesterol restricts the movement of fatty acid chains, decreasing the membrane fluidity. Conversely, at low temperatures, cholesterol prevents tight packing of fatty acid chains, thus maintaining or increasing the membrane fluidity. Overall, cholesterol acts as a buffer, maintaining the membrane fluidity over a range of temperatures.