Question

Although bacterial membranes do not contain cholesterol, some contain compounds called hopanoids, which have five fused rings and are thought to play a similar role in membrane fluidity that cholesterol does in eukaryotes. Based on this similarity in function, what effect do you expect hopanoids to have on bacterial membrane fluidity at low T’s? at high T’s? Explain.

Answer 1

Answer:

At low Ts= Hopanoids increase membrane fluidity

At higher Ts= Hopanoids reduce the membrane fluidity

Explanation:

Bacterial membranes lack cholesterol but have hopanoids. Hopanoids are synthesized from the same precursor as the steroid. The hopanoids also have five fused ring structures like that of cholesterol.  The amphipathic nature of hopanoids allows them to maintain the membrane fluidity under low and higher temperature conditions.

When the temperatures are higher, the hopanoids serve to reduce the membrane fluidity by their ability to interact with polar heads and non-polar tails of the membrane phospholipids. At lower temperatures, hopanoids insert themselves between the non-polar tails of phospholipids to increase the membrane fluidity.