Question

Which of the following responses is NOT likely to oocur when a bacterial culture growing at 37C is transferred to a 25C incubator?

A. Initial decrease in membrane fluidity

B. Gradual replacement of short chain fatty acids with longer-chain fatty acids in the membrane.

C. Gradual replacement of stearate for oleate in the membrane.

D. Incorporation of more cholesterol into the membrane

Answer 1

Answer

When a bacterial culture growing at 37oC is transferred to a culture growing at 25oC, the membrane fluidity decreases since the temperature is decreased and there would be the replacement of synthesis of saturated fatty acid (stearate) for unsaturated fatty acid (oleate) because unsaturated fatty acids will increase the membrane fluidity.

The unlikely response would be the gradual replacement of short-chain fatty acids with longer-chain fatty acids in the membrane since longer chain fatty acids tend to decrease membrane fluidity so this will not occur. Bacteria cannot synthesize sterols and thus they lack sterols but possess sterol-like hopanoids. Thus, the unlikely response will be the incorporation of more cholesterol into the membrane.

Thus, the answers are option (B) and (D).