Question

A consistent response in many organisms to changing environmental temperatures is the restructuring of cellular membranes.In some fish, phosphatidylethanolamine (PE) in the liver microsomal lipid membrane contains predominantly docosahexaenoic acid, 22:6 at C-2 of the glycerol-3-phosphate backbone and then either a saturated or monounsaturated fatty acyl group at C-1. Which of the following statements are False?
a. At 10 degrees Centigrade a lower percentage of PE molecules contain saturated fatty acyl groups at C-1 when compared to fish acclimatized at 30 degrees Centigrade.
b. At 10 degrees Centigrade a higher percentage of PE molecules contain saturated fatty acyl groups at C-1 when compared to fish acclimatized at 30 degrees Centigrade.
Ñ. At 30 degrees Centigrade a lower percentage of PE molecules had monounsaturated acyl groups at C-1 compared to that observed at 10 degrees Centigrade.
d. At 30 degrees Centigrade a higher percentage of PE molecules had monounsaturated acyl groups at C-1 compared to that observed at 10 degrees Centigrade.
e. The purpose of membrane restructuring with a change in temperature is to maintain fluidity of the membrane.

Answer 1

Answer:

The false statements are :

b. At 10 degrees Centigrade a higher percentage of PE molecules contain saturated fatty acyl groups at C-1 when compared to fish acclimatized at 30 degrees Centigrade.

d. At 30 degrees Centigrade a higher percentage of PE molecules had monounsaturated acyl groups at C-1 compared to that observed at 10 degrees Centigrade.

Explanation:

The false statements are :

b. At 10 degrees Centigrade a higher percentage of PE molecules contain saturated fatty acyl groups at C-1 when compared to fish acclimatized at 30 degrees Centigrade.

d. At 30 degrees Centigrade a higher percentage of PE molecules had monounsaturated acyl groups at C-1 compared to that observed at 10 degrees Centigrade.

Reason -

When temperature decreases,  the proportion of unsaturated fatty acids increases and saturated fatty acids decreases that also decreases the fluidity of the membrane and thereby make it stiff.

When temperature increases, the proportion of unsaturated fatty acids decreases and saturated fatty acids increases that makes the cell membrane more fluidic.

So, the temperature changes restructures the membrane with respect to fluidity of membrane.

Therefore,

At 10° Celsius, at C-1 of glycerol, the proportion of unsaturated fatty acids increases and saturated fatty acids decreases.

At 30° Celsius, the proportion of unsaturated fatty acid decreases and saturated fatty acid increases.