NEET BIOLOGY

Detailed explanation-1: -Nucleic acids are absent in the plasma membrane.

Detailed explanation-2: -Final Answer: Proline is not a constituent of the cell membrane.

Detailed explanation-3: -Nucleic acids are not structural components of cell membranes (ribosomes and nucleus are the main places where they are found). However, being open system, cell exchanges chemicals with its surrounding and cellular membrane can transport nucleic acids as well.

Detailed explanation-4: -The cell membrane consists of three classes of amphipathic lipids: phospholipids, glycolipids, and sterols. The amount of each depends upon the type of cell, but in the majority of cases phospholipids are the most abundant, often contributing for over 50% of all lipids in plasma membranes.

Detailed explanation-5: -As discussed in Chapter 2, the plasma membranes of animal cells contain four major phospholipids (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and sphingomyelin), which together account for more than half of the lipid in most membranes.