Question

The term cell membrane was coined by
a. Nageli and Cramer
b. Flemming
c. Sachs
d. Piowe.

Answer 1

Hint: Cell membrane is also called as Plasma membrane and it is also termed as biological membrane where it separates the interior of the cell and component to the exterior or outside, or from the environment, and this membrane is made up of a various number of components.

Complete answer:
Composition of the cell membrane.
- The cell membrane majorly consists of three types of amphipathic lipids, they are phospholipids, glycolipids, and sterols. And the term cell membrane was coined by Nageli and Cramer.
- The percentage of different types of lipids varies from cell to cell, in a majority of the cells, the abundant one is phospholipids which constitutes 50% of all, and glycolipids form only 2% and the rest is formed by the sterols.
- When coming to the eukaryotic cells, the plasma membrane consists of 50% of lipids and 50% of proteins by weight.
- The fatty chains in the phospholipids and glycolipids always contain an even number of carbon atoms, and the most common ones are 16 and 18 carton atom fatty chains.
- The fatty acids may be saturated or unsaturated, and it is present in form of cis.
- Carbohydrates in the plasma membrane are present either in the form of glycoproteins, and glycolipids.
- The glycocalyx is an important feature, which is present in all types of cells and especially in the epithelial cells along with microvilli.
- So the total thickness of the cell membrane is 50nm, they consist of phospholipids, proteins, and the carbohydrates, but among them, proteins are large in size and form the mass of the cell, whereas phospholipids are small in size but very large in number, and carbohydrates are fewest among all.

Hence, the correct answer is option (A).

Note: The second major components of the cell membrane are proteins, and they are called integrated proteins, as they are into the structure of the cell, and these proteins are large in size and forms most of the mass of the cell membrane, and each cell membrane contains up to 20-25 amino acids.