In cell membrane, on the basis of mass, proteins and lipids are present at a ratio of
**Core Concept**
The cell membrane is a complex structure composed of **lipids** and **proteins**, with the former providing the basic structural framework and the latter performing a wide range of functions. The ratio of proteins to lipids in the cell membrane is crucial for its integrity and function. This ratio can vary depending on the type of cell and its specific functions.
**Why the Correct Answer is Right**
The correct answer reflects the approximate ratio by mass of proteins to lipids in the cell membrane, which is generally about 50:50. This means that for every part of lipid, there is an equivalent part of protein by mass. This balance is essential for the proper functioning of the cell membrane, including transport, signaling, and cell-cell interactions. The **fluid mosaic model** of the cell membrane, which describes the membrane as a fluid phospholipid bilayer with embedded proteins, supports this ratio.
**Why Each Wrong Option is Incorrect**
**Option A:** This option suggests a much higher proportion of lipids, which is not consistent with the known composition of cell membranes.
**Option B:** This option suggests a very low proportion of proteins, which is not accurate given the critical roles proteins play in cell membrane function.
**Option D:** This option also does not reflect the known approximate equal mass ratio of proteins to lipids in cell membranes.
**Clinical Pearl / High-Yield Fact**
Remembering that the cell membrane is roughly equal in mass between proteins and lipids is crucial for understanding how the membrane functions in health and disease. This balance is key to the proper functioning of **transport proteins** and **receptors** embedded within the membrane.
**Correct Answer:** C. 50:50