Chapter 5, Problem 1TYU

In what way do the membranes of a eukaryotic cell vary?

1. A.    Phospholipids are found only in certain membranes.
2. B.     Certain proteins are unique to each kind of membrane.
3. C.     Only certain membranes of the cell are selectively permeable.
4. D.    Only certain membranes are constructed from amphipathic molecules.

Summary Introduction

Introduction:

The lipid bilayer model of the membrane consists of proteins and lipids with triacylglycerols. This structure maintains the fluidity of membrane. Various phospholipids are present in the membrane. They consist of a hydrophilic head and a hydrophobic tail. The presence of the lipid cholesterol provides flexibility to the membrane at various temperatures. Various unique proteins are present in the membrane like cell signaling proteins and growth receptors.

Answer to Problem 1TYU

Correct answer:

The membrane is unique and consists of lipids and proteins. The proteins present in the membrane are specific and form an essential part of cell signaling and growth receptor signaling response. Therefore, option (B) is correct.

Explanation of Solution

Reason for the correct statement:

The membrane of the cells contains unique proteins. The proteins are present in the membrane are specific and help in the signaling inside the cells by the activation of the protein growth factor receptors.

Option (B) is given as “Certain proteins are unique to each kind of membrane”.

As, “the proteins present in the membrane of a eukaryotic cell are unique and perform specific functions according to the type of proteins present in the cell”, it is the right answer.

Hence, option (B) is correct.

Reasons for the incorrect statements:

Option (A) is given as “Phospholipids are found only in certain membranes”. Phospholipids are present in the membranes, but the proteins present in the membrane are unique, specific and diverse. So, it is the wrong answer.

Option (C) is given as “Only certain membranes of the cell are selectively permeable”.  The cell membranes are selectively permeable to the movement of the various solutes like glucose and ions, which cross the membrane across the protein channels. They are unique and specific to the membrane. So, it is a wrong answer.

Option (D) is given as “Only certain membranes are constructed from amphipathic molecules”.

The membrane molecules are amphipathic, but the proteins formed in the membrane are specific and unique. So, it is a wrong answer.

Hence, options (A), (C), and (D) are incorrect.

Conclusion

The proteins present in the membrane are unique, specific and are of various types. These include the cell signaling proteins, growth factor receptor proteins, post-translationally modified proteins, blood group proteins, and cluster of differentiation receptor proteins.