Question

Which of the following is NOT one of the functions of proteins found in the phospholipid bilayer of a cell membrane?

A) to break down material that enters through the cell membrane

B) to act as receptors that recognize and transmit hormonal messages

C) to provide an attachment point for other cells

D) to transport material across the membrane into the cell

Answer 1

The function that is NOT one of the roles of proteins in the phospholipid bilayer of a cell membrane is to break down material that enters through the cell membrane. This is typically a function of peripheral proteins, which can act as enzymes, not integral membrane proteins.

Step-by-step explanation:

The question concerns the functions of proteins in the phospholipid bilayer of a cell membrane. Options provided include activities such as the breakdown of material, acting as receptors, providing attachment points, and transporting material across the membrane. Functions of proteins in the phospholipid bilayer include serving as integral proteins that form transporters that move ions and molecules across the membrane, peripheral proteins that may act as enzymes or be part of the cell's recognition sites, and involvement in adhesion. They also play a role in signal transduction as receptors.

The correct answer is: A) to break down material that enters through the cell membrane. This function is not a role of proteins within the phospholipid bilayer. Instead, proteins involved with enzymatic breakdown, such as digestive enzymes found on the surface of intestinal cells, are considered peripheral proteins rather than integral membrane proteins.