Cell membrane pores are not made of a single, defined material. They are formed by protein complexes embedded within the cell membrane. These proteins are arranged in a specific way to create a channel through the membrane, allowing for the passage of molecules and ions.

Here's a breakdown:

* Membrane proteins: The primary component of pores are integral membrane proteins. These proteins have hydrophobic regions that interact with the lipid bilayer of the cell membrane, anchoring them in place.

* Channel formation: Multiple protein subunits assemble to form the pore structure. The specific arrangement and properties of these proteins determine the size, selectivity, and function of the pore.

* Types of pores: There are various types of protein complexes that form pores, each with different characteristics:

* Ion channels: Allow the passage of specific ions (e.g., sodium, potassium, calcium) across the membrane.

* Aquaporins: Facilitate the movement of water across the membrane.

* Nuclear pore complexes: Large, intricate structures that regulate the transport of molecules between the cytoplasm and the nucleus.

Therefore, cell membrane pores are not made of a single material like a "hole" in the membrane, but rather are dynamic structures formed by the complex arrangement of proteins. These pores are crucial for maintaining cell function and communication.