Question

Describe how these molecules are able to have parts that are inside the membrane and parts that are outside of it.

A) Amphipathic molecules have polar and nonpolar regions, allowing them to interact with both water and lipid components of membranes.
B) Hydrophilic molecules have polar regions that interact with water, while hydrophobic molecules have nonpolar regions that stay inside the membrane.
C) Lipid molecules have both water-attracting and water-repelling portions, enabling them to position within and outside the membrane.
D) Molecules are selectively permeable, allowing some to be inside the membrane and others outside.

Answer 1

Phospholipid molecules are amphipathic, with hydrophilic 'heads' that interact with water and hydrophobic 'tails' that avoid water, allowing them to form a bilayer that is the basis of cell membranes. The correct option is A) Amphipathic molecules have polar and nonpolar regions, allowing them to interact with both water and lipid components of membranes.

Step-by-step explanation:

Molecules such as phospholipids are able to have parts inside the membrane and parts outside of it due to their amphipathic nature. An amphipathic molecule has both a hydrophilic (water-loving) region and a hydrophobic (water-fearing) region. The hydrophilic part, which is the phosphate group or the 'head', is attracted to the water present inside and outside the cell.

The hydrophobic part, which consists of fatty acid chains known as 'tails', repels water and aligns in the interior of the membrane, away from the aqueous environment. This amphipathic property allows the phospholipids to form a bilayer, which is the fundamental structure of cell membranes, creating a barrier that separates the fluid inside the cell from the fluid outside. The correct option is A) Amphipathic molecules have polar and nonpolar regions, allowing them to interact with both water and lipid components of membranes.