What type of molecules can easily pass through the cell membrane?

Water diffusion is called osmosis. Oxygen is a small molecule and it's nonpolar, so it easily passes through a cell membrane. Carbon dioxide, the byproduct of cell respiration, is small enough to readily diffuse out of a cell. Small uncharged lipid molecules can pass through the lipid innards of the membrane.
A.

What type of molecule forms a lipid bilayer?

All of the lipid molecules in cell membranes are amphipathic (or amphiphilic)—that is, they have a hydrophilic (“water-loving”) or polar end and a hydrophobic (“water-fearing”) or nonpolar end. The most abundant membrane lipids are the phospholipids. These have a polar head group and two hydrophobic hydrocarbon tails.
  • What is the cell membrane made up of?

    The Cell Membrane. All living cells and many of the tiny organelles internal to cells are bounded by thin membranes. These membranes are composed primarily of phospholipids and proteins and are typically described as phospholipid bi-layers.
  • What is the lipid bilayer composed of?

    The lipid bilayer is a universal component of all cell membranes. Its role is critical because its structural components provide the barrier that marks the boundaries of a cell. The structure is called a "lipid bilayer" because it is composed of two layers of fat cells organized in two sheets.
  • Why do scientists call the cell membrane a mosaic?

    So scientists actually named this model of the cell the fluid mosaic model, and so the mosaic portion of our cell can be described here. Well, the reason we call the cell membrane fluid is because these pieces in our cell membrane can actually move around. They're not set in stone.
B.

What determines whether or not a molecule can pass through the cell membrane?

Some molecules can diffuse through the cell membrane without any assistance from the cell. Others require the help of transmembrane proteins to move into or out of the cell. Three primary factors determine whether a molecule will diffuse across a cell membrane: concentration, charge and size.
  • Can polar molecules cross the cell membrane?

    The plasma membrane is selectively permeable; hydrophobic molecules and small polar molecules can diffuse through the lipid layer, but ions and large polar molecules cannot. Integral membrane proteins enable ions and large polar molecules to pass through the membrane by passive or active transport.
  • Can salt diffuse across the cell membrane?

    Salt triggers osmosis by attracting the water and causing it to move toward it, across the membrane. Salt is a solute. When you add water to a solute, it diffuses, spreading out the concentration of salt, creating a solution. Cells will not gain or lose water if placed in an isotonic solution.
  • How does soap break up the cell membrane?

    The membranes are made up of two layers of lipids (fat molecules) with proteins going through them. The cell membrane and nucleus can be broken apart by chemical means, such as by the addition of a detergent, which separates the lipid molecules to break down the membrane.

Updated: 6th October 2019

Rate This Answer

3.5 / 5 based on 4 votes.