What are structures in the cell membrane that allow materials to pass through the membrane?
Key terms
| Term | Meaning |
|---|---|
| Phospholipid | Amphipathic lipid made of glycerol, two fatty acid tails, and a phosphate group |
| Phospholipid bilayer | A biological membrane involving two layers of phospholipids with their tails pointing inward |
| Semipermeable membrane | Membrane that allows certain substances to pass through |
What are the special structures in the cell membrane?
In addition to the phospholipids, the plasma membranes of animal cells contain glycolipids and cholesterol. The glycolipids are found exclusively in the outer leaflet of the plasma membrane, with their carbohydrate portions exposed on the cell surface.
What are three examples of materials that pass through a cell membrane?
Water, carbon dioxide, and oxygen are among the few simple molecules that can cross the cell membrane by diffusion (or a type of diffusion known as osmosis ). Diffusion is one principle method of movement of substances within cells, as well as the method for essential small molecules to cross the cell membrane.
What structure allows small particles to cross membranes?
3 – Simple Diffusion Across the Cell (Plasma) Membrane: The structure of the lipid bilayer allows small, uncharged substances such as oxygen and carbon dioxide, and hydrophobic molecules such as lipids, to pass through the cell membrane, down their concentration gradient, by simple diffusion.
What kinds of molecules pass through a cell membrane most easily?
Small nonpolar molecules, such as O2 and CO2, are soluble in the lipid bilayer and therefore can readily cross cell membranes. Small uncharged polar molecules, such as H2O, also can diffuse through membranes, but larger uncharged polar molecules, such as glucose, cannot.
What kind of materials can move through the cell membrane?
In the case of the cell membrane, only relatively small, nonpolar materials can move through the lipid bilayer (remember, the lipid tails of the membrane are nonpolar). Some examples of these are other lipids, oxygen and carbon dioxide gases, and alcohol.
What causes molecules to pass through the plasma membrane?
Figure 3.1.3 – Simple Diffusion Across the Cell (Plasma) Membrane: The structure of the lipid bilayer allows small, uncharged substances such as oxygen and carbon dioxide, and hydrophobic molecules such as lipids, to pass through the cell membrane, down their concentration gradient, by simple diffusion.
How are proteins involved in the transport of macromolecules?
Proteins embedded within the plasma membrane help to move hydrophilic, polar molecules into the cell. The cytoplasm is the internal medium for cell transport. Vesicle aids in the import and export of macromolecules. Plant cells have a special transport structures that are not found in animal cells, called plasmodesmata.
Which is the internal medium for cell transport?
The cytoplasm is the internal medium for cell transport. Vesicle aids in the import and export of macromolecules. Plant cells have a special transport structures that are not found in animal cells, called plasmodesmata.