What molecules can pass through the cell membrane?
Understand the Problem
The question is asking what types of molecules are able to move across the cell membrane, indicating a need to understand the principles of cell membrane permeability and the factors that influence it.
Answer
O2, CO2, H2O, ethanol
Small nonpolar molecules (e.g., O2 and CO2), small uncharged polar molecules (e.g., H2O), and small polar molecules (e.g., ethanol) can pass through the cell membrane.
Answer for screen readers
Small nonpolar molecules (e.g., O2 and CO2), small uncharged polar molecules (e.g., H2O), and small polar molecules (e.g., ethanol) can pass through the cell membrane.
More Information
Small nonpolar molecules can dissolve in the lipid bilayer and diffuse freely. Small uncharged polar molecules can also diffuse, but larger uncharged polar molecules like glucose cannot.
Tips
Avoid assuming any large molecules or charged ions can easily pass through the cell membrane without assistance.
Sources
- Transport of Small Molecules - The Cell - NCBI Bookshelf - ncbi.nlm.nih.gov
- Cell Membranes | Learn Science at Scitable - Nature - nature.com
- 3.1 The Cell Membrane – Anatomy & Physiology - open.oregonstate.education
