Summary
The thin, selectively permeable phospholipid boundary that separates the inside of a cell from its surroundings.
In depth
The plasma membrane is a phospholipid bilayer about 7 to 10 nm thick studded with proteins and cholesterol. It acts as a selective gate: small nonpolar molecules (O2, CO2) pass freely, while ions and large polar molecules need protein channels or carriers.
Its functions include transport, signal reception, cell recognition through glycoproteins, anchoring to the cytoskeleton and matrix, and enzymatic activity. Membrane proteins can be integral (spanning the bilayer) or peripheral (attached to one surface).
Frequently asked questions
What is Plasma Membrane?
The thin, selectively permeable phospholipid boundary that separates the inside of a cell from its surroundings.
Which area of biology covers Plasma Membrane, and how advanced is it?
Plasma Membrane is one of the 52 topics in Cell Biology. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Cell Wall, Endocytosis, Nuclear Pore Complex.
Why does Plasma Membrane matter?
The membrane maintains concentration gradients, such as high K+ inside and high Na+ outside, that power nerve impulses and nutrient uptake.
What should I learn before Plasma Membrane?
Plasma Membrane is a Beginner topic, so no earlier topic is required. Other Beginner topics in Cell Biology that pair well with it include Cell Theory, Prokaryotic Cell, Eukaryotic Cell.
What topics are related to Plasma Membrane?
The closest topics to Plasma Membrane are Cell Wall, Endocytosis, Nuclear Pore Complex, Ribosome. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Plasma Membrane?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Plasma Membrane. To practise the whole of Cell Biology, use the Cell Biology quiz.
How is Plasma Membrane different from Cell Wall?
Plasma Membrane: The thin, selectively permeable phospholipid boundary that separates the inside of a cell from its surroundings. Cell Wall: A rigid outer layer outside the plasma membrane in plants, fungi and bacteria that gives shape and protection. Read both side by side and note what each one explains.
How should I study Plasma Membrane step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Cell Wall and explain the difference aloud. Finally, take the Cell Biology quiz and come back to this page for any question you miss.