Plasma membrane

Definition

The plasma membrane is a selectively permeable lipid bilayer that encloses the cytoplasm of a cell, controlling the movement of substances in and out. In prokaryotic cells, it also plays roles in energy generation and cellular processes.

5 Must Know Facts For Your Next Test

1. The plasma membrane is composed primarily of phospholipids and proteins, forming a fluid mosaic model.
2. It regulates the passage of ions, nutrients, and waste materials between the cell and its environment.
3. In prokaryotes, the plasma membrane is involved in processes like respiration and photosynthesis due to lack of organelles.
4. It contains specific receptors for signal transduction, allowing cells to respond to environmental changes.
5. Prokaryotic plasma membranes often have infoldings called mesosomes which may be involved in DNA replication and distribution.

Review Questions

• What are the primary components of the plasma membrane?
• How does the plasma membrane contribute to cellular respiration in prokaryotes?
• What role do mesosomes play in prokaryotic cells?

Related terms

Phospholipid Bilayer: A double layer of phospholipids that forms the core structure of all cell membranes.

Selective Permeability: Property of biological membranes that allows some substances to pass more easily than others.

Signal Transduction: The process by which a cell responds to substances or events outside its environment through signaling pathways.