cell surface

Definition

Target type: cellularcomponent

The external part of the cell wall and/or plasma membrane. [GOC:jl, GOC:mtg_sensu, GOC:sm]

The cell surface is the outermost layer of a cell, separating the internal cellular environment from the external environment. It plays a crucial role in communication, transport, and protection. This complex structure is composed of various components, including:

1. **Plasma membrane:** This is the outermost phospholipid bilayer, which forms a selective barrier, regulating the passage of molecules into and out of the cell. It contains embedded proteins that act as receptors, channels, transporters, and enzymes.

2. **Cell wall:** Present in plant cells, bacteria, fungi, and some protists, the cell wall provides structural support and protection. It is made of cellulose in plants, peptidoglycan in bacteria, chitin in fungi, and silica in diatoms.

3. **Glycocalyx:** This is a carbohydrate-rich layer covering the plasma membrane, composed of glycoproteins and glycolipids. It provides protection, cell-cell recognition, and adhesion, and can act as a barrier against pathogens.

4. **Extracellular matrix (ECM):** Found in animal cells, the ECM is a network of proteins and polysaccharides that surrounds and supports cells. It provides structural support, regulates cell behavior, and facilitates cell-cell interactions. Major components include collagen, elastin, and fibronectin.

5. **Cell junctions:** These specialized structures connect adjacent cells, facilitating communication and tissue integrity. There are three main types:
* **Tight junctions:** Prevent leakage between cells.
* **Desmosomes:** Provide strong cell-cell adhesion.
* **Gap junctions:** Allow direct communication between cells via channels.

6. **Surface appendages:** These structures extend from the cell surface, playing various roles. Examples include:
* **Cilia and flagella:** Hair-like projections involved in movement.
* **Microvilli:** Finger-like projections that increase surface area for absorption.
* **Pili and fimbriae:** Hair-like structures found in bacteria, involved in attachment and conjugation.'
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Proteins (197)

Compounds (5,656)